Astronomy:HD 73256
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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)[1] mas/yr Dec.: 67.373(21)[1] mas/yr |
| Parallax (π) | 27.2441 ± 0.0217[1] mas |
| 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 | |
| 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]
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]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (disputed) | >1.87 ± 0.49 MJ | 0.037 | 2.54858 ± 0.00016 | 0.029 ± 0.02 | — | — |
| c | 16±1 MJ | 3.8±0.1 | 2690+60 −102 |
0.16±0.07 | 29+5 −3 or 152+8 −7° |
— |
See also
- HD 72659
- List of extrasolar planets
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ Gray, R. O. et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal 132 (1): 161–170. doi:10.1086/504637. Bibcode: 2006AJ....132..161G.
- ↑ 4.0 4.1 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ 5.0 5.1 Bonfanti, A. et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics 575: A18. doi:10.1051/0004-6361/201424951. Bibcode: 2015A&A...575A..18B. http://www.aanda.org/articles/aa/full_html/2015/03/aa24951-14/aa24951-14.html.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 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. doi:10.1051/0004-6361:20030815. Bibcode: 2003A&A...407..679U. http://www.aanda.org/articles/aa/full/2003/32/aa3857/aa3857.html.
- ↑ "HD 73256". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+73256.
- ↑ 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)". Proceedings of SPIE. Optical and Infrared Interferometry 7013: 70132Z–70132Z–10. doi:10.1117/12.790494. Bibcode: 2008SPIE.7013E..2ZR. http://orbi.ulg.ac.be/bitstream/2268/30158/1/SPIE_poster.pdf.
- ↑ 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. doi:10.3847/1538-3881/aae1f5. 213. Bibcode: 2018AJ....156..213M.
- ↑ 10.0 10.1 Philipot, F. et al. (August 2023). "Multi techniques approach to identify and/or constrain radial velocity sub-stellar companions". Astronomy & Astrophysics. doi:10.1051/0004-6361/202346612.
Coordinates: 
08h 36m 23.0163s, −30° 02′ 15.442″
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