Variable Stars and Their Light Curves Arne Henden Director, AAVSO [email protected].
Variable Stars and the AAVSO Arne Henden Director, AAVSO [email protected].
45
-
Upload
collin-maxwell -
Category
Documents
-
view
243 -
download
0
Transcript of Variable Stars and the AAVSO Arne Henden Director, AAVSO [email protected].
Variable Stars
• Every star varies during its lifetime• Physical variation (pulsation, spots) tell us
about stellar structure, cosmology• Geometrical variation (binaries) give us
masses, densities, sizes• Accretion disk phenomena prevalent at all
scales• Transient events (novae, supernovae,
gamma-ray bursts) detail stellar evolution• If you are an astronomer, you will study
variable stars sometime during your career• This is where the AAVSO enters the picture!
The American Association of Variable Star Observers (AAVSO)• Dedicated to the study of variable stars• One of the largest & oldest Citizen Science
organizations in the world• International: 1000 members in 45 countries• 15% professional, 85% amateur members• 3000 total observers (800 active per year)• 23 million online observations• http://www.aavso.org
Cumulative observations in AAVSO International
Database(current rate: 1.5M/year)
AAVSO HQ 2km from Harvard/CfA
Today’s Observers
Comet PanSTARRschanging tail structure
total brightnessnuclear brightness
rotation periodjet activity
Comet ISON due in 2014
Credit: Lorenzo Comolli
Amateur spectroscopic setup
PanSTARRsbright comets can be
observed with amateur spectrographs
Lunar photosgood test target
videocam impactsLCROSS
T Pyx latest
Artist’s conception of the T Pyx system (orbit size of moon’s orbit)
T Pyx latest
T Pyx latest light curve
T Pyx visual and Xray comparison
T Pyx 400-900nm outburst spectrum
T Pyx Halpha hires spectrum
M101 + SN2011fe
Credit: Albert Duin
SN2011fe latest light curve
SN2012aw in M95
SN2012aw light curve
M65 supernova SN2013am
Credit: Wendel & Masi
Amateur Spectroscopy
• http://astrosurf.com/buil/saintcaprais/first.htm
• Observatoire de Saint-Caprais Rabastens (Tarn)
• Yvon Rieugné et Pierre Thierry
Thierry’s 94cm
SN2011fe spectrum
MASTER OT J095310.04+335352.8 LP binary or RCB?
Denisenko et al. ATEL 4784 Credit: ASAS
GR Ori05:21:34.98 +01:10:10.2
WZ Sge; last outburst 1916
AZ Cas
Cookbook for VS observing
• Use VSX or AAVSO Campaigns, observing programs to select object; http://www.aavso.org/vsx
• Example: V435 Cam– 06:15:20.90 +82:08:13.4 J2000– 13.7 – 14.1 R– Period 112 minutes
Generate finding chart
• http://www.aavso.org/vsp • DSS option gives true sky view
Acquire data
• 111min period; use 50pts/period or one every 2 minutes
• Best if use both B&V, but use at least one filter
• Cover entire cycle ++ if possible
Process data
• Dark subtract and flat field
• Extract photometry using sequence to get standardized magnitudes
• Output in AAVSO Extended format if possible
Analyze data
• Spreadsheet with the correct period
• Use VSTAR for phase plotting and period analysis:
• http://www.aavso.org/vstar
Submit data
• Get an AAVSO observer code: http://www.aavso.org/request-obscode
• Use Webobs to upload your data:
• http://www.aavso.org/webobs
Variable stars are for you!
• Easy to observe
• Good subjects for research
• Collaborate with professionals
• Can use naked eye, binoculars, DSLR, telescope+CCD, spectrograph, etc.
• Manuals/tutorials on AAVSO web site
• You too can do cutting-edge science!
AAVSO news
2GSS features
• Immediate public access• Simultaneous color information• Prototype fully funded• Fwhm smaller than existing surveys• Entire sky covered, including galactic plane (50
million stars per night)• Long life-time (AAVSO)• Pathfinder for LSST
2GSS specs
• Prototype to be installed at Lowell Observatory in June 2013
• Use of APASS for field secondary standards• Phase I has photometry available within
24hrs, public, on-line• Phase II incorporates real-time alerts
2GSS telescope
Anderson Mesa Dark Sky Site (Flagstaff, AZ)
2GSS site
Impact on CCD Observers
• Real-time alerts need to be followed up• Photometry degrades below ~15th; provide
higher-quality photometry• One-day cadence poor for short-period
variables, transient objects• Only V,I’ photometry, so other wavelengths
needed
Impact on Visual Observers
• Real-time alerts need to be followed up• One-day cadence poor for short-period variables,
transient objects; little change for CV observers• Saturates at V=10-11; no coverage of brighter objects• Will have problems with moon; won’t go near
horizons; blended objects difficult• Starting in 2012, but not fully operational until 2013,
and then only if fully funded
LP binary or RCB?
