ɷ[jack martin] a spectroscopic atlas of bright star

Astronomer’s Pocket Field Guide

For other titles published in this series, go to www.springer.com/series/7814

Jack Martin

A Spectroscopic Atlas of Bright Stars

A Pocket Field Guide

ISBN 978-1-4419-0704-2 e-ISBN 978-1-4419-0705-9DOI 10.1007/978-1-4419-0705-9Springer Dordrecht Heidelberg London New York

Library of Congress Control Number: 2009929021

© Springer Science+Business Media, LLC 2010All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden.The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights.

Printed on acid-free paper

Springer is part of Springer Science+Business Media (www.springer.com)

Jack MartinForest GateLondonUnited Kingdom E7 [email protected]

To my parents, Louis and Polly, who fired my interest in astronomy by buying me my

first telescope when I was 13.

Acknowledgements

I would like to thank Dr. Mike Dworetsky and Stephen Boyle, University of London Observatory, Dr. Robert Lombourne Open University, Professor Emeritus Jim Kaler University of Illinois, Dr. John Fisher, Valerie Desnoux, Christian Buil, Martin Peston, Charles Munton and Ed Palmer for their advice and encouragement in producing this book. And finally thanks to Jim Badura, producer of the Rainbow Optics Star Spectroscope, who said in the owner’s manual, “This seems to be a golden opportunity for amateur spectroscopists to create their own atlas of stellar spectra.” Well, Jim, here it is.

Contents

Dedication .......................................................................................... v

Acknowledgements .......................................................................... vii

Part I

1. Introduction .............................................................................. 3

2. The Greek Alphabet ................................................................. 11

3. The Periodic Table of Elements ............................................. 13

4. The Spectral Sequence ........................................................... 15

Part II

5. The Star Atlas ............................................................................ 25

6. Star Atlas Index ........................................................................ 171

7. Stars By Right Ascension ........................................................ 177

8. Other Examples of Stellar Spectra ....................................... 181

Glossary of Terms ............................................................................. 189

Further Reading ................................................................................. 199

Index .................................................................................................... 201

BookID 149483_ChapID 1_Proof# 1 - 15/09/2009

Part I

Introduction 3


ChaPter 1

IntroduCtIon

astronomical Spectroscopy

Spectroscopy has given us more information about stars than any other branch of astronomy. traditionally the domain of professional astrono-mers, it was an area of astronomy that very few amateurs would get involved in. Complicated texts and mathematics soon puts people off, and they lose interest in a subject that was always thought to be academically and technically difficult. this book demonstrates that this is not the case on a basic understanding level. useful results can be obtained with relatively modest equipment.

one of the purposes of this book is to kick-start an interest in astronomical spectroscopy. there is a need, to make accessible basic information from a theoretical and practical viewpoint for beginners and amateurs that is not available at this level in other books. It is a basic reference book, set out in a practical user-friendly way, that anyone should be able to use without assuming any prior knowledge of the subject. It gives facts and informa-tion about a star that may prove difficult for the reader to find elsewhere and certainly not in one book, as is the case with this publication.

the spectra of stars contain their own unique signatures. this is a useful guide for those who wish to gain a basic insight into the makeup of stars. this atlas has been created from spectra taken on black and white films by an amateur astronomer for amateur astronomers and educational estab-lishments. their use as educational aids should not be underestimated. they are especially useful for GCSe astronomy, a level and undergraduate courses. they can also be used by the amateur for classification and identi-fication purposes.

this atlas is about bright stars that you can see with the naked eye, and relate to, as seen by a naked eye observer (in this case, from light polluted London, england, latitude 51°32′ n, longitude 0°5′ W).

J. Martin, A Spectroscopic Atlas of Bright Stars, Astronomer’s Pocket Field Guide, DOI 10.1007/978-1-4419-0705-9_1, © Springer Science + Business Media, LLC 2010

4 Chapter 1

BookID 149483_ChapID 1_Proof# 1 - 15/09/2009 BookID 149483_ChapID 1_Proof# 1 - 15/09/2009

What’s in this Book?

What you will find in this book is a Greek alphabet, a periodic table of ele-ments; the spectral sequence explained; the star atlas containing 72 labeled spectrograms of bright stars listed in order of the spectral sequence (o B a F G K M), hottest to coolest, showing the elements present, informa-tion about their positions and spectroscopic properties (henry draper number, right ascension coordinate, declination coordinate, magnitude, distance, spectral type, luminosity class, B–V color index, temperature, and radial velocity); a table of spectral lines and wavelengths identified; a draw-ing of the constellation highlighting the star in question; a star atlas index; a table of stars by right ascension; other examples of stellar spectra; a glos-sary; and a further reading section.

equipment

Splitting starlight and imaging the resulting spectrum is not as difficult as one might think. the author’s setup (see Fig. 1.1) consists of a 0.30 m F5.3 newtonian reflector, rainbows optics transmission grating, grating mount, low profile helical focuser, tele-extender (variable focus eyepiece projec-tion tube), t-ring, 35 mm SLr camera body, and a suitable detector, in this case 35 mm black and white film.

there is no slit in the spectroscope, so it only works on pinpoint star-like objects and not on extended objects such as planets. the grating mount is simply a piece of internally threaded aluminum tube that the grating screws into. this, in turn, is housed inside the tele-extender and is locked securely in position by a thumbscrew (see Fig. 1.2). the tele-extender is especially well suited to this type of photography, because it allows the camera/draw tube assembly to be rotated while the grating is in the locked position. the tele-extender is the variable focus type, so when the draw tube is pulled back to enlarge the image, it will go out of focus. the only way to focus the enlarged image is to move the focusing rack mounting plate further forward. But, because of the way a newtonian reflector is designed, there are limits as to how far forward the focusing rack mounting plate can be moved.

Introduction 5


Fig. 1.1 0.30 m F5.3 newtonian reflector (Photo by author.)

6 Chapter 1


It is important to bear in mind that the more the image is enlarged the fainter it becomes. In general, a small but brighter image is better than a large but fainter one. So for this setup, the draw tube focus is always set at the minimum travel image magnification.

the camera body, an olympus oM-1n, is particularly well suited for astro-

photography, because it is a lightweight mechanical camera that does not use a battery, except for the light meter (which is not used for astrophotog-raphy), so the shutter can remain open for as long as necessary. also, the focusing screen is interchangeable. olympus made a 1–8 focusing screen especially for astrophotography.

types of Black and White Film

Color films are not recommended, because the tricolor emulsion has the effect of masking the spectral lines, and the blue end response is poor. When using a digital camera, you will note that the blue end response was also poor compared with black and white films. as a result, very few spec-tral lines were visible in either case.

Fig. 1.2 olympus oM-1n camera bodies and slitless spectroscope assembly

(Photo by author.)

Introduction 7


Where black and white photography is concerned, there are four different film emulsions (see Fig. 1.3):

1. Blue-sensitive to blue, violet, and ultraviolet light

2. orthochromatic-sensitive to blue and green light

3. Panchromatic-sensitive to blue, green and red light, i.e. the entire range of the visible spectrum approximately 400–700 nm

4. extended red panchromatic-sensitive to red and thermal infrared radiation

Panchromatic films such as Kodak tMaX 100–400–3200, Ilford Pan F 50, FP4 125, hP5 400, delta 400–3200, Fuji neopan 400–1600, and Paterson acupan 200–800 were tested. Ilford emulsions are best suited for stellar spectra photography. the six factors that affect the result are:

1. Film speed aSa

2. Spectral sensitivity of the film

Fig. 1.3 Spectral sensitivities of different black and white films (Courtesy of Michael Covington, Astrophotography for the Amateur, reprinted with the permission of Cambridge university Press, 2001.)

8 Chapter 1


3. Color of the star

4. Magnitude

5. Phase of the Moon.

6. aperture of the telescope primary mirror/lens.

the general rule of thumb is to use slow films for bright stars and fast films for fainter stars. the spectral sensitivity of different panchromatic films can vary. In the spectrograms of Mizar a + B (see Fig. 1.4), taken on Fuji neopan 1600 and Ilford delta 3200 films, the latter has an extended red sensitivity and shows the ha line 656.3 nm.

Film manufacturers’ technical data usually contains a spectral sensitivity curve (see Fig. 1.5), which shows sensitivity against wavelength (nm). the cooler stars do not photograph as well as the hotter stars, because the panchromatic film is less sensitive to the star’s color, an all important fac-tor, which is ultimately determined by the star’s temperature.

