Observations of Extrasolar Planets

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1 Observations of Extrasolar Planets Hamilton 2005 Shay Zucker

2 Observations of Extrasolar Planets Spectroscopic detection of exoplanets Emerging properties of the sample Transiting planets Future prospects

3 Observations of Extrasolar Planets Spectroscopic detection of exoplanets Emerging properties of the sample Transiting planets Future prospects

4 How difficult is direct detection? d 01 5 ~ 10 d12 d12= 5 AU p 0 =1 s c e ars d 01 L* 8 9 ~ Lp

5 Indirect Detection Newton s 3rd law: The attraction is mutual the planet also pulls the star the star also performs an orbital motion (albeit much smaller) We try to detect this motion

6 Spectroscopy and Radial Velocities

7 Spectroscopy and Radial Velocities Stellar Spectrum

8 Spectroscopy and Radial Velocities A moving source of radiation The waves in front of the source are squeezed shorter wavelengths The waves behind have longer wavelengths Doppler Effect a tool to measure radial velocities

9 Planets Detected through Radial Velocities L to observer Radial Velocity P i v K Time K P 1 day 1 3 M star M sun 2 M planet sin i 3 M Jup 203 m s -1

10 The M sin i problem We can only measure M sin i However, f (sin i) assuming isotropy: sin i sin i 1

11 Leading Figures Geoff Marcy Michel Mayor Berkely Genève

12 HD b Latham, Mazeh, Stefanik, Mayor & Burki 1989, Nature, 339, 38 M sin i 9 1 M Jup P days Precision: ~ 500 m s -1

13 51 Peg b Mayor & Queloz 1995, Nature, 378, 355 Spectrograph: ELODIE M sin i M Jup P days A Hot Jupiter

14 Observations of Extrasolar Planets Spectroscopic detection of exoplanets Emerging properties of the sample Transiting planets Future prospects

15 Hot Jupiters So far, ~20 Hot Jupiters discovered Appeared to contradict the snow-line paradigm Proposed solution: giant planets form outside the snow-line and migrate inwards.

16 Another Surprise: Eccentric Orbits 70 Vir 16 Cyg B HD80606 e 0.93 e 0.40 e 0.63 Marcy & Butler 1996 Cochran et al Naef et al. 2001

17 Planet Mass Distribution The Brown-Dwarf Desert Planet mass distribution falls off at ~10 Jupiter masses. Zucker & Mazeh 2001

18 Planet-Metallicity relation More planets are detected around metal-rich stars. Santos et al. 2003

19 Mass-Period Relation Very massive planets are not found in shortperiod orbits Zucker & Mazeh 2002

20 Planets in Binary Stars HD41004: A wide binary system that hosts a brown dwarf and a planet Zucker et al. 2004

21 Planetary Systems Marcy et al. 2001

22 Neptunian Mass Planets HARPS μ Arae Precision ~1 m s-1 Santos et al. 2004

23 Observations of Extrasolar Planets Spectroscopic detection of exoplanets Emerging properties of the sample Transiting planets Future prospects

24 Extrasolar Planetary Transits Venus Transit June 2004

25 Extrasolar Planetary Transits The inclination (i) must be very close to 90 Probability is highest for close-in planets

26 HD Mazeh et al. 2000, The Astrophysical Journal Letters, 532, L55 M sin i M Jup P days A Hot Jupiter

27 HD Transit Charbonneau, Brown, Latham & Mayor 2000, The Astrophysical Journal Letters, 529, L45 Henry, Marcy, Butler & Vogt 2000, The Astrophysical Journal Letters, 529, L41 Periodical dimming of the star s light Same period as the radial velocities Depth: ~1.5% Duration: ~2.5 hours

28 Transit Shape What can we learn from the transit shape: Inclination Planet radius Stellar radius

29 HD Brown, Charbonneau, Gilliland, Noyes & Burrows 2001, The Astrophysical Journal, 552, 699 Hubble Space Telescope Rplanet RJup i g cm 3

30 Atmospheric Absorption of HD Na Charbonneau et al H Vidal-Madjar et al C, O Vidal-Madjar et al. 2004

31 Thermal Emission from HD209458b Stay tune d for J Rich e re m ardso y n s t alk

32 Transit Surveys Transit existence depends strongly on geometry (i) Survey has to cover a dense field Detection is a computational challenge RV follow-up is essential for final proof Currently, 6 bona-fide transiting planets are known

33 Mass-Radius Relation Pont et al. 2004

34 Observations of Extrasolar Planets Spectroscopic detection of exoplanets Emerging properties of the sample Transiting planets Future prospects

35 Other Techniques Planets around pulsars Direct imaging Astrometry (interferometry) Coronography Gravitational micro-lensing Chauvin et al. 2005

36 Observational Challenges Ahead Detect more planets (enhance the statistics) Detect smaller planets (the aim earth sized!!) Detect planets directly Spectroscopy of planets Life markers!!

37 Planned Space Missions COROT, Kepler: search for transits of earth-sized planets Darwin, TPF: direct detection of earth-sized planets Gaia, SIM: micro-arcsecond astrometry, looking for wobble

38 Observations of Extrasolar Planets Spectroscopic detection of exoplanets Emerging properties of the sample Transiting planets Future prospects