The 2013 Beatrice Tinsley Lecture: A Zoo of Galaxies
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Transcript of The 2013 Beatrice Tinsley Lecture: A Zoo of Galaxies
The 2013 Beatrice Hill Tinsley Lecture
Dr. Karen MastersUniversity of Portsmouth, UK
A Zoo of GALAXIES
Our galaxy
120 thousand light years
Artist ImpressionCredit: NASAYou are hereEdge-on spiral
NGC 4565 (NOAO)
The Spiral Nebulae
The Andromeda Galaxy
William Herschel c1800
What are these spiral nebula?
Red
Massive
In clusters
Blue
Less massive
Not in clusters
10 m
illion
yea
rs
100
billio
n ye
ars
100
milli
on y
ears
10 b
illion
yea
rs
Galaxies are made of stars
The Colours of Galaxies
Beatrice Tinsley (1941-1981)
Only old stars
Still forming stars
How Many Galaxies Are There?
192924
Distance ->
Vel
ocity
->
How Many Galaxies Are There?
19861,110
20081 million
Sloan Digital Sky Survey (2012)
Colour Magnitude Diagram
Mass (Luminosity/magnitude)
Blu
erR
edde
r
CO
LOU
R
Bigger/brighterSmaller/dimmer
Red sequence – ellipticals
Blue cloud
– spiral galaxies
Mass division
Green valley (very sparse)
Big DataRed sequence - ellipticals
Blue cloud - spirals
How to look at a million galaxies – ask for help!
Big DataRed spirals!
Blu
e el
liptic
als!
Elliptical
galaxies
Spiral galaxies
Red Spirals
Bamford et al. 2009; Skibba et al. 2009Masters et al. 2010a,b
Some galaxies appear to be
crashing into each other.
High Velocity Clouds and the Milky Way Credit: B. Wakker et al. and NASA
Galaxy Zoo 2
Take the brightest ¼ million galaxies and ask more detailed questions (Feb 2009-April 2010)
Red Spirals have more
bars
Do bars kill galaxies?Blue = bars rare
Red = bars more common
Blue Red
Masters et al. 2011 MNRAS
More bars where there’s less gas
0.01 0.1 1.0 10.0Gas fraction (MHI/M★)
Masters et al. 2012 MNRAS
Atomic HI (Walter et al. 2008)
Optical from SDSS (DR8)
Molecular H2 (Helfer et al. 2003)
The bar and gas in Messier 95
What’s next for the Zoo?
Galaxy Zoo is Popular
Why Do People Do This?
Galaxy Zoo: Exploring the Motivations of Citizen Scientists. (Raddick et al. 2009 astroph/0909.2925)
.org
Six years of Galaxy Zoo
• July 2007-Feb 2009• Original Galaxy Zoo (spiral vs elliptical, SDSS)
• Feb 2009-April 2010• Galaxy Zoo 2 (detailed morphology, SDSS)• Zooniverse launch (Dec)
• April 2010 – Aug 2012• Galaxy Zoo: Hubble
• Aug 2012 - ?• Galaxy Zoo relaunched (more Hubble, more SDSS)
• Aug 2013 - ? • Galaxy Zoo: Quench launched
Credit: Alice Sheppard