HD 73256

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HD 73256
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Pyxis
Right ascension 08h 36m 23.01654s [1]
Declination −30° 02 15.4462 [1]
Apparent magnitude  (V)8.08 [2]
Characteristics
Spectral type G8 IV-V Fe+0.5 [3]
B−V color index 0.782±0.002 [2]
Variable type BY Dra [4]
Astrometry
Radial velocity (Rv)29.66±0.14 [1]  km/s
Proper motion (μ)RA: −182.193(17)  mas/yr [1]
Dec.: 67.373(21)  mas/yr [1]
Parallax (π)27.2441 ± 0.0217  mas [1]
Distance 119.72 ± 0.10  ly
(36.71 ± 0.03  pc)
Absolute magnitude  (MV)5.20 [2]
Details [5]
Mass 1.01±0.03  M
Radius 0.94±0.02  R
Luminosity 0.74±0.01  L
Surface gravity (log g)4.49±0.03  cgs
Temperature 5,532±36  K
Metallicity [Fe/H]0.29±0.05 [6]   dex
Rotational velocity (v sin i)3.22±0.32 [6]  km/s
Age 2.5±2.3  Gyr
Other designations
CS Pyx, CD−29°6456, HD  73256, HIP  42214, SAO  176159 [7]
Database references
SIMBAD data

HD 73256 is a variable star in the southern constellation of Pyxis. It has the variable star designation CS Pyxidis. With a baseline apparent visual magnitude of 8.08, [2] it requires binoculars or a small telescope to view. The star is located at a distance of 120  light years from the Sun based on parallax, [1] and is drifting further away with a radial velocity of +30 km/s. [2]

Contents

The stellar classification of this star is G8IV-VFe+0.5, which suggests a slightly evolved G-type main-sequence star with a mild overabundance of iron in the spectrum. It is a BY Draconis variable with a period of 13.97 days, showing a variation of 0.03 in magnitude due to chromospheric activity. [4] The star appears overluminous for its class, which may be the result of a high metallicity. [6] The star has roughly the same mass and a slightly smaller radius as the Sun, but is radiating 74% of the Sun's luminosity. [5] It is around 2–3 billion years old and is spinning with a projected rotational velocity of 3.2 km/s. [6]

Planetary system

In 2003, S. Udry and colleagues reported the discovery of a planet in orbit around HD 73256 using data from the CORALIE spectrograph. This object is a hot Jupiter with at least 1.87 times the mass of Jupiter in an orbit with a period of 2.55 days. [6] Assuming the planet is perfectly grey with no greenhouse or tidal effects, and a Bond albedo of 0.1, the temperature would be about 1300 K. This is close to 51 Pegasi b; between the predicted temperatures of HD 189733 b and HD 209458 b (1180-1392K), before they were measured. It is a candidate for "near-infrared characterisation with the VLTI Spectro-Imager". [8]

In 2018, K. Ment and colleagues reported an attempt to confirm the existence of this planet using Keck/HIRES data, but were unable to do so despite a likelihood of success. Thus the existence of this object is disputed. [9]

In 2023, a different substellar companion on a wide orbit, likely a brown dwarf, was discovered using both radial velocity and astrometry. This study did also detect HD 73256 b, but did not update its parameters or address the dispute. [10]

The HD 73256 planetary system [6] [10]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b(disputed)>1.87 ± 0.49 MJ 0.0372.54858 ± 0.000160.029 ± 0.02
c16±1  MJ 3.8±0.12690+60
−102
0.16±0.0729+5
−3
or 152+8
−7
°

See also

Related Research Articles

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<span class="mw-page-title-main">HD 80606 and HD 80607</span> Binary star system in the constellation Ursa Major

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<span class="mw-page-title-main">HD 179949 b</span> Extrasolar planet that orbits the star HD 179949

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<span class="mw-page-title-main">HD 15082</span> Star in the constellation Andromeda

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<span class="mw-page-title-main">Sigma Ophiuchi</span> Star in the constellation Ophiuchus

Sigma Ophiuchi, Latinized from σ Ophiuchi, is a single, orange-hued star in the equatorial constellation Ophiuchus. Its apparent visual magnitude is 4.31, which is bright enough to be faintly visible to the naked eye. The annual parallax shift of 3.62 mas as seen from Earth provides a distance estimate of roughly 900 light years. It is moving closer to the Sun with a radial velocity of −28 km/s.

References

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  5. 1 2 Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv: 1411.4302 . Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID   54555839.
  6. 1 2 3 4 5 6 Udry, S.; et al. (2003). "The CORALIE survey for southern extra-solar planets X. A Hot Jupiter orbiting HD 73256". Astronomy and Astrophysics. 407 (2): 679–684. arXiv: astro-ph/0304248 . Bibcode:2003A&A...407..679U. doi:10.1051/0004-6361:20030815. S2CID   118889984.
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  8. Renard, Stéphanie; Absil, Olivier; Berger, Jean-Philippe; Bonfils, Xavier; Forveille, Thierry; Malbet, Fabien (2008). "Prospects for near-infrared characterisation of hot Jupiters with the VLTI Spectro-Imager (VSI)" (PDF). Proceedings of SPIE. Optical and Infrared Interferometry. 7013: 70132Z–70132Z–10. arXiv: 0807.3014 . Bibcode:2008SPIE.7013E..2ZR. doi:10.1117/12.790494. S2CID   119268109.
  9. Ment, Kristo; et al. (November 2018). "Radial Velocities from the N2K Project: Six New Cold Gas Giant Planets Orbiting HD 55696, HD 98736, HD 148164, HD 203473, and HD 211810". The Astronomical Journal. 156 (5): 45. arXiv: 1809.01228 . Bibcode:2018AJ....156..213M. doi: 10.3847/1538-3881/aae1f5 . S2CID   119243619. 213.
  10. 1 2 Philipot, F.; Lagrange, A.-M.; et al. (August 2023). "Multi techniques approach to identify and/or constrain radial velocity sub-stellar companions". Astronomy & Astrophysics . arXiv: 2308.05417 . doi:10.1051/0004-6361/202346612. S2CID   260775968.