Photographing stellar spectra is best done in the absence of moonlight, so sunrise and sunset tables are needed and should be used to determine when astronomical twilight begins and ends, before starting an observing session.

Fig. 1.4 the spectra of Mizar a and B taken on Fuji neopan 1600 and Ilford delta 3200 black and white films (Spectrograms by author.)

Introduction 9


Method of Photography

the star’s spectrum is recorded using the motion of earth (diurnal motion), by allowing the star and its first-order spectrum to drift across the field of view, parallel to the long edge of the camera viewfinder, until the spec-trum is widened sufficiently enough to show the detail of the spectral lines. Since all stars from London appear to revolve around Polaris, the pole star, the drift time can vary from 15 s to 2 min to produce a satisfac-tory spectrogram.

developing and Printing of Film

all developing and printing is done by this author in a darkroom. Black and white photographic paper size 12.7 × 17.8 cm is used. the process is the same for all black and white films. the only variant is the develop-ment time. the width of the spectral image on the negative varies, depending on the spectral sensitivity of the film. the image is then enlarged to the same magnification as the spectral lines of a guide print of a star of the same spectral type, as seen when superimposed on the negative image.

Fig. 1.5 Spectral sensitivity of Ilford delta 3200 black and white film (reprinted with the permission of llford/harman films.)

10 Chapter 1


digitizing Black and White Prints

the print is scanned at the lowest resolution and saved as a bitmap image. the image is loaded into Christian Buil’s IrIS program and saved as a FItS (Flexible Image transport System) image. the FItS image is then loaded into Valerie desnoux’s Visual Specs program, which converts the image to the spectral profile of the star, showing a wavelength scale in angstrom units on the x-axis and an arbitrary brightness scale on the y-axis, these were not calibrated as photometric uni. the more modern nanometer unit is used in the table of spectral lines and wavelengths identified, which are rest wavelengths (see glossary for definition) as opposed to measured ones. the FItS image and the spectral profile is exported to a Microsoft Word document. the profile is then stacked on top of the spectrogram to give the final result, the spectrum of the star and its profile (see Fig. 1.6).

Fig. 1.6 the spectrum and profile of a CMa Sirius (Spectrogram by author.)

The Greek Alphabet 11


Chapter 2

the Greek alphabet

alpha abeta bGamma gDelta depsilon eZeta zeta htheta qIota ikappa klambda lMu mNu nXi xOmicron opi prho rSigma stau tUpsilon uphi fChi cpsi yOmega w


The Periodic Table of Elements 13


Chapter 3

the periodiC table of elements


atomic number element symbol


1 hydrogen h 53 iodine i 2 helium he 54 Xenon Xe 3 lithium li 55 Cesium Cs 4 beryllium be 56 barium ba 5 boron b 57 lanthanum la 6 Carbon C 58 Cerium Ce 7 nitrogen n 59 praseodymium pr 8 oxygen o 60 neodymium nd 9 fluorine f 61 promethium pm10 neon ne 62 samarium sm11 sodium na 63 europium eu12 magnesium mg 64 Gadolinium Gd13 aluminum al 65 terbium tb14 silicon si 66 dysprosium dy15 phosphorus p 67 holmium ho16 sulfur s 68 erbium er17 Chlorine Cl 69 thulium tm18 argon ar 70 Ytterbium Yb19 potassium K 71 lutecium lu20 Calcium Ca 72 hafnium hf21 scandium sc 73 tantalum ta22 titanium ti 74 tungsten W23 Vanadium Va 75 rhenium re24 Chromium Cr 76 osmium os25 manganese mn 77 iridium ir26 iron fe 78 platinum pt27 Cobalt Co 79 Gold au28 nickel ni 80 mercury hg

(continued)

14 Chapter 3




29 Copper Cu 81 thallium tl30 Zinc Zn 82 lead pb31 Gallium Ga 83 bismuth bi32 Germanium Ge 84 polonium po33 arsenic as 85 astatine at34 selenium se 86 radon rn35 bromine br 87 francium fr36 Krypton Kr 88 radium ra37 rubidium rb 89 actinium ac38 strontium sr 90 thorium th39 Yttrium Y 91 protoactinium pa40 Zirconium Zr 92 Uranium U41 niobium nb 93 neptunium np42 molybdenum mo 94 plutonium pu43 technetium tc 95 americium am44 ruthenium ru 96 Curium Cm45 rhodium rh 97 berkelium bk46 palladium pd 98 Californium Cf47 silver ag 99 einsteinium es48 Cadmium Cd 100 fermium fm49 indium in 101 mendelevium md50 tin sn 102 nobelium no51 antimony sb 103 lawrencium lr52 tellurium te

(continued)

The Spectral Sequence 15


Chapter 4

the SpeCtral SequenCe

the Spectral sequence is a surface temperature sequence pioneered by Father angelo Secchi in 1866 and developed at harvard in the 1890’s by eC pickering, Williamina Fleming antonia Maury and annie Cannon resulting in the famous seven letter sequence OBaFGKM. the harvard-Drape system was further improved at the Yerkes Observatory in 1943 by William Morgan, phillip Keenan and edith Kellman, known as the MKK system in which the spectral characteristics are related to the luminosity of the star concerned.

Spectral Class Characteristics

Spectral class principal characteristics temperature (K)

O hot blue stars relatively few lines hydrogen Balmer hI lines weak ionized helium heII lines dominate

28,000–50,000

B Blue white stars hydrogen Balmer hI lines stronger neutral helium heI lines dominate

9,900–28,000

a White stars ionized Calcium CaII lines strengthening hydrogen Balmer hI lines dominate

7,400–9,900

F Whitish stars neutral metals Iron FeI and Chromium CrI lines and ionized Calcium CaII lines strengthening

6,000–7,400

G Yellow stars many neutral metals Iron FeI Manganese MnI lines ionized Calcium CaII lines dominate

4,900–6,000

J. Martin, A Spectroscopic Atlas of Bright Stars, Astronomer’s Pocket Field Gride, DOI 10.1007/978-1-4417-1346-9_4, © Springer Science + Business Media, LLC 2010

(continued)

16 Chapter 4


Spectral class principal characteristics temperature (K)

K Orange red stars molecular bands appear neutral metal Iron FeI lines and titanium Oxide tiO2 bands dominate

3,600–4,900

M Cool red stars neutral metal Magnesium MgI lines strong titanium Oxide tiO2 bands dominate

2,000–3,600

readers please note C-r, C-n, S, l, t, Y type stars are mentioned in the glossary see /Spectral type/ p 196.

Fig. 4.1 Spectral absorption features (reprinted by permission of harperCollins publishers limited. Collins Dictionary of astronomy © 1994 Collins (edited by Valerie Illingworth).

(continued)



Fig.

4.2

ele

men

ts i

n t

he

Sun

(C

ourt

esy

of J

ames

B.

Kal

er,

The

Cam

brid

ge E

ncyc

lope

dia

of

Star

s, r

epri

nte

d w

ith

th

e p

erm

issi

on o

f Cam

bri

dg

e u

niv

ersi

ty p

ress

, 200

6.)

18 Chapter 4


d Ori Mintaka Spectral type 09.5 luminosity Class II temperature 30,000 K Magnitude 2.23. Contains singly ionized helium (heII) lines. hydrogen Balmer (h) lines appear only weakly.

g Ori Bellatrix Spectral type B2 luminosity Class III temperature 21,500 K Magnitude 1.64. neutral helium (heI) lines dominate. hydrogen Balmer (h) lines become stronger.



a CMi procyon Spectral type F5 luminosity Class IV–V temperature 6,530 K Magnitude 0.38. the h and K lines of ionized Calcium (CaII) and other metal lines strengthen.

a lyr Vega Spectral type a0 luminosity Class V temperature 9,500 K Magnitude 0.03. hydrogen Balmer (h) lines dominate and merge into a continuum.

20 Chapter 4


a aur Capella Spectral type G8 luminosity Class III temperature 5,300 K Magnitude 0.08. the h and K lines of ionized Calcium (CaII) are strong. neutral metal lines Iron (FeI) Magnesium (MgI) and Calcium (CaI) are strengthening.

b Gem pollux Spectral type K0 luminosity Class III temperature 4,770 K Magnitude 1.14. the hydrogen lines are almost gone. the h and K lines of ion-ized Calcium (CaII) are strong other neutral metal lines Magnesium (MgI) and Iron (FeI) are very prominent.



a Ori Betelgeuse Spectral type M2 luminosity Class I temperature 3,600 K Magnitude 0.50. the neutral metal lines Magnesium (MgI) are strong. Molecular bands are prominent with broad titanium Oxide (tiO) bands dominating.


