Presentation is loading. Please wait.

Presentation is loading. Please wait.

Extra-Solar Planets Planetary Physics Summer Term 2004 Lecture 10.

Similar presentations

Presentation on theme: "Extra-Solar Planets Planetary Physics Summer Term 2004 Lecture 10."— Presentation transcript:

1 Extra-Solar Planets Planetary Physics Summer Term 2004 Lecture 10

2 Or: How to get on the Big Breakfast Show...

3 Extra-Solar Planets Since October 1995, more than 120 planets have been detected around more than 100 stars like the Sun - why the sudden success? None has been seen directly: all found by wobble of parent star caused by orbiting planet - how? None is like the Earth: all have masses more like Jupiter - why?

4 Extra-Solar Planets Definitions: Star: > 0.08 solar masses (80 jupiter masses), powered by H fusion; formed by gravitational collapse, occur singly or in multiples Brown Dwarf: 13 jup < mass < 80 jup, some initial D fusion, then fade; formation and occurrence as normal stars Planets: < 13 jup, no nuclear power source; formed by accretion from protoplanetary disc left behind from formation of parent star

5 In these HST pictures we see disks around stars, but also jets of material being blown out again, especially in the lowest picture (the Rotten Egg nebula). Planets form from the disks.


7 Extra-Solar Planets Methods of detection: Astrometry - long history, no detections Radial velocity surveys - very successful Brightness variations –planet passes in front of star: drop in brightness –gravitational lensing of star by planet: increase in brightness - only way to detect earth-mass planets Interferometry - ground and space missions

8 Extra-Solar Planets Astrometry: Very precise measurements of position of parent star, relative to inertial frame, repeated over many years Centre of mass of system moves in straight line If planet exists, stars motion will have slight wobble about CoM motion - can find size and period of orbit, and mass of planet Massive planets in wide, long-period orbits give largest wobble; nearby stars are best, but effects still too small to measure with present equipment

9 Extra-Solar Planets Radial velocity surveys: Very precise measurements of radial velocity of parent star, using doppler effect Single star will have constant velocity, but if companions are present their orbital motions will be reflected in motion of star about CoM - look for periodic oscillations in radial velocity

10 Extra-Solar Planets Limits of radial velocity measurements: Can find period, eccentricity and M P sin i, where i is inclination of orbit to line of sight (just measure the radial velocity, = V 1 sin i, where V 1 is the orbital motion of the star – see Lecture 5) Can not measure i : need transits for this Motion largest for large masses, short periods Limit set by oscillations in stars size (2-3 m/s) Earth mass in 1-yr orbit gives only 0.1 m/s

11 Extra-Solar Planets Gravitational lensing: Parent star (lens) focuses light of background star as it passes in front of it: Observer Star Lens (and planet) time Planet causes blip in slow light variation

12 Micro-lensing simulation

13 Extra-Solar Planets History I: : various false astrometric claims of Jupiter size companions, e.g. to Barnards star (van de Kamp) 1980s: pioneering radial velocity survey by Campbell & Walker - precision of 13 m/s, but no detections (small sample - only 21 stars)

14 Extra-Solar Planets History II: Late 1980s, early 1990s: several large, high precision RV surveys began - Marcy & Butler (Lick), Mayor & Queloz (OHP), Cochran & Hatzes (McDonald) 1995 October 6: first extrasolar planet round a normal star announced by Swiss team (2 found earlier around a pulsar)

15 Marcy and Butler found this wobble in the motion of the star 51 Pegasi, and were able to find a period of just over 4 days.

16 This shows the same observations, but now with all the different orbits superimposed to show the variation better.

17 Extra-Solar Planets What did we expect? small mass planets (Earth-like) close to star: radiation should evaporate most abundant element, hydrogen, leaving small rocky planets massive gaseous planets (Jupiter-like: mainly hydrogen) far enough out to avoid evaporation - so expect long periods circular orbits, as in solar system stars like the Sun

18 Extra-Solar Planets What did we find? massive planets close to star! many eccentric orbits! no earth-like planets stars generally richer in heavy elements (such as iron) than the Sun Of the more than 100 found so far, at least 10 of the early one were around targets suggested by Kevin Apps (Sussex u.g.)

