Notes for 51 Peg

by Jean Schneider

update: 7 October 2002

---

The planet(s):

• Detection method: Radial Velocity
  (with the Elodie spectrograph at the Observatoire de Haute Provence)
• Basic data:

  Name:	51 Peg b
  M.sini:	0.44 MJ
  Semi-major axis:	0.0512 AU
  Orbital period:	4.23 d.
  Eccentricity:	0.013
  Omega (deg):	31
  T_peri (JD-2450000):	68.89
  Inclinaison:	-

• Remarks:
  • 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)

• Data:
  • Inclination:
    • Near 90 ^o from Vsini (P. François et al. 1996).
    • < 85 ^o from absence of occultations by the companion (Henry et al. 1997)
    • ~ 0^o if it is an M2 star.
  • Radius: 1.2 - 1.4 R_J from models by Guillot et al. (1996) (depending on the mass and thus on the inclination)
  • T_eff: 1241 K (from Guillot et al. (1996));
    if the radius of the star is 1.7 R_Sun, then T_eff = 1425 K.
  • Epoch: T_o = 2450203.947 +/- 0.03 (from Butler & Marcy 1996)

• References:
  • BROWN T., KOTAK R., HORNER S., KENELLY E., KORZENNIK S., NISENSON P. & NOYES R., 1997
    A search for line shape and variations in 51 Pegasi and tau Boötis.
    ApJ. Lett., in press
    preprint
  • G. BRYDEN & D.N.C. LIN 1996
    Orbital Migration of Giant Protoplanets
    Stony Brook Workshop on Planets in Binary Stars (16-18 June 96)
    ( abstract).
  • BUNDY & MARCY G., 2000
    Search For Transit Effects in Spectra of 51 Peg and HD 209458.
    PASP, accepted.
    preprint
  • BUTLER P. & MARCY G., 1996
    The Lick Observatory Planet Search
    Submitted to: Astronomical and Biochemical Origins and the Search for Life in the Universe, IAU Colloquium No. 161, Capri 1-5 July 1996, eds. C.B. Cosmovici, S. Bowyer, and D. Werthimer
    preprint
  • COUSTENIS A., SCHNEIDER J., WITTEMBERG R., CHASSEFIERE E., GREENE T., PENNY A. & GUILLOT T., 1997
    High-resolution Ground-based Spectroscopy of 51 Peg B: Search for Atmospheric Signatures
    in Brown Dwarfs and Extrasolar Planets (Tenerife 1997) abstract
  • COUSTENIS A., SCHNEIDER J., BOCKELEE-MORVAN D., RAUER H., WITTEMBERG R., CHASSEFIERE E., GREENE T., PENNY A. & GUILLOT T., 1996
    Spectroscopy of 51 Peg B: Search for Atmospheric Signatures
    Planets Beyond the Solar System and the Next Generation of Space Missions
    Baltimore 16-18 Octonber 1996
    abstract
  • FRANCOIS P.,BRIOT D., SPITE F. & SCHNEIDER J., 1999
    Planets around 51 Peg and ups. And.
    A. & A., 349, 220
    paper
  • P.FRANCOIS, M.SPITE, D.GILLET, J.-F.GONZALEZ and F.SPITE, 1996
    Accurate determination of the projected rotational velocity of 51 Pegasi
    Astron. & Astrophys., 310, L13
    abstract.
  • GIMENEZ A., 2000
    ubvy Photometry of stars with planets.
    Astron. & Astrophys., 356, 213.
    paper
  • GLANZ J., 1997
    Is First Extrasolar Planet a Lost World?
    Science, 275, 1257
    abstract and paper
  • GLANZ J., 1997
    51 Peg and the Perils of Planet Searches
    Science, 276, 1338
    abstract and paper
  • GOUKENLEUQUE C., BEZARD B., JOGUET B., LELLOUCH E. & FREEDMAN R., 2000
    Radiative equilibrium model of 51 Peg
    Icarus, 143, 308
    paper
  • GOUKENLEUQUE C., BEZARD B. & LELLOUCH E., 1998
    Radiative Equilibrium Model of 51 Peg b
    in 30^th DPS Meeting
    abstract
  • GRAY D. & HATZES A. 1997
    Non-radial oscillation in the solar-temperature star 51 Pegasi.
    Ap.J. accepted
    preprint
  • GRAY D., 1998
    A planetary companion for 51 Pegasi implied by absence of pulsations in the stellar spectra.
    Nature, 391, 153
    abstract
  • GRAY D., 1997
    Absence of a planetary signature in the spectra of 51 Pegasi.
    Nature, 385, 795
    abstract
  • GREENHILL L., 2002
    epsilon ERIDANI, upsilon ANDROMEDAE, 51 PEGASI, HD 209458, HD 196050.
    IAU Circular, No. 7985
    full text
  • GUILLOT T., BURROWS A., HUBBARD W. B., LUNINE J. I., SAUMON, D., 1996 Giant Planets at Small Orbital Distances (model of 51 Peg b)
    ApJ. Letters, 459, L35
    (paper)
  • HATZES A., COCHRAN W. & BAKKER E., 1998
    Further evidence for the planet around 51 Pegasi
    Nature, 391, 154
    abstract and preprint
  • HATZES A., COCHRAN W. & JOHNS-KRULL C., 1996
    A Search for Variability in the Spectral Line Shapes of 51 Peg: Further Evidence for a Planet.