Part II

The Star Atlas 25


ChaPter 5

the Star atlaS


26 Chapter 5


The Star Atlas 27


B-V

K

h2.

77II

I

28 Chapter 5


The Star Atlas 29


B-V

K-1

hm

30 Chapter 5


The Star Atlas 31


B-V

K−1

hm

915

II

32 Chapter 5


The Star Atlas 33


B-V

K-1

hm

447.

1

34 Chapter 5


The Star Atlas 35


B-V

K-1

h

36 Chapter 5


The Star Atlas 37


B-V

K−1

5394

56

656.

3

38 Chapter 5


The Star Atlas 39


B-V

K

4474

3h

m33

.7

2

40 Chapter 5


The Star Atlas 41


B-V

K

hm

s

x

42 Chapter 5


The Star Atlas 43


lyK

hm

44 Chapter 5


The Star Atlas 45


B-V

K

hm

393.

4

χ

46 Chapter 5


The Star Atlas 47


B-V

K

hm

333

IV

48 Chapter 5


The Star Atlas 49


B-V

K

h3.

66

50 Chapter 5


The Star Atlas 51


B-V

K

hm

B3

V

52 Chapter 5


The Star Atlas 53


B-V

K

hm

B3

III

434 .5

54 Chapter 5


The Star Atlas 55


lyB

-VK

hm

B6

III

56 Chapter 5


The Star Atlas 57


B-V

K

B7

III

58 Chapter 5


a L

eo R

egul

us

The Star Atlas 59


B-V

K

hm

77B

7V

h

60 Chapter 5


The Star Atlas 61


B-V

K

hV

o

62 Chapter 5


41 A

ri 4

1 A

riet

is

The Star Atlas 63


K

hm

s3.

63

a

64 Chapter 5


The Star Atlas 65


B-V

K

hV

e

66 Chapter 5


The Star Atlas 67


B-V

K−1

14m

775

68 Chapter 5


The Star Atlas 69


B-V

K

m

70 Chapter 5


The Star Atlas 71


DE

CB

-VK

9500

B9

V

α

72 Chapter 5


The Star Atlas 73


B-V

K

hm

III

74 Chapter 5


The Star Atlas 75


lyB

-VK

m

76 Chapter 5


The Star Atlas 77


K

h m

75V

78 Chapter 5


The Star Atlas 79


B-V

K

m3.

3

80 Chapter 5


The Star Atlas 81


B-V

K

hIV

θ

82 Chapter 5


The Star Atlas 83


B-V

K

hm

e

84 Chapter 5


The Star Atlas 85


B-V

K

hm

B3

V

86 Chapter 5


The Star Atlas 87


K

36m

656.

31

88 Chapter 5


The Star Atlas 89


B-V

K

m

90 Chapter 5


The Star Atlas 91


K

37

z

92 Chapter 5


The Star Atlas 93


ly

B-V

Kh

mV

–7.6

656.

3

94 Chapter 5


a G

em

Cas

tor

The Star Atlas 95


lyB

-VK

h

656.

3

x

96 Chapter 5


The Star Atlas 97


B-V

K

hV

nn

98 Chapter 5


The Star Atlas 99


B-V

K

hm

V

100 Chapter 5


The Star Atlas 101


RA

DE

CK

m m2.

273.

95A

2A

1V m

-5.6

102 Chapter 5


a C

yg D

eneb

The Star Atlas 103


B-V

K

hm

-4.5

104 Chapter 5


The Star Atlas 105


B-V

K

m3.

34V

7.6

106 Chapter 5


The Star Atlas 107


B-V

K

h

108 Chapter 5


The Star Atlas 109


B-V

K

hm

V

110 Chapter 5


The Star Atlas 111


B-V

K

m

656.

3

112 Chapter 5


The Star Atlas 113


lyB

-VK

hm

36V

114 Chapter 5


The Star Atlas 115


B-V

K

hV

116 Chapter 5


The Star Atlas 117


lyB

-VK

h m

6.7

118 Chapter 5


The Star Atlas 119


lyB

-VK

mV

�

120 Chapter 5


The Star Atlas 121


B-V

K

hm

122 Chapter 5


The Star Atlas 123


B-V

K–1

13h

mV

124 Chapter 5


� Cep

A

lder

amin

H�

H�

H�

H�

CaI

I

H8

H9

H10

H11

The Star Atlas 125


B-V

K

h

126 Chapter 5


The Star Atlas 127


K

hm

0304

;

128 Chapter 5


The Star Atlas 129


Mag

B-V

K-1

m3.

44-1

5.6

130 Chapter 5


The Star Atlas 131


B-V

K−1

3667

3h

m

h

132 Chapter 5


The Star Atlas 133


K

m50

134 Chapter 5


The Star Atlas 135


B-V

K

hm

F5−3

.2

136 Chapter 5


The Star Atlas 137


B-V

z

K-1

hm

F5

431.

4

138 Chapter 5


The Star Atlas 139


B-V

K−1

0011

2h

m3.

4165

F6

431.

4

140 Chapter 5


γ C

yg

Sad

r

Hβ

CaI

I/H

ε

CaI

I

H8

H9

Hγ

G

FeI

The Star Atlas 141


Pro

pert

ies

HD

R

A

2000

D

EC

20

00

Mag

Dista

ncel

y Sp

ectr

al

Typ

e Lum

inos

ity

Cla

ss

B-V

C

olor

In

dex

Tem

pera

ture

K

R

adia

l V

eloc

ity

km

s–1

1940

9320

h 22m

13.6

s+40

° 15

´ 24

˝2.

2015

00F

8Ia

b0.

6665

00–7

.5

Spec

tral

lin

eW

avel

engt

h/nm

Hβ

Hγ

Hε

δ

ϕ

β

η

γ C

yg S

adr

θχ

α

ζ

εH

9

486.

143

4.0

G43

1.4

FeI

417.

139

7.0

CaI

I39

6.8

CaI

I39

3.4

H8

388.

938

3.5

Spec

tral

lin

es ide

ntifie

d

Cyg

nus

142 Chapter 5


The Star Atlas 143


tyB

-VK

−1

4614

m3.

44p

431.

4

144 Chapter 5


The Star Atlas 145


B-V

K-1

43m

438.

3

431.

4

396.

839

3.4

146 Chapter 5


The Star Atlas 147


B-V

K-1

hm

518.

451

7.3

516.

748

6.1

431.

4

383.

5

148 Chapter 5


The Star Atlas 149


B-V

K

hm

393.

4

c

150 Chapter 5


The Star Atlas 151


K-1

hm

3.48

117

G8

438.

3

396.

839

3.4

152 Chapter 5


The Star Atlas 153


#$%

K−1

h1.

1434

518.

451

7.3

516.

7

438.

343

1.4

396.

839

3.4

x

154 Chapter 5


The Star Atlas 155


B-V

K−1

1979

89m

438.

343

1.4

396.

839

3.4

ϕ

156 Chapter 5


The Star Atlas 157


B-V

K-1

#1.

18-3

.8

438.

343

1.4

396.

839

3.4

158 Chapter 5


The Star Atlas 159


B-V

K-1

9568

911

h m

1.49

-8.9

438.

343

1.4

396.

839

3.4

160 Chapter 5


The Star Atlas 161


B-V

K-1

h66

1.15

431.

4

396.

839

3.4

b

162 Chapter 5


The Star Atlas 163


$%&

K-1

hm

K5

1.54

54.3

518.

451

7.3

516.

7

438.

3

68

164 Chapter 5


The Star Atlas 165


B-V

K

m

166 Chapter 5


The Star Atlas 167


B-V

K-1

m1.

677.

9

518.

451

7.3

516.

7

168 Chapter 5


The Star Atlas 169


K−1

hm

1.77

518.

451

7.3

516.

