Extra Solar Planets. The first51 Pegasi b (Bellerophon )
-
Upload
jonathan-cullen -
Category
Documents
-
view
218 -
download
0
Transcript of Extra Solar Planets. The first51 Pegasi b (Bellerophon )
![Page 1: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/1.jpg)
Extra Solar Planets
![Page 2: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/2.jpg)
The first—51 Pegasi b (Bellerophon )
![Page 3: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/3.jpg)
51 Pegasi B
Star51 PegasiConstellationPegasusDistance50.9 ± 0.3 ly(15.61 ± 0.09 pc)Spectral typeG2.5IVa or G4-5VaMass(m)1.06 x Mass of SunRadius(r)1.237 ± 0.047 RsunTemperature(T)5571 ± 102 KMetallicity[Fe/H]0.20 ± 0.0Age6.1-8.1 Gyr
Semimajor axis (a)0.0527 ± 0.0030 AU(7.89 Gm)
Periastron (q)0.0520 AU(7.79 Gm)
Apastron (Q)0.0534 AU(7.99 Gm)
Eccentricity (e) 0.013 ± 0.012
Orbital period (P) 4.230785 ± 0.000036 d
(101.5388 h)
Argument ofperiastron
(ω) 58°
Time of periastron (T0) 2,450,001.51 ± 0.61 JD
Semi-amplitude (K) 55.94 ± 0.69 m/s
Physical characteristics
Minimum mass (m sin i)0.472 ± 0.039 MJ
(150 M⊕)
The planetThe star
![Page 4: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/4.jpg)
How do we know this
Radial velocity of Star
It move toward and away from us with period of 4.2 days.
![Page 5: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/5.jpg)
How do we know that?
Doppler Effect!
Change in wavelength depends on speed!
![Page 6: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/6.jpg)
In practice…its done with spectra
![Page 7: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/7.jpg)
Problem: not all systems are edge on! We don’t always know the tilt!
Thus the mass measured is a minimum mass
Here I = 90..can’t determine mp
Here mp = 0, we can can know exact mass.
In General, mass listed is really: M sin i
where i is inclination of orbit
![Page 8: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/8.jpg)
Then there is a bit more physics:
momentum) ofion (conservat
.
planetplanetstarstar
starp
vmVM
drr
I
ngravitatio universal ofconstant G
axismajor -semi d
period orbitalp
3))(
24(2
d
planetm
starMG
p
ngravitatio universal ofconstant G
axismajor -semi d
period orbitalp
3))(
24(2
.
d
planetm
starMG
p
II
ngravitatio universal ofconstant G
axismajor -semi d
period orbitalp
3))(
24(2
d
planetm
starMG
p
p
rv
p
rv planet
planetstar
star
2 ,
2 IV.
starstarp MMm III.
![Page 9: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/9.jpg)
Then a bit of algebra….and
ngravitatio universal ofconstant G
axismajor -semi d
period orbitalp
3))(
24(2
d
planetm
starMG
p
p! and ,V ,M needonly you so4
2
:is,result
starstar
32
2
3
2
GpMd
G
pMVm
the
star
starstarp
Astronomers know star masses from their spectra and lots of work from predecessors over the years!
Vstar and p are obtained from the radial velocity graph!
![Page 10: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/10.jpg)
Limits of Radial velocity measurements
Star surfaces move up and down about 1 m/s, so this is smallest practical speed for star.
Big Planet close to small star creates the biggest wobble, so we can see these most easily.
To see a complete wobble, we need to watch for one period—hard to do for planets more distant than a few
AU’s. Earth Makes sun move about 1 cm/s, so this would be lost in the Noise of the sun if someone was trying to detect us!
So guess what we found around sun like stars ?
![Page 11: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/11.jpg)
Hot Jupiters!
Here are the first nine planets discovered (as of 1997)
![Page 12: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/12.jpg)
Why search around sun like stars?
![Page 13: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/13.jpg)
A more complete list (2000)
![Page 14: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/14.jpg)
A Growth Industry?
![Page 15: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/15.jpg)
So where are we know (2010)
Note 20 multiple planet systems!
![Page 16: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/16.jpg)
So how are they finding smaller or more distant planets?
Use Astrometry (motion of stars in photographs)
Watch for longer time periods! (its been 12 years now!)
• Improve precision of methods (techology continues to improve)
• Gets lots more people doing it! • Search around smaller stars!
• Use Transit Photometry for edge on systems (finds smaller planets?)
• Lets see how these methods are working!
![Page 17: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/17.jpg)
Astrometry
![Page 18: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/18.jpg)
Transit Photmetry
![Page 19: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/19.jpg)
Provides lots of info!
![Page 20: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/20.jpg)
Not as easy as it looks!
Transit of Venus in 2004Transit of Mercury in 2006
![Page 21: Extra Solar Planets. The first51 Pegasi b (Bellerophon )](https://reader036.fdocuments.us/reader036/viewer/2022062619/55159d46550346a1418b5eda/html5/thumbnails/21.jpg)
Zoom in…
Check out: http://www.esnips.com/doc/868644b5-3d2d-46f7-8497-90255b80e3d7