19 Extra-Solar Planets Kevins involvement: November/December ed Marcy requesting list of 300 targets for Keck 10-m, found 30 unsuitable and suggested 30 replacements Became responsible for generating new targets (in 1999, nearly 400 of the 900 targets were his) and for searching the literature for their properties April 1999: went to San Francisco to observe with a Lick Observatory telescope August 1999: observed on Hawaii (Keck) May do PhD with Marcy from 2004

20 Extra-Solar Planets Current results: 122 planets with masses 0.12 to 16.9 jup 41 hot Jupiters (Jupiter mass, close to star: a < 0.4 AU) 57 Jupiter analogues (Jupiter mass, far from star: P > 1 yr) 70 eccentric planets (high eccentricity orbits: e > 0.2) 13 systems with multiple planets (2 have 3)

21 The first 22 planets were very close to their parent stars

22 Three planets around Upsilon Andromedae: first solar system

23 Extra-solar Planets Catalog Including Candidates to be confirmed (sorted by increasing mass) From the Extrasolar Planets Encyclopaedia Extrasolar Planets Encyclopaedia Maintained by ©,1996 Jean Schneider Observatoire de Paris ©,1996 Jean Schneider Update: 10 May 2001 ( Warning: As there is no clear consensus about the definition criteria of planets, `super-planets' and brown dwarfs (mass, formation,...), this Catalog includes only (with a few exceptions) objects lighter than 13 M Jup (no deuterium burning)). The Catalog below contains four tables (the objects are sorted for each by increasing mass of the lightest planet in the system): 1.Confirmed planets around main sequence stars 1.HD update 2 Nov. 00HD HD update 22 Nov. 00HD HD update 4 May 00HD HD update 29 Mar. 00HD HD update 4 May 00HD HD update 16 Apr. 01HD Peg update 16 Apr Peg 8.BD update 27 Apr. 00BD HD 6434 update 22 Nov. 00HD HD update 6 Jul. 00HD HD update 25 Apr. 01HD upsilon And update 7 May. 01upsilon And 13.HD update 22 Nov. 00HD epsilon Eridani update 27 September 00epsilon Eridani 15.HD update 22 Nov. 00HD HD update 20 Apr. 01HD Cnc update 22 Nov Cnc 18.HD update 10 May. 01HD HD update 21 August 00HD HD update 22 Nov. 00HD HD update 30 Mar. 00HD rho CrB update 6 Apr. 01rho CrB 23.HD update 22 Nov. 00HD HD update 22 Nov. 00HD HD update 6 Jul. 00HD HD update 22 Nov. 00HD HD update 16 Dec. 00HD Cyg B update 18 Jan Cyg B 29.HD update 4 Apr. 01HD HD update 22 Nov. 00HD HD update 16 Dec. 00HD HD update 21 August 00HD Gliese 876 update 7 May. 01Gliese HD update 22 Nov. 00HD HD 8574 update 4 Apr. 01HD HR810 update 22 Nov. 00HR Uma update 22 Nov Uma 38.HD update 22 Nov. 00HD HD update 22 Nov. 00HD Her update 16 Apr Her 41.GJ 3021 update 22 Nov. 00GJ HD update 4 Apr. 01HD HD update 22 Nov. 00HD HD update 4 Apr. 01HD Gl 86 update 22 Nov. 00Gl tau Boo update 16 Dec. 00tau Boo 47.HD update 4 Apr. 01HD HD update 22 Nov. 00HD HD update 11 Jan. 01HD HD update 22 Nov. 00HD HD update 4 Apr. 01HD HD B update 4 Apr. 01HD B 53.HD update 22 Nov. 00HD Vir update 22 Nov Vir 55.HD update 4 Apr. 01HD HD update 22 Nov. 00HD HD update 4 Apr. 01HD HD update 22 Nov. 00HD Confirmed planets around pulsars 1.PSR update 28 Mar. 01PSR PSR B update 29 July 99PSR B Disks (potentially protoplanetary or associated to planets) (sorted by distance to the Sun) 1.Beta Pictoris update 2 Sep. 98Beta Pictoris 2.L 1551 update 2 Oct. 98L BD +31 o 643 (disk; to be confirmed) update 10 mar. 97BD +31 o Unconfirmed, doubtful, unpublished or invalidated objects. 1.W 3 (OH) update 28 Oct. 99W 3 (OH) 2.HR7875 update 15 Jul. 1998HR Geminga (invalidated) update 8 Sep. 99Geminga 4.PSR (Very doubtful) update 28 Apr. 99PSR PSR (unpublished data)PSR Q A (to be confirmed)Q A 7.Lalande (data unpublished) update 5 dec. 97Lalande CM Dra (to be confirmed) update 25 mar. 00CM Dra 9.Alpha Tau (to be confirmed) update 4 Dec. 97Alpha Tau 10.TMR-1C (invalidated) update 3 Apr. 2000TMR-1C BLG-35 (to be confirmed) update 7 mar BLG BLG-3 (to be confirmed) update 23 dec BLG BLG-41 (to be confirmed) update 4 nov BLG BLG-4 (to be confirmed) update 23 dec BLG stars with NO planet found (Walker et al.)NO planet found 1.- Confirmed planets (and/or brown dwarfs) (note 1: for planets detected by timing and radial velocity, only the product M x sini is known) 2.- Confirmed pulsar planets StarM[.sini] Jup. mass:(J) Earth mass:(E) (note 1) Semi- maj. Axis (AU) Period years(y) days(d) Ecc.Incli n. (deg) Radiu s (Earth rad.) PSR PSR ~ 300 pc (E) 3.4 (E) 2.8 (E) ~ 100 (E) ~ (d) (d) (d) ~ 170 (y) PSR B PSR B kpc 1.2 < M.sini < 6.7 (J) (y) Unconfirmed, doubtful or unpublished objects StarM[.sini] Jup. mass:(J) Earth mass:(E) (note 1) Semi-maj. Axis (AU) Period years(y) days(d) Ecc.Incli n. (deg) Radi us (Eart h rad.) HR7875 HR pc F8V V = (J)-42.5 (d) PSR PSR kpc 3 (E) 12 (E) 8 (E) (y) 1.35 (y) 2.71 (y) Q Q Gpc (z = 0.39) ~ a few (E) Lal Lal pc M2 V = (J) (y) 30 ? (y)--- CM Dra CM Dra 14.7 pc M4.5/M4. 5 V = Alpha Tau Alpha Tau pc K5III V = (J) (d)0.182 # ?- TMR-1C TMR-1C ~130 pc V = ? 2- 3 (J) ?> 1,500> 40,000 (y) ??~1 R J 98-BLG BLG- 35 ~ 5 kpc ~ (E) 1.5 or 2.3???- 95-BLG-3 95-BLG-3 ~ 5 kpc ~ 2 (J)> ? BLG-4 94-BLG-4 ~ 5 kpc ~ 5 (J)~ Beta Pic Beta Pic 18 pc A5V V = 3.8 -> (d)-< 1 o ~ 16 BD +31 o 643 BD +31 o pc B5V, B5V V = 8.5, 8.5 diskrad. disk: 6,600 --< 10 o - W 3 (OH) W 3 (OH) 3 kpc pc O8 star V = ? ? (E)2,000?---- Back to the Extra-solar Planets Encyclopedia The majority of the planets found so far have orbital radii less than 1 AU: 35% of them are less than 0.4 AU, although there is a growing number with larger radius, including one beyond Jupiter.