749

9.5

Star Atlas Index 171


Chapter 6

Star atlaS Index

J. Martin, A Spectroscopic Atlas of Bright Stars, Astronomer’s Pocket Field Gude, DOI 10.1007/978-1-4417-1346-9_6, © Springer Science + Business Media, LLC 2010

172 Chapter 6


Spec

tral

typ

eB

ayer

nam

epr

oper

nam

eC

onst

ella

tion

ab

bre

viat

ion

latin

gen

itive

O9

i Ori

nai

r al S

aif

Orio

nO

riO

rioni

sO

9.5

z Ori

alni

tak

Orio

nO

riO

rioni

sO

9.5

d Ori

Min

taka

Orio

nO

riO

rioni

sB0

k O

riSa

iph

Orio

nO

riO

rioni

sB0

e Ori

alni

lam

Orio

nO

riO

rioni

sB0

g Cas

Cih

Cass

iope

iaCa

sCa

ssio

peia

eB1

b CM

aM

irzam

Cani

s M

ajor

CMa

Cani

s M

ajor

isB1

z per

pers

eus

per

pers

eiB1

a Vi

rSp

ica

Virg

oVi

rVi

rgin

isB2

g Ori

Bella

trix

Orio

nO

riO

rioni

sB2

g peg

alge

nib

pega

sus

peg

pega

siB2

z Cas

Cass

iope

iaCa

sCa

ssio

peia

eB3

h U

Ma

alka

idU

rsa

Maj

orU

Ma

Urs

ae M

ajor

isB3

e Cas

Segi

nCa

ssio

peia

Cas

Cass

iope

iae

B6z d

ran

odus

1d

raco

dra

dra

coni

sB7

b tau

el n

ath

taur

usta

uta

uri

B7a

leo

regu

lus

leo

leo

leon

isB8

b pe

ral

gol

pers

eus

per

pers

eiB8

41 a

ri41

arie

tisar

ies

ari

arie

tisB8

b CM

iG

omei

saCa

nis

Min

orCM

iCa

nis

Min

oris



B8b

Ori

rige

lO

rion

Ori

Orio

nis

B8a

and

alph

erat

zan

drom

eda

and

andr

omed

aeB9

a pe

gM

arka

bpe

gasu

spe

gpe

gasi

B9/a

0g 1

+ 2

ari

Mes

arth

imar

ies

ari

arie

tisB9

.5d

Cyg

Cygn

usCy

gCy

gni

a0q a

urau

riga

aur

aurig

aea0

a Cr

Bal

phec

caCo

rona

Bor

ealis

CrB

Coro

nae

Bore

alis

a0h

leo

al Ja

bhah

leo

leo

leon

isa0

z aql

den

eb e

l Oka

baq

uila

aql

aqui

lae

a0g U

Ma

phec

daU

rsa

Maj

orU

Ma

Urs

ae M

ajor

isa0

a ly

rVe

galy

raly

rly

rae

a0e U

Ma

alio

thU

rsa

Maj

orU

Ma

Urs

ae M

ajor

isa0

g Gem

alhe

naG

emin

iG

emG

emin

orum

a1a

CMa

Siriu

sCa

nis

Maj

orCM

aCa

nis

Maj

oris

a1a

Gem

Cast

orG

emin

iG

emG

emin

orum

a1g t

ritr

iang

ulum

tri

tria

ngul

ia1

b U

Ma

Mer

akU

rsa

Maj

orU

Ma

Urs

ae M

ajor

isa2

/a1

z UM

aM

izar

a +

BU

rsa

Maj

orU

Ma

Urs

ae M

ajor

is

(con

tin

ued

)

174 Chapter 6


Spec

tral

type

Baye

r nam

epr

oper

nam

eCo

nste

llatio

nab

brev

iatio

nla

tin g

eniti

ve

a2a

Cyg

den

ebCy

gnus

Cyg

Cygn

ia2

q leo

Chor

tle

ole

ole

onis

a2b

aur

Men

kalin

anau

riga

aur

aurig

aea3

d UM

aM

egre

zU

rsa

Maj

orU

Ma

Urs

ae M

ajor

isa3

g UM

iph

erka

dU

rsa

Min

orU

Mi

Urs

ae M

inor

isa3

b le

od

eneb

ola

leo

leo

leon

isa4

d leo

Zosm

ale

ole

ole

onis

a5d C

asru

chba

hCa

ssio

peia

Cas

Cass

iope

iae

a5b

ari

Sher

atan

arie

sar

iar

ietis

a5b t

rid

elto

tron

tria

ngul

umtr

itr

iang

uli

a580

UM

aal

cor

Urs

a M

ajor

UM

aU

rsae

Maj

oris

a7a

Cep

alde

ram

inCe

phus

Cep

Ceph

eia7

a aq

lal

tair

aqui

laaq

uaq

uila

eF0

z leo

aldh

afer

ale

ole

ole

onis

F0a

lep

arne

ble

pus

lep

lepo

risF2

b Ca

sCa

phCa

ssio

peia

Cas

Cass

iope

iae

F5a

CMi

proc

yon

Gem

ini

Gem

Gem

inor

umF5

a pe

rM

irfak

pers

eus

per

pers

ei

(con

tin

ued

)



F6a

tri

Mot

halla

htr

iang

ulum

tri

tria

ngul

iF8

g Cyg

Sadr

Cygn

usCy

gCy

gni

G0

h Ca

sac

hird

Cass

iope

iaCa

sCa

ssio

peia

eG

2h

peg

Mar

tar

pega

sus

peg

pega

siG

8a

aur

Cape

llaau

riga

aur

aurig

aeG

8z C

ygCy

gnus

Cyg

Cygn

iG

8m

peg

Sad

al B

ari

pega

sus

peg

pega

siK0

b G

empo

llux

Gem

ini

Gem

Gem

inor

umK0

e Cyg

Gie

nah

Cygn

usCy

gCy

gni

K0a

Cas

Shed

arCa

ssio

peia

Cas

Cass

iope

iae

K0a

UM

ad

ubhe

Urs

a M

ajor

UM

aU

rsae

Maj

oris

K2a

ari

ham

alar

ies

ari

arie

tisK5

a ta

ual

deba

ran

taur

usta

uta

uri

M0

b an

dM

irach

andr

omed

aan

dan

drom

edae

M2

b pe

gSh

eat

pega

sus

peg

pega

siM

2a

Ori

Bete

lgeu

seO

rion

Ori

Orio

nis

Stars by Right Ascension 177


Chapter 7

StarS by right aSCenSion


bayer name proper name ra 2000 DeC 2000

a and alpheratz 00 h 08 min 23.2s +29°05¢26b Cas Caph 00 h 09 min 10.6s +59°08¢59”g peg algenib 00 h 13 min 14.1s +15°11¢01”z Cas 00 h 36 min 58.2s +53°53¢49”a Cas Shedar 00 h 40 min 30.4s +56°32¢15”h Cas archird 00 h 49 min 06.0s +57°48¢58”g Cas Cih 00 h 56 min 42.4s +60°43¢00”b and Mirach 01 h 09 min 43.9s +35°37¢14”d Cas ruchbah 01 h 25 min 48.9s +60°14¢07”a tri Mothallah 01 h 53 min 04.8s +29°34¢44”g1 ari Mesarthim 01 h 53 min 31.7s +19°17¢45”g2 ari Mesarthim 01 h 53 min 31.8s +19°17¢37”e Cas Segin 01 h 54 min 23.6s +63°40¢13”b ari Sheratan 01 h 54 min 38.3s +20°48¢29”a ari hamal 02 h 07 min 10.3s +23°27¢45”b tri Deltotron 02 h 09 min 32.5s +34°59¢14”g tri 02 h 17 min 18.8s +33°50¢50”41 ari 41 arietis 02 h 49 min 59.0s +27°15¢38”b per algol 03 h 08 min 10.1s +40°57¢21”a per Mirfak 03 h 24 min 19.3s +49°51¢41”z per 03 h 54 min 07.9s +31°53¢01”a tau aldebaran 04 h 35 min 55.2s +16°30¢33”b ori rigel 05 h 14 min 32.2s −08°12¢06”a aur Capella 05 h 16 min 41.3s +45°59¢53”g ori bellatrix 05 h 25 min 07.8s +06°20¢59”b tau el nath 05 h 26 min 17.5s +28°36¢27”d ori Mintaka 05 h 32 min 00.3s −00°17¢57”a Lep arneb 05 h 32 min 43.7s −17°49¢20”i ori nair al Saif 05 h 35 min 25.9s −05°54¢36”

(continued)

