Astronomy:HD 28185

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Short description: Star in the constellation Eridanus
HD 28185
Observation data
Equinox J2000.0]] (ICRS)
Constellation Eridanus
Right ascension  04h 26m 26.323s[1]
Declination −10° 33′ 02.95″[1]
Apparent magnitude (V) +7.80[2]
Characteristics
Evolutionary stage Main sequence/subdwarf
Spectral type G6.5IV-V[3]
B−V color index 0.750±0.010[2]
Astrometry
Radial velocity (Rv)50.40±0.14[1] km/s
Proper motion (μ) RA: 84.070±0.018[1] mas/yr
Dec.: −59.637±0.016[1] mas/yr
Parallax (π)25.4868 ± 0.0207[1] mas
Distance128.0 ± 0.1 ly
(39.24 ± 0.03 pc)
Absolute magnitude (MV)4.67[2]
Details
Mass1.0±0.1[4] M☉
Radius1.15±0.03[4] R☉
Luminosity1.18±0.01[4] L☉
Surface gravity (log g)4.33±0.03[4] cgs
Temperature5,609±41[4] K
Metallicity [Fe/H]0.19±0.01[2] dex
Rotation30 days[citation needed]
Age4.8±4.4[4] Gyr
Other designations
BD–10°919, HD 28185, HIP 20723, SAO 149631, GSC 05317-00733[5]
Database references
SIMBADdata
Extrasolar Planets
Encyclopaedia		data

HD 28185 is a yellow dwarf star similar to the Sun located 128 light-years away from Earth in the constellation Eridanus. The designation HD 28185 refers to its entry in the Henry Draper catalogue. The star is known to possess one long-period extrasolar planet.

Characteristics

According to measurements from the Gaia spacecraft, HD 28185 has a parallax of 25.4868 milliarcseconds,[1] which corresponds to a distance of 39.24 parsecs (128.0 light-years). Since the star is located further than 25 parsecs from Earth, it is not listed in the Gliese Catalogue of Nearby Stars. With an apparent magnitude of 7.81, the star is almost never visible with the naked eye, though it can be seen using binoculars.

HD 28185 is similar to the Sun in terms of mass, radius, and luminosity. The star is on the main sequence and is generating energy by fusing hydrogen in its core.[citation needed] The spectral type of G6.5IV-V implies HD 28185 is cooler than the Sun. Like the majority of extrasolar planet host stars, HD 28185 is metal-rich relative to the Sun, containing around 173% of the solar abundance of iron. The star rotates slower than the Sun, with a period of around 30 days, compared to 25.4 days for the Sun.

Based on the star's chromospheric activity, HD 28185 is estimated to have an age of around 2,900 million years. On the other hand, evolutionary models give an age of around 7,500 million years and a mass 0.99 times that of the Sun.[6] The higher luminosity and longer rotation period favour an older age for the star.

Planetary system

In 2001 an extrasolar planet similar in size to Jupiter designated HD 28185 b was discovered in orbit around the star with a period of 1.04 years.[6][7] Unlike many long-period extrasolar planets, it has a low orbital eccentricity.[8] The planet experiences similar insolation to Earth, which has led to speculations about the possibilities for habitable moons.[9][10] In addition, numerical simulations suggest that low-mass planets located in the gas giant's Trojan points would be stable for long periods.[11] The planet's existence was independently confirmed by the Magellan Planet Search Program in 2008.[12]

The star also shows evidence of a long-term radial velocity trend, which may indicate the presence of an additional outer companion.[13] In 2022, the presence of an outer companion, likely a brown dwarf, was confirmed using a combination of radial velocity and astrometry.[14]

The HD 28185 planetary system[14]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
b ≥5.837+0.486
−0.510 MJ 		1.035+0.042
−0.046 		1.056+0.0001
−0.0002 		0.055+0.004
−0.003 		— —
c 19.639+2.266
−2.137 MJ 		13.176+0.518
−0.689 		47.688+0.802
−1.841 		0.120+0.021
−0.022 		57.650+8.146
−5.747° 		—

See also

References

  1. ↑ 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. ↑ 2.0 2.1 2.2 2.3 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. 
  3. ↑ Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (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. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 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. 
  5. ↑ "HD 28185". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+28185. 
  6. ↑ 6.0 6.1 Santos, N. (2001). "The CORALIE survey for southern extra-solar planets VI. New long-period giant planets around HD 28185 and HD 213240". Astronomy and Astrophysics 379 (3): 999–1004. doi:10.1051/0004-6361:20011366. Bibcode: 2001A&A...379..999S. 
  7. ↑ "Exoplanets: The Hunt Continues!" (Press release). Garching, Germany: European Southern Observatory. April 4, 2001. Retrieved December 27, 2012.
  8. ↑ Butler, R. P. et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. doi:10.1086/504701. Bibcode: 2006ApJ...646..505B. 
  9. ↑ Mullen, L. (2001). "Extrasolar Planets with Earth-like Orbits". http://nai.nasa.gov/news_stories/news_detail.cfm?ID=126. 
  10. ↑ Jones, Barrie W.; Sleep, P. Nick; Underwood, David R. (2006). "Habitability of Known Exoplanetary Systems Based on Measured Stellar Properties". The Astrophysical Journal 649 (2): 1010–1019. doi:10.1086/506557. Bibcode: 2006ApJ...649.1010J. 
  11. ↑ Schwarz, R.; Dvorak, R.; Süli, Á.; Érdi, B. (2007). "Survey of the stability region of hypothetical habitable Trojan planets". Astronomy and Astrophysics 474 (3): 1023–1029. doi:10.1051/0004-6361:20077994. Bibcode: 2007A&A...474.1023S. 
  12. ↑ Minniti, Dante et al. (2009). "Low-Mass Companions for Five Solar-Type Stars From the Magellan Planet Search Program". The Astrophysical Journal 693 (2): 1424–1430. doi:10.1088/0004-637X/693/2/1424. Bibcode: 2009ApJ...693.1424M. 
  13. ↑ Chauvin, G.; Lagrange, A.-M.; Udry, S.; Fusco, T.; Galland, F.; Naef, D.; Beuzit, J.-L.; Mayor, M. (2006). "Probing long-period companions to planetary hosts. VLT and CFHT near infrared coronographic imaging surveys". Astronomy and Astrophysics 456 (3): 1165–1172. doi:10.1051/0004-6361:20054709. Bibcode: 2006A&A...456.1165C. 
  14. ↑ 14.0 14.1 Feng, Fabo et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series 262 (21): 21. doi:10.3847/1538-4365/ac7e57. Bibcode: 2022ApJS..262...21F. 

External links

Coordinates: Sky map 04h 26m 26.3205s, −10° 33′ 02.955″



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