    ApJ. Letters in press
    abstract and preprint
  • HENRY G., BALIUNAS S., DONAHUE R., SOON W., & SAAR S., 1997
    Properties of Sun-Like Stars with Planets 51 Pegasi, 47 Ursae Majoris, 70 Virginis, and HD114762
    Apj., 474, 503
    paper
  • HORNER S., BROWN T., KENELLY E., NOYES R., JHA S., KORZENNIK S. & NISENSON P., 1997
    51 Pegasi and Tau Bootis: Planets or Pulsations?
    Poster at the Los Alamos Conference on Stellar Pulsation, June 16-20
  • KRISCIUNAS K., 1997
    The Discovery of Non-Radial Gravity-mode Pulsations in $\gamma$ Doradus-Type Stars
    Presented at IAU Symposium 185, New Eyes to See Inside the Sun and Stars. Pushing the Limits of Helio- and Asteroseismology with New Observations from Ground and from Space, Kyoto, 18-22 August, 1997
    abstract and preprint
  • LIN D. N. C., BODENHEIMER P. & RICHARDSON, D. C, 1996
    Orbital migration of the planetary companion of 51 Pegasi to its present location
    Nature, 380, 606
    paper
  • MARCY G., 1998
    Extrasolar Planets
    Nature, 391, 127
    abstract
  • MARCY G., BUTLER P., WILLIAMS E., BILDSTEN L. & GRAHAM J., 1996
    The Planet Orbiting 51 Peg
    Astrophys. J. 481, 926
    paper
  • MAYOR M. and QUELOZ D., 1995
    A Jupiter-mass companion to a solar-type star
    Nature, 378, 355
  • PAN X., SULKARNI S. COLAVITA M. & SHAO M., 1997
    Recent measurements of stars with planets using the Palomar Testbed Interferometer
    in Brown Dwarfs and Extrasolar Planets (Tenerife 1997)
    paper
  • PRAVDO S.H., ANGELI L, DRAKE S,, STERN R. & WHITE N., 1996
    The X-ray Evidence that the 51 Peg Companion is a Planet
    New Astronomy, 1, no. 2, November, p. 171
    paper
  • F. RASIO, C. TOUT, S. LUBOW and M. LIVIO 1996
    Tidal Decay of Close Planetary Orbits
    ApJ, 470, 1187
    ( preprint).
  • RAUER H., BOCKELEE-MORVAN D., COUSTENIS A., GUILLOT T. & SCHNEIDER J., 1999
    Search for an exosphere around 51 Peg with ISO.
    Astron. Astrophys., accepted
  • RUZMAIKINA T., 1999
    Formation of 51 Pegasi-Type Systems.
    Icarus submitted
  • RUZMAIKINA T., 1996
    Formation of 51 Pegasi-Type Systems
    28^th DPS meeting
    abstract
  • RYAN S, 2000
    The Host Stars of Extrasolar Planets Have Normal Lithium Abundances.
    MNRAS, in press preprint
  • TAKEDA Y., SATO B., KAMBE E., AOKI W., HONDA S., KAWANOMOTO S., MASUDA S., IZUMIURA H., WATANABE E., KOYANO H., MAEHARA H., NORIMOTO Y., OKADA T., SHIMIZU Y., URAGUCHI F., YANAGIZAWA K. YOSHIDA M., NIYAMA S. & ANDO H., 2001
    Photospheric Abundances of Volatile and Refractory Elements in Planet-Harboring Stars.
    PASJ, 53, 1211
    paper
  • TRILLING D., BROWN R. & RIVKIN A., 1999
    Circumstellar dust disks and extrasolar planets: Far-off analogs of our Solar System
    in 31^st Annual Meeting of the DPS
    abstract
  • TRILLING D., BROWN R. & RIVKIN A., 2000
    Circumstellar Dust Disks around Stars with Known Planetary Companions.
    ApJ., 529, 499
    paper
  • WALKER G., 1997
    One of our planets is missing
    Nature, 385, 775
    abstract
  • ZHAO G., CHEN Y., QIU H. & LI. Z., 2002
    Chemical Abundances of 15 Extrasolar-Planet Host Stars.
    Astron. J., 124, 2224
    paper

• Other Web pages:
  1. Geneva Observatory data
  2. Velocity curve and data (Butler and Marcy)
  3. Precise radial velocity with AFOE (Advanced Fiber Optic Echelle Spectrometer; Sylvain G. Korzennik et al., Harvard)
  4. David Gray's comments.
  5. photometric monitoring of 51 Peg at Mount Wilson (Henry et al.) versus orbital phase and Julian Date
  6. 51 Peg Web page at U. of Oregon.
  7. Illustration From Adler Planetarium: Illustration of our solar system compared to 51 Peg and animations.
  8. Visualisation of 51 Peg (John Whatmough)
  9. Sky chart (Seti League)
  10. Vanishing World (Scientific American)

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The star:

• Distance: 14.7 pc
• Spectral type: G2IV
• Metallicity: [Fe/H] = 0.06 - 0.19
• Apparent magnitude: B = 6.16, V = 5.5
• Coordinates (2000): RA = 22 57 27.14, DEC = +20 46 04.5
• More data:
  • Basic Data (from simbad )
  • Most recent refs. (from ADS; enter `51 Peg' in the `objects' field)

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