178 Chapter 7



e ori alnilam 05 h 36 min 12.7s −01°12¢07”z ori alnitak 05 h 40 min 45.5s −01°56¢34”k ori Saiph 05 h 47 min 45.3s −09°40¢11”a ori betelgeuse 05 h 55 min 10.3s +07°24¢25”b aur Menkalinan 05 h 59 min 31.7s +44°56¢51”q aur 05 h 59 min 43.2s +37°12¢45”b CMa Mirzam 06 h 22 min 41.9s −17°57¢22”g gem alhena 06 h 37 min 42.7s +16°23¢57”a CMa Sirius 06 h 45 min 08.9s −16°42¢58”b CMi gomeisa 07 h 27 min 09.0’s +08°17¢21”a gem Castor 07 h 34 min 35.9s +31°53¢18”a CMi procyon 07 h 39 min 18.1s +05°13¢30”b gem pollux 07 h 45 min 18.9s +28°01¢34”h Leo al Jabhah 10 h 07 min 19.9s +16°45¢45”a Leo regulus 10 h 08 min 22.2s +11°58¢02”z Leo aldhafera 10 h 16 min 41.4s +23°25¢02”b UMa Merak 11 h 01 min 50.4s +56°22¢56”a UMa Dubhe 11 h 03 min 43.6s +61°45¢03”d Leo Zosma 11 h 14 min 06.4s +20°31¢25”q Leo Chort 11 h 14 min 14.3s +15°25¢46”b Leo Denebola 11 h 49 min 03.5s +14°34¢19”g UMa phecda 11 h 53 min 49.8s +53°41¢41”d UMa Megrez 12 h 15 min 25.5s +57°01¢57”e UMa alioth 12 h 54 min 01.7s +55°57¢35”z a UMa Mizar a 13 h 23 min 55.5s +54°55¢31”z b UMa Mizar b 13 h 23 min 56.3s +54°55¢18”a Vir Spica 13 h 25 min 11.5s −11°09¢41”80 UMa alcor 13 h 25 min 13.4s +54°59¢17”h UMa alkaid 13 h 47 min 32.3s +49°18¢48”a boo arcturus 14 h 15 min 39.6s +19°10¢57”g UMi pherkad 15 h 20 min 43.6s +71°50¢02”a Crb alphecca 15 h 34 min 41.2s +26°42¢53”z Dra nodus 1 17 h 08 min 47.1s +65°42¢53”a Lyr Vega 18 h 36 min 56.2s +38°47¢01”z aql Deneb el okab 19 h 05 min 24.5s +13°51¢48”d Cyg 19 h 44 min 58.4s +45°07¢51”

(continued)

(continued)

Stars by Right Ascension 179



a aql altair 19 h 50 min 46.9s +08°52¢06”g Cyg Sadr 20 h 22 min 13.6s +40°15¢24”a Cyg Deneb 20 h 41 min 25.8s +45°16¢49”e Cyg gienah 20 h 46 min 12.6s +33°58¢13”z Cyg 21 h 12 min 56.1s +30°13¢37”a Cep alderamin 21 h 18 min 34.7s +62°35¢08”h peg Martar 22 h 43 min 00.1s +30°13¢17”m peg Sad al bari 22 h 50 min 00.1s +24°36¢06”b peg Scheat 23 h 03 min 46.4s +28°04¢58”a peg Markab 23 h 04 min 45.6s +15°12¢19”

(continued)

Other Examples of Stellar Spectra 181


Chapter 8

Other examples Of stellar speCtra

J. Martin, A Spectroscopic Atlas of Bright Stars, Astromer’s Pocket Field Guide, DOI 10.1007/978-1-4419-0705-9_8, © Springer Science + Business Media, LLC 2010

Fig. 8.2 aries. 41 arietis hamal sheratan mesarthim. spectrograms by author.

Fig. 8.1 spectrum and properties of arcturus. spectrogram by author.

a Boo Arcturus

Properties

HD RA DEC Mag Distancely

SpectralType

LuminosityClass

B-VColourIndex

TemperatureK

RadialVelocitykm s–1

124897 14h 15m 39.6s +19° 10´ 57˝ –0.04 37 K2 III 1.15 4290 –5.2

G

CaI

CaIICaIIHβ

182 Chapter 8


Fig. 8.3 spectra of stars from B6 to a4 showing the appearance and increase in strength of the K line at 3934Å as the temperature decreases. spectrograms by author.

Fig. 8.4 Double stars mizar a+B and mesarthim. the spectrum of each star is blended into the spectrogram. Both components of each double star system are visible. spectrograms by author.



Fig. 8.5 pleiades 1. spectrogram by author.

184 Chapter 8


Fig. 8.6 pleiades 2. spectrogram by author.



Fig. 8.7 the summer triangle Vega Deneb altair. spectrograms by author.

Fig. 8.8 the Winter triangle. Betelgeuse procyon sirius. spectrograms by author.

186 Chapter 8


Fig. 8.9 triangulum. mothallah Deltotron Gamma trianguli. spectrograms by author.



Fig. 8.10 the square of pegasus. algenib alpheratz markab scheat. spectrograms by author.

188 Chapter 8

Core temperature 15,000,000 KPhotosphere 5780 KChromosphere 6,000-20,000 KCorona 2,000,000 KSpectral type G2Luminosity class VLuminosity 3.85 x 1026 Js−1

Mean distance 1.495 x 1011 mRotation period 26.8 days

MgIMgIMgI

FeI/FeII

Lhires 3 Spectrograph2400g/mm grating25mm Zeiss eyepieceCanon EOS 400D

Hydrogen Alpha

656.3

Hα

Sodium Doublet589.0 589.6

Magnesium Triplet

NaI NiI NaI

516.7 517.3 518.4

Fig. 8.11 Some prominent Spectral lines in the Sun.

Glossary of Terms 189

BookID 149483_ChapID BM_Proof# 1 - 15/09/2009

Glossary of Terms

Absorption line: a dark line formed at a particular wavelength when an electron jumps from a lower to a higher energy level in an atom while absorbing light from a bright, continuous background source.

Angstrom Å: a unit of length equal to 10−10 m, or 10−8 cm, or 0.1nm.

Atomic spectra: Transitions between atomic energy levels within atoms that lead to the absorption or emission of radiation in a series of sharply defined lines, corresponding to fixed wavelengths representing radiation quanta of definite energies. There are six named series of lines for hydrogen:

lyman far ultravioletBalmer series seen at visible wavelengthsPaschen infraredBrackett far infraredPfund far infraredHumphreys far infrared

Be-type stars: B-type stars with bright emission lines of hydrogen, which are superimposed on the normal dark absorption lines, e.g., Gamma Cassiopeiae.

Blackbody radiation: The emission of radiation from incandescent mate-rial independent of the chemical composition and physical nature of the material. a black body is both a perfect absorber and emitter of radiation. any radiation is absorbed without loss due to reflection or transmission.

Blaze angle: In a grating the faces of the grooves are cut at a constant angle to the plane of the original surface of the grating material. The angle of inclination of the grooves is known as the blaze angle. Blazing concen-trates the diffracted spectrum in a specific order and wavelength range.

B–V color index: The color or measure of a star’s color. B–V may need to be corrected for interstellar reddening before an accurate temperature value can be estimated. estimation is done by observing the star’s magnitude through two different filters from the UBVrI Johnson–Cousins filters sys-tem, where U is sensitive to ultraviolet light, B is sensitive to blue light, V is

190 Glossary of Terms

BookID 149483_ChapID BM_Proof# 1 - 15/09/2009 BookID 149483_ChapID BM_Proof# 1 - 15/09/2009

sensitive to green-yellow light, r is sensitive to red light, and I is sensitive to infrared light. The difference in magnitude found is the B–V color index. The more negative the color index, the bluer (the hotter) the object is, e.g., rigel is −0.03. (Its B magnitude is 0.09 and its V magnitude is 0.12; so B–V = −0.03.) The more positive the color index, the redder (the cooler) the object is, e.g., the sun +0.66.

Chromosphere: a region of the sun’s atmosphere lying above the photo-sphere with a temperature of 6,000–20,000K.

Color magnitude diagram: a graph showing significant correlations between a star’s color and its luminosity. Color is related to effective tem-perature and spectral class. see HR diagram.

Continuous spectrum: Incandescent solids emit a spectrum consisting of all wavelengths in a given range (a continuous spectrum), without any absorption or emission lines.

