extra-solar planet populations stephen eikenberry 4 november 2010 ast 2037 1
TRANSCRIPT
![Page 1: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/1.jpg)
Extra-Solar Planet Populations
Stephen Eikenberry
4 November 2010
AST 2037
1
![Page 2: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/2.jpg)
Radial Velocity Planet Searches• So … need a speedometer to measure star velocity versus
time• To a precision of a few meters per second!• Across distances of many light years!!!
2
• How? Doppler shift of spectral lines
![Page 3: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/3.jpg)
51 Pegasi• In 1995, Mayor & Queloz announce the discovery of
an orbital signature with amplitude = 50 m/s in a 4.23-day period around star 51 Pegasi
• Mass = 0.5 MJUP First extra-solar planet
3
![Page 4: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/4.jpg)
51 Pegasi: Hot Jupiter?• At that location, expected
temperature is VERY high (about 2000K or higher!)
• So … Jupiter-like planet, but closer than Mercury “Hot Jupiter”
• How do you make something like that????
4
![Page 5: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/5.jpg)
Planet Bonanza• Geoff Marcy & Paul Butler quickly confirmed 51
Pegasi• They had lots of archival data from searches for
Jupiter-type planets (periods >10 years, so they were still “in progress”)
• No on even thought to look for short-period MASSIVE planets (why would they be easier?)
• Found many “Hot Jupiters” – most extra-solar planets known today are Hot Jupters
5
![Page 6: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/6.jpg)
ES-Planet Population• As of this morning, 228 861 planets are now known to orbit
other stars (!!)• All of this has happened in about 15 years – someone
currently finds a new planet every couple of days or less• These planets are NOT generally like our Solar System
objects – WHY?
6
![Page 7: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/7.jpg)
7
![Page 8: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/8.jpg)
8
![Page 9: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/9.jpg)
9
![Page 10: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/10.jpg)
Upsilon Andromedae• First multiple planet system
10
![Page 11: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/11.jpg)
Upsilon Andromedae• First multiple planet system
11
![Page 12: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/12.jpg)
12
![Page 13: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/13.jpg)
HD 209458• Another Hot Jupiter
13
![Page 14: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/14.jpg)
HD 209458• What is a “transit”?
14
![Page 15: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/15.jpg)
HD 209458• A transit observed• Note: only ~1% dip
15
![Page 16: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/16.jpg)
HD 209458 - Results• Just at the entry moment into transit, for a brief
instant, only the upper atmosphere of the planet absorbs any starlight
• With a powerful enough spectrograph, we can look for absorption lines at this instant
• Result: COMPOSITION of the planet atmosphere• HD 20948b contains – WATER!!
16
![Page 17: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/17.jpg)
Gliese 581c• Low-mass planet, with mass 5 Mearth
• Orbit semi-major axis 0.07 AU• Low-mass star
17
![Page 18: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/18.jpg)
Gliese 581c• Just inside Habitable Zone• Gliese 581d just outside HZ
18
![Page 19: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/19.jpg)
Eccentricity
19
![Page 20: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/20.jpg)
20
Circumbinary Planets
![Page 21: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/21.jpg)
21
Transiting Planets in the HZ
Image Credits: NASA Borucki et al. 2012Orosz et al. 2012
![Page 22: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/22.jpg)
22
![Page 23: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/23.jpg)
Planets in Habitable Zones• Many planets are
currently known in the Habitable Zone around their parent stars
• Most of these are gas giants no solid surface
• But … gas giants in our Solar System have lots of moons
• What happens to Europa if you move it/Jupiter to a distance of 1 AU?
23
![Page 24: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/24.jpg)
Planets in Habitable Zones• What happens to Europa
if you move it/Jupiter to a distance of 1 AU?
• Really?• Europa mass is closer to
our moon’s mass – why no water there?
• So … need giant planets in the HZ with giant moons …
24
![Page 25: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/25.jpg)
25
Our Solar System is Not Typical
• Sun is an unusually massive star• Our solar system has no planets with orbital periods
less than Mercury• Our inner solar system does not have a
super-Earth-size to Neptune-size planet• Most planetary systems don’t have a Jupiter analog
→ Planet formation theories should typically produce planetary systems unlike our own
Borucki+ 2011; Batalha+ 2012; Howard+ 2012; Fressin+ 2013; Burke+ in prep
![Page 26: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/26.jpg)
Terrestrial Planet Finder• Ultra-high-contrast imager satellite• Capable of finding Earth-mass planets in HZ around nearby
stars
26
![Page 27: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/27.jpg)
Summary• We have found hundreds of planets around other stars• Overwhelming majority are massive gas giants, many close
to their parent star• This is because they are easiest to find with the Doppler
technique; but Kepler mission (transits) is changing that• Have found: multiple planet systems (20+); planet
atmospheres; some low-mass (probably solid) planets• Eccentricity seems more common than circular orbits;
problems for life• So far, only a few gas giants in the HZ; first possibly-solid
planets; maybe moons could host life (??)• Future searches will be sensitive to Earth-mass planets in
the HZ
27
![Page 28: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/28.jpg)
Exoplanet Zoo: Examples• We have found
hundreds of planets around other stars
28
![Page 29: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/29.jpg)
Exoplanet Zoo: Examples• Multiple-planet systems
29
![Page 30: Extra-Solar Planet Populations Stephen Eikenberry 4 November 2010 AST 2037 1](https://reader036.vdocuments.us/reader036/viewer/2022062721/56649f255503460f94c3bde9/html5/thumbnails/30.jpg)
Exoplanet Zoo: Examples• OGLE-2005-BLG-390Lb – 5.5 Earth-mass, far from star
(T=-360 ˚F)• COROT-7b: 4.8 Earth-mass, density = Earth-density (!);
close to star (T ~1300K)• Gliese 581g: 3-4 Earth-mass; T ~- 25 ˚F to +160 ˚F; in the
Habitable Zone (!), but tidally locked
30