Planet 51 Peg b

Detailed information about planet 51 Peg b and its parameters.

Planet

Name
51 Peg b
Planet Status
Confirmed
Discovered in
1995
Update
2024-09-01
Mass
0.47 ( +0.03 -0.07 ) MJ
Mass*sin(i)
Semi-Major Axis
Orbital Period
Eccentricity
ω
Tperi
Radius
Inclination
Detection Method
Radial Velocity
Mass Meas. Method
Radial Velocity
Radius Meas. Method
Theoretical
Primary transit
Secondary transit
λ
Impact Parameter b
Time Vr=0
Velocity Semiamplitude K
Calculated temperature
Measured temperature
Hottest point longitude
Geometric albedo
0.5
Surface gravity log(g/gH)
Alternate Names
Data Source Type Result Value Result Figure Notes Reference
Molecule Data Source Type Result Value Result Figure Notes Reference
CO
Measurements Detected 2013 - BROGI M.
H2O
Measurements Detected 2017 - BIRKBY J.
Measurements Detected 2013 - BROGI M.

06 Apr 2015: Based on the detection of a planet to star reflected flux ratio of 6.0 ± 0.4 x 10-5 and assumed radius 1.9 RJup, Martins et al. 2015 find a planet albedo of 0.5.
19 Oct 2010: Simpson et al. (2010) infer the orbital inclination from the parent star rotation, deriving a planet mass 0.5+0.2-0.1MJ; but the coplanarity of stellar equator with planet orbits is generally not demonstrated.

  • The orbital distance to the star (0.05 AU) was incompatible with theoretical predictions (A. Boss, Science, 287, 360, 1995) and has triggered speculations on orbital migration (Lin et al. 1996, Rasio et al., 1996)
  • No second companion found (Marcy 1996)
  • Further evidence for a planet (Hatzes et al., 1996, 1997): nonradial oscillation modes (l > 4) excluded to explain RV amplitude
  • Further evidence for a planet (Pravdo et al., 1996) from X-ray non detection
  • Planet or M2 star? This question was implicitely raised by a paper by the PTI team claiming that the 51 Peg system may be resolved. See the comment by G. Marcy
  • Circumstellar disk searched for at UKIRT and KECK but not found (Trilling et al. 1999 and 2000)

Star

Roberts et al. (2011) reported a visual companion at a projected separation of 2.87 arcseconds, about 44-45 AUs. Kervella et al. (2019) estimate a mass of m ≈ 70-40+70 MJup, compatible with an early T-type brown dwarf. The visual companion may be gravitationally bound to 51 Peg, although further characterization is needed to confirm this.

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