Continuum: Part of the spectrum that has neither absorption or emission lines with only a smooth wavelength distribution.

Corona: The outermost region of the sun’s atmosphere with a temperature of around 2,000,000K.

Declination (DEC d): a coordinate used with right ascension in the equato-rial coordinate system analogous to latitude, expressed in degrees (°), minutes (¢) and seconds (″) of arc. objects north of the celestial equator have + declinations, and those south have − declinations. objects on the celestial equator have a declination of 0°, and the poles ±90°.

Diffraction: This occurs when a wavefront passes through narrow slits and at sharp edges. It is due to the wave nature of light.

Diffraction grating: Invented by american astronomer David rittenhouse in 1785. The conventional grating consists of a series of closely spaced parallel lines scored onto the surface of a metal or glass. spectra are pro-duced by diffraction of the wavefront at the grating surface. The dispersion of spectral lines through a grating is linear, whereas through a prism it is nonlinear.



Dispersion: The ability of a grating or prism to separate the visible wave-lengths of radiant energy into a spectrum measured in Å/mm or nm/mm.

Doppler broadening: The broadening of absorption or emission lines by the thermal motion of atoms.

Doppler effect: a change of frequency of electromagnetic radiation due to relative motion between the observer and the source along the observer’s line of sight.

Doppler shift: The change in wavelength observed when a body emitting light is moving away from (red shifted) or toward (blue shifted) along the observer’s line of sight.

Echelette/Echelle gratings: a very accurately ruled reflection grating with about 1,000 lines cm−1 and a broad groove such that about 75% of the reflected light is concentrated in one order.

an echelle grating is a coarse form of echelette grating with fewer fine lines that are more widely spaced. This arrangement gives a higher resolution over a narrower waveband such that 50 lines cm−1 can give a resolving power comparable to 10,000 lines cm−1.

Electromagnetic radiation: radiation that carries energy through space in a vacuum at the speed of light.

Electromagnetic spectrum: Considered to consist of the region of radiant energy ranging from wavelengths of 1 × 10−10 cm to 10m, that is gamma rays–xrays–ultraviolet–visible–infrared and radio waves.

Electron: The Greek word for amber, also called a negatron, a negatively charged elementary particle theorized by G. Johnstone stoney in 1874 and discovered by J.J. Thomson in 1897:

mass = 9.109,534 × 10−31 kgCharge = 1.602,189 × 10−19 Cspin quantum number = 1/2

Electron volt: The eV is a unit of energy equal to the energy gained by an electron when it accelerates through a potential difference of 1 V in a vac-uum equal to 1.602 × 10−19 joules.



Emission line: a bright line formed at a particular wavelength when an electron jumps from a higher to a lower energy level in an atom by emit-ting a photon of a specific wavelength. see Be-type stars.

Energy level: a quantity of energy associated with a bound electron orbit-ing around an atomic nucleus. an increase in energy will shift the electron to a higher energy level within an atom.

Excitation: an atomic process where an atom or ion is raised to a higher energy state by an electron jumping from a lower to a higher energy level.

Flash Spectrum: an emission line spectrum of the solar chromosphere seen just before and after totality of an eclipse of the sun.

Forbidden lines: lines not found in spectra under normal terrestial condi-tions, but are observed in certain astronomical spectra such as emission nebulae, because under normal laboratory conditions such atoms would be deexicited by collisions with other atoms before they had time to radiate.

Fraunhofer lines: Dark absorption lines in the solar spectrum first observed by William Wollaston in 1802. first studied in detail by Joseph Von fraunhofer in 1814, he catalogued over 500 lines and labelled the more prominent ones with letters.

Frequency (v): refers to any periodic phenomenon, particularly to the number of cycles per unit time, measured in Hertz and varies inversely with wavelength.

Ground state: The lowest possible energy level for a given atom or molecule.

HD: Named after Henry Draper, HD is a catalog of spectral types and posi-tions of 225,300 stars numbered in right ascension for 1900 epoch. Compiled by annie Jump Cannon and co-workers at Harvard College observatory between 1918 and 1924, each star is assigned with its own HD number. stars in the range 225,301–359,082 are from the Henry Draper extension catalog denoted HDe published from 1925 through 1936 and 1949.



HR diagram: Hertzsprung–russell diagram in which a star’s absolute mag-nitude is plotted against its spectral type.

Intensity: The amount of radiation received from an object. optical astron-omers prefer the term brightness.

Ion: molecules and atoms that have acquired a positive or negative charge through losing or gaining one or more electrons.

Ionization: a process in which a neutral atom or molecule is given charge by removal of an electron from an atom, ion or molecule by collisians with other atoms or electrons. Because of the high temperatures in stars, much of the matter present is in an ionised state.

Kelvin: a unit of thermodynamic temperature, or the fraction 1/273.16 of the thermodynamic temperature of the triple point of water, denoted by the symbol K. 0 K = −273.16°C absolute zero.

Light: a specific part of the electromagnetic spectrum covering the visible region normally associated with human vision from violet 380.0 nm to red 780.0 nm.

Light year: The distance light travels in a vacuum in 1 year. Numerically equal to:

63,241 au0.306 pc9,460,730,472,580.8 km

Luminosity: The total energy radiated per second by a star expressed in joules per second, which is determined by its surface area and surface temperature.

Luminosity class: Indicates whether a star is a dwarf, giant, or a supergiant as follows:

Ia Bright supergiantsIb supergiantsII Bright giantsIII GiantsIV sub giantsV main sequence dwarfs



for the spectrum descriptors, the suffix is placed after the luminosity class descriptor, i.e., Iae. suffixes for emission lines:

e emission line starem emission by metal linesep Peculiar emissioneq P Cygni emissioner reversed emissionf Helium and Nitrogen emission

other suffixes:k Interstellar linesm strong metallic absorptionn Nebulous diffuse linesnn Very diffuse linesp = pec Chemically peculiar spectrum no luminosity class assigneds sharp linessi silicon starv Variation in the spectrum not caused by velocity effectswk Weak lines

Magnitude: a logarithmic measure of the brightness of an object.

apparent magnitude (m) is a measure of its relative brightness as if seen by an observer on earth. for example, the apparent magnitude of the sun is –26.74.

absolute magnitude (M) is the apparent magnitude it would have if it were at a standard luminosity distance of 10 parsecs from the observer, allowing the true brightness to be compared without regard to distance. The abso-lute magnitudes of most stars are between –5 and +15.

Main sequence: a diagonal region in the Hertzsprung–russell diagram that contains about 90% of all stars. stars on the main sequence are those converting hydrogen into helium in their cores.

Main sequence star: one of the classes of stars that increase in size, tem-perature, and brightness in a regular progression, e.g., the sun. Its luminosity class suffix is V in the mK spectral classification (see below).



Metallicity: The proportion of matter in an object made up of chemical elements other than hydrogen or helium. astronomers label all heavier elements “metal.” for example, a star rich in carbon would be called “metal rich” even though carbon is not a metal.

MK system: The morgan–Keenan system for classifying stellar spectra. Introduced in 1943.

Monochromatic light: light of one wavelength, e.g., a green laser beam has a wavel length of 532 nm.

Nanometer (nm): a unit of length. 1 nm = 10−9 m = 10 Å.

Nuclear fusion: a process by which stars generate energy. The nucleus of an atom fuses with the nuclei of other atoms, producing heavier atoms and releasing large amounts of energy. In the sun, hydrogen is converted into helium.

Objective prism: a small-angle prism placed in front of a telescope objec-tive to disperse each star image into its spectrum.

Photon: electromagnetic energy is produced in discrete small quantities called photons. Photons produced at a particular frequency all have the same energy. The amount of energy present depends on the frequency of the radiation.

Photosphere: The bright visible region of a star’s atmosphere where spec-tral lines are produced.

Prism: a transparent piece of glass with flat polished surfaces that ref-ract light. The dispersion is nonlinear, blue light is bent more than red light. There are four types of dispersive prism: triangular, abbe, Porro, and Porro–abbe.

Radial velocity: The velocity of a star along the line of sight of an observer calculated from the Doppler shift in the spectral lines. If the star is reced-ing, there will be a red shift in its spectral lines, and the radial velocity will be positive. an approaching star will produce a blue shift, and the radial velocity will be negative, measured in Kms–1.



