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  HD 41004Ab: a planet in a multiple system

Last update: July the 1st 2003
 
 
 
 
 
  • Announced during the XIX th IAP Colloquium "Extrasolar Planets: Today & Tormorrow", Paris, June 2003

  • A Hierarchic quadruple system: A 2.3 M_Jup planet orbiting a K2V star + a 19 M_Jup brown dwarf orbiting a M4V star
  • HD 41004 is a close visual binary (K2V star + M4V star; separation: 0.5 arcsec).

  • A 1.3-day radial-velocity signal was rapidly detected

  • Santos et al. 2002 (A&A 392, 215) have interpreted this signal as the result of the presence of a brown dwarf orbiting the secondary star HD 41004 B

  • Zucker et al. 2003 (A&A 404, 775) have detected the secondary spectrum using TODCOR (Zucker & Mazeh 1994, ApJ 420, 806), a 2-D correlation algorithm. The radial-velocity variation of the secondary spectrum has a period of 1.3 d, validating the interpretation by Santos et al.

  • Zucker et al. 2004 (A&A 426, 695) have finally detected a longer-period velocity variation of the primary spectrum (see the Figure below). This variation is due to the presence of a planet around the primary star

    • HD 41004 A temporal velocities obtained with TODOCOR
    from CORALIE spectra
    Larger image (395 kb)


  • Orbital solution (from Zucker et al. 2004):

    Object
    Period
    (days)
    T0
    (JD - 2 400 000)
    Eccentricity
    V
    (km/s)
    Omega
    (deg)
    K1
    (km/s)
    m2sini
    (M_Jup)
    a
    (AU)
    N
    Residuals
    (m/s)
    HD 41004 Ab
    924 +/- 25
    52455 +/- 26
    0.5 (fixed)
    42.5265 +/- 0.0049
    71.7 +/- 4.6
    0.0645 +/- 0.0027
    2.436 +/- 0.098
    1.64
    149
    10.0
    HD 41004 Bb
    1.328300 +/- 0.000012
    52434.880 +/- 0.029
    0.081 +/- 0.012
    -
    178.5 +/- 7.8
    6.114 +/- 0.071
    18.37 +/- 0.22
    0.02
    "
    "


  • Stellar properties:

    Parameter
    Value
    Reference
    Sp. Type
    K1V/K2V
    Hipparcos
    pi (mas)
    23.24
    Hipparcos
    d (pc)
    43
    Hipparcos
    m_v (mag)
    8.65
    Hipparcos
    B-V (mag)
    0.887
    Hipparcos
    T_eff (K)
    5010
    Santos et al. 2002
    M_v (mag)
    5.48
    -
    L (L_sol)
    0.65
    -
    log(g) (CGS)
    4.42
    Santos et al. 2002
    M_1 (M_sol)
    0.7
    Santos et al. 2002
    log(R'HK)
    -4.66
    Santos et al. 2002
    P_rot (d)
    27
    Santos et al. 2002
    Vsini (km/s)
    1.22
    Santos et al. 2002
    Age (Gyr)
    1.6
    Santos et al. 2002
    [Fe/H]
    -0.09/+0.10
    Santos et al. 2002

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    stephane.udry@obs.unige.ch