24 The majority of planets (~60%) have masses between 1 and 8 Jupiter masses, but there are now many known (~30%) with masses less than that of Jupiter (down to 0.12 jup: ~0.4 sat). But only lower limits are known without knowing i: needs transits. Mass distribution for extra-solar planets

25 7 November 1999: first-ever planetary transit observed for sun-like star HD by Henry, Marcy, Butler and Vogt

26 The radial velocity group of Marcy, Butler and Vogt found this evidence of a wobble in the motion of the star and alerted Greg Henry to observe its brightness.


28 This is the 0.8m Automatic Photoelectric Telescope of the Tennessee State Universitys Fairborn Observatory in southern Arizona, which was used by Greg Henry to observe the planetary transit. An attempt to verify the result on November 14 was clouded out, but other groups later verified it.

29 Average of four HST transit observations

30 Three more transits have now been detected, in the microlensing surveys, and one genuine microlensing event: One of the three transit events…. ….and the microlensing event

31 Extra-Solar Planets The Future: Continuing radial velocity searches (lower mass planets? more solar systems?) Transits – now four cases Gravitational lensing Ground-based astrometry Direct imaging? Difficult from the ground Space-based imaging (e.g. DARWIN) Space-based astrometry (e.g. GAIA)

32 An artists impression of the proposed 6-spacecraft Darwin mission, due to fly in about Each craft contains a large IR telescope, and they are spread over distances of 40 to 500 metres.


34 Extra-Solar Planets Where next? Who knows!

Download ppt "Extra-Solar Planets Planetary Physics Summer Term 2004 Lecture 10."

Similar presentations

Ads by Google