Rest wavelengths: Those wavelengths measured from a source at rest in the laboratory (as opposed to Doppler shifted wavelengths from a moving source).

Right ascension (RA a): a coordinate used with declination in the equatorial coordinate system comparable to longitude, expressed in hours (h), minutes (min) and seconds (s), from 0 to 24 h. measured eastward from the vernal equinox, uniquely identifying the position of a star in the sky. The effect of precession means it must be specified with reference to a particu-lar epoch, currently J2000 January 1, 2000, at 12.00 UT1. The prefix J indi-cates a Julian epoch.

Spectral line: a radiative feature observed in absorption (dark) or emis-sion (bright) at specific frequencies or wave lengths, produced by atoms or ions as they absorb or emit light.

Spectral type: The different groups into which stars may be classified according to the characteristics of their spectra. The surface temperature of a star may often be inferred from its spectral type, as follows:

W 30,000–70,000 Ko 28,000–50,000 KB 9,900–28,000 Ka 7,400–9,900 Kf 6,000–7,400 KG 4,900–6,000 KK 3,600–4,900 Km 2,000–3,600 KC-r 2,800–5,100 K (Carbon star equivalent of late G/early K)C-N 2,600–3,100 K (Carbon star equivalent of late K/early m)s <2,000 K (late-type giant star showing zirconium oxide bands)l 1,300–2,000 K (Dwarf with spectrum showing metal hydrides and

alkali metals)T 770–1,000 K (Dwarf with prominent methane bands in its

spectrum)y <700 K (Hypothetical convincing examples have yet to be

observed)

In general, the temperature of a star is estimated from its B–V color index (after correction for any reddening caused by the interstellar medium).



This works because stars radiate approximately like blackbody emitters. most of the temperatures quoted in the properties tables are accurate to within ±10%. The temperatures of the cooler stars are estimated from their infrared spectra, because these stars are very faint in the B and V bands.

Spectrogram: a photographic or digital image of a spectrum.

Spectral line: a radiative feature observed in absorption (dark) or emission (bright) at specific frequencies or wave lengths, produced by atoms or ions as they absorb or emit light.

Spectrograph: an instrument that splits light or other electromagnetic radiation into its individual wavelengths and records the resulting spec-trum photographically or digitally.

Spectroheliograph: an instrument used to image the sun at particular wavelengths to observe features normally lost in the total spectrum of radiation emitted, such as the calcium H 396.8 nm and K 393.4 nm and the hydrogen alpha 656.3 nm lines.

Spectrohelioscope: The optical counterpart of a spectroheliograph.

Spectrometer (optical): an instrument that produces a spectrum, which can be measured by scanning along its dispersion.

Spectrophotometer: a sophisticated spectrometer for studying infrared, visible, and ultraviolet regions, with devices for automatic measurement and recording of spectra.

Spectroscope: a device usually consisting of a prism or diffraction grating that can disperse a beam of light into its component wavelengths.

Spectroscopic binary: a binary star in which the orbital motions of the components show detectable variations in radial velocity, revealed by changes in the Doppler shift of their spectral lines.

Spectroscopic parallax: a method of determining stellar distances for a group of stars based on their magnitudes and spectral types.



Spectroscopy: The study and interpretation of spectra that can reveal information about the chemical abundances, temperature, radial velo-city, rotation, magnetic field, steller density and pressure, etc. of a light source.

Spectrum: an array of six colors (violet–blue–green–yellow–orange–red, or rainbow) obtained by dispersing light through a grating or prism.

Speed of light (c): measured in a vacuum, c has the value 299,792,458 m/s. (The speed of light is now fixed so this is, in effect, a definition of the meter).

Star: a luminous ball of plasma that creates and emits its own radiation through nuclear fusion, by combining two or more atomic nuclei into a more complex, heavier nucleus in the stellar core.

Stark–Lo Surdo broadening effect: Co-discovered in 1913, this is the shift-ing and splitting of a spectral line by an electric field and is responsible for pressure or broadening of a spectral line by charged particles.

Temperature: astronomical temperatures are usually measured from spec-troscopic observations. astronomical bodies do not generally have a uni-form temperature distribution, so they do not exactly obey the temperature laws, hence there are different types of temperature characterising a par-ticular property of the body with slightly different values, effective-colour-brightness-ionization and excitation temperatures.

Ultimate/resonance lines: The last lines to disappear in the spectrum of an element when the quantity of the element is diminished indefinitely.

Wavelength: The distance from crest to crest or trough to trough of an electromagnetic or other wave. Wavelength is related to frequency. The longer the wavelength, the lower the frequency.

Zeeman effect: observed when atoms are subjected to a powerful mag-netic field, resulting in a spectral line being split into several components. measured by calculating the difference between right and left hand polari-zation across the spectral line.


fUrTHer reaDING

aller, l. H., Atoms, Stars and Nebulae, Third edition, Cambridge University Press, 1991.

Bell Burnell, J. s., s. f. Green, B. W. Jones, m. H. Jones, r. J. a. lambourne, J. C. Zarnecki, An Introduction to the Sun and Stars, Cambridge University Press, 2003.

Brandt, J. C., r. D. C. Chapman, Introduction to Comets, Cambridge University Press, 1982.

Daish, C. B., Light to Advanced and Scholarship Level, The english Universities Press, 1963.

Gray, D. f., The Observation and Analysis of Stellar Photospheres, Third edition, Cambridge University Press, 2005.

Hearnshaw, J., The Analysis of Starlight, Cambridge University Press, 1990.Hearnshaw, J., Astronomical Spectrographs and Their History, Cambridge

University Press, 2009.Hentschel, K., Mapping the Spectrum, oxford University Press, 2002.Herzberg, G., Atomic Spectra and Atomic Structure, Dover, New york, 1944.Hynek, J. a., Astrophysics, mcGraw-Hill, New york, 1951.Inglis, m., Observer’s Guide to Stellar Evolution, springer, 2003.Inglis, m., Astrophysics Is Easy!, springer, 2007.Kaler, J., stars and Their Spectra, Cambridge University Press, 1989.Kaler, J., Extreme Stars, Cambridge University Press, 2001.Kaler, J., The Cambridge encyclopedia of stars, Cambridge University Press,

2006.Kitchen, C. r., Optical Astronomical Spectroscopy, Institute of Physics Publishing,

1995.Krogdahl, W. s., The Astronomical Universe, macmillan, 1952.lang, K.r., The Cambridge encyclopedia of the sun, Cambridge University

Press, 2001.loden, K., l. o. loden, U. sinnerstad, Spectral Classification and Multicolour

Photometry, International astronomical Union, 1966.malpas, D. B., The Bright Star Spectra Index, Draft 9205.1, rainbow optics news-

letter, July 3, 1995.martin, J., a mathematical method for identifying lines in stellar spectra, J. Br.

Astron. Assoc. 109(1), 1999, 22–24.moore, C. e., A Multiplet Table of Astrophysical Interest, NBs Technical Note, 36,

United states Department of Commerce, revised edition, 1972.motz, l., a. Duveen, Essentials of Astronomy, Blackie, london, 1966.Noakes, G. r., Textbook of Light, macmillan, 1946.North, G., Advanced Amateur Astronomy, second edition, Cambridge University

Press, 1997.Palmer, C., Diffraction Grating Handbook, richardson Grating laboratory,

rochester, Ny, 2000.robinson, K., Spectroscopy: The Key to the Stars, springer, london ltd., 2007.sawyer, r. a., Experimental Spectroscopy, Dover, New york, 1963.

Further Reading 199


200 Further Reading

scheiner J., A Treatise on Astronomical Spectroscopy, Ginn, london, 1898.smith-Dibon, r., Starlist 2000, Wiley, 1992.straughan, B. P., s. Walker, Spectroscopy, Volume 3, Chapman & Hall, 1976.Tennyson, J., Astronomical Spectroscopy – An Introduction to the Atomic and

Molecular Physics of Astronomical Spectra, Imperial College Press, 2005.Thackeray, a. D., Astronomical Spectroscopy, eyre & spottiswoode, london,

1963.Tonkin s. f., D. randell, J. martin, N. Glumac, s. J. Dearden, D. e. mais, T. Kaye,

Practical Amateur Spectroscopy, springer, london ltd., 2002.Whiffen, D. H., Spectroscopy, second edition, longmans, london, 1966.

Index

AAbsorption line, 189Angstrom Å, 10, 189Atomic spectra

Balmer series, 189Brackett series, 189Humphreys series, 189Lyman series, 189Paschen series, 189

BB-V color index, 27, 29, 31, 33, 35, 37,

39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 103, 105, 107, 109, 111, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 155, 157, 159, 161, 163, 165, 167, 169

Be type stars, 189, 192Bitmap images, 10Blackbody radiation, 189Blaze angle, 189

CChromosphere, 190Corona, 190ConstellationsContinuum, 190

Aries, 63, 71, 119, 172–175, 181

Pleiades, 183, 184Triangulum, 97, 121, 173, 174, 186

Continuous spectrum, 190

DDeclination, 190, 196Diffraction, 190, 197Dispersion, 190, 195, 197Diurnal motion, 9Doppler broadening, 191Doppler effect, 191Doppler shift, 191, 195–197

EEchelette and Echelle gratings, 191Electromagnetic radiation, 191Electromagnetic spectrum, 191, 193Electron, 189, 191–193Electron volt, 191Emission line, g Cassiopeiae,

172, 189Energy level, 189, 192Excitation, 192

FFlash spectrum, 192Flexible image transport system

(FITS) images, 10Forbidden lines, 192Fraunhofer lines, 194Frequency, 191, 192, 195, 198

202 Index

GGrating, 4, 189–193, 197, 198Greek alphabet, 4, 11Ground state, 192

HHD, Henry Draper catalog, 4, 192Hertzsprung-Russell diagram, 194, 195

IIntensity, 193Ion, 193Ionization, 193IRIS, 10

KKelvin, 193

LLight, 3, 6, 7, 189–191, 193, 195, 196Light year, 193Luminosity, 4, 18–21, 27, 29, 31, 33, 35,

37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 67, 69, 71, 73, 75, 77, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 103, 105, 107, 109, 111, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 155, 157, 159, 161, 163, 165, 167, 169, 181, 190, 193, 194

Luminosity classIa Bright supergiants, 193Ib Supergiants, 193II Bright giants, 193III Giants, 193IV Subgiants, 193V Main sequence dwarfs, 193

MMagnitude

absolute magnitude, 194apparent magnitude, 194

Main sequence, 194Metallicity, 195MK system, 195Monochromatic light, 195

NNanometer, 10, 195Newtonian reflector, 4, 5Nuclear fusion, 195, 198

OObjective prism, 195Olympus OM-1N, 6

PPancromatic films

Fuji Neopan 400–1600, 7, 8Ilford Pan 50 FP4 125 HP5 400

Delta 400-3200, 7Kodak TMAX 98-400-3200, 7Paterson Acupan 200-800, 7

Periodic table of elements, 13–14Photon, 192, 195Photosphere, 195Prisms

Abbe, 195Porro, 195Porro-Abbe, 195triangular, 195

RRadial velocity, 4, 27, 29, 31, 33, 35, 37,

39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 103, 105, 107, 109, 111, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 155, 157, 159, 161, 163, 165, 167, 169, 181, 195, 197, 198

Rainbows optics transmission grating, 4

Index 203

Rest wavelengths, 10, 196Right ascension, 4, 177–179, 190,

192, 196

SSpectra of

a And Alpheratz, 68, 69, 173b And Mirach, 164, 165, 175a Aql Altair, 126, 127, 174z Aql Deneb el Okab, 17341 Ari, 62, 63, 172a Ari Hamal, 160, 161, 175g 1+2 Ari Mesarthim, 70, 173b Ari Sheratan, 118, 119, 174q Aur, 173a Aur Capella, 20, 146, 147, 175b Aur Menkalinan, 106, 107, 173a Boo Arcturus, 175z Cas, 48, 172h Cas Achird, 142, 143, 174b Cas Caph, 132, 133, 174g Cas Cih, 36, 37, 172d Cas Ruchbah, 116, 117, 174e Cas Segin, 52, 53, 172a Cas Shedar, 175a Cep Alderamin, 124, 125, 174b CMa Mirzam, 38, 39, 172a CMa Sirius, 10, 92, 93, 173b CMi Gomeisa, 64, 65, 172a CMi Procyon, 19, 134, 135, 174a CrB Alphecca, 76, 77, 173d Cyg, 80, 81, 173z Cyg, 148, 175a Cyg Deneb, 102, 103, 173e Cyg Gienah, 154, 155, 175g Cyg Sadr, 140, 141, 174z Dra Nodus 1, 54, 55, 172g Gem Alhena, 90, 91, 173a Gem Castor, 94, 95, 173b Gem Pollux, 20, 175z Leo Aldhafera, 174h Leo Al Jabhah, 173q Leo Chort, 173

b Leo Denebola, 174a Leo Regulus, 58, 59, 172d Leo Zosma, 114, 115, 174a Lep Arneb, 130, 131, 174a Lyr Vega, 19, 86, 87, 173e Ori Alnilam, 34, 35, 172z Ori Alnitak, 172g Ori Bellatrix, 18, 172a Ori Betelgeuse, 21, 168, 175d Ori Mintaka, 18, 30, 31, 172a Ori Nair al Saif, 26, 27, 172b Ori Rigel, 66, 67, 173k Ori Saiph, 172g Peg Algenib, 172a Peg Markab, 72, 73, 173h Peg Martar, 144, 145, 175m Peg Sad al Bari, 175b Peg Sheat, 175z Per, 40, 172b Per Algol, 60, 61, 172a Per Mirfak, 136, 137, 174a Tau Aldebaran, 175b Tau El Nath, 56, 57, 172g Tri, 96, 173b Tri Deltotron, 120, 121, 174a Tri Mothallah, 138, 139, 17480 UMa Alcor, 122, 123, 174e UMa Alioth, 88, 89, 173h UMa Alkaid, 50, 172a UMa Dubhe, 158, 159, 175d UMa Megrez, 108, 109, 174b UMa Merak, 98, 99, 173z UMa Mizar A+B, 173g UMa Phecda, 173g UMi Pherkad, 110, 111, 174a Vir Spica, 42, 43, 172

Spectral characteristics, 15–16Spectral line, 197Spectral profiles, 10Spectral sequence, 4, 15–21Spectral types

A, 196B, 196

204 Index

Spectral types (Continued)C-N (Carbon star equivalent of

late K/early M), 196C-R (Carbon star equivalent of late

G/early K), 196F, 196G, 196K, 196L (Dwarf with spectrum show-

ing metal hydrides and alkali metals), 196

M, 196O, 196S (Late-type giant star showing

Zirconium Oxide bands), 196T (Dwarf with prominent methane

bands in its spectrum), 196W, 196Y (Hypothetical, convincing

examples have yet to be observed), 196

Spectrogram, 4, 8–10, 26, 36, 70, 181–187, 197

Spectrograph, 197Spectrometer, 197Spectroheliograph, 197Spectrohelioscope, 197Spectrophotometer, 197Spectroscope, 4, 6, 197Spectroscopic binary, 197Spectroscopic parallax, 197Spectroscopy

composition, 198magnetic fi eld, 198radial velocity, 198rotation, 198temperature, 198

Spectrum 6 colorsblue, 198green, 198orange, 198red, 198violet, 198yellow, 198

Spectrum descriptorse Emission line star, 194em Emission by metal lines, 194ep Peculiar emission, 194m Strong metallic absorption, 194n Nebulous diffuse lines, 194nn Very diffuse lines, 194p = pec Chemically peculiar

spectrum no luminosity class assigned, 194

s Sharp lines, 194si Silicon star, 194

Speed of light, 198Star, 3–198Stark-Lo Surdo broadening effect, 198Summer triangle, 185

TTemperature, 4, 15–21, 27, 29, 31, 33,

35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 103, 105, 107, 109, 111, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 155, 157, 159, 161, 163, 165, 167, 169, 181, 182, 189, 193, 194, 196–198

The Sun, 188

UUltimate/Resonance lines, 198

VVisual Specs, 10

WWavelength, 4, 8, 10, 27, 29, 31, 33, 35, 37,

39, 41, 43, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 103, 105, 107, 109, 111, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147,

Index 205

149, 151, 155, 157, 159, 161, 163, 165, 167, 169, 189–192, 195–198

Winter triangle, 185

ZZeeman effect, 198

ɷ[jack martin] a spectroscopic atlas of bright star

Documents

Transcript of ɷ[jack martin] a spectroscopic atlas of bright star