Astronomy:HD 38858
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 48m 34.93996s[1] |
| Declination | −04° 05′ 40.7153″[1] |
| Apparent magnitude (V) | +5.97[2] |
| Characteristics | |
| Spectral type | G4V[3] |
| U−B color index | +0.10[2] |
| B−V color index | +0.64[2] |
| Astrometry | |
| Radial velocity (Rv) | +31.2[4] km/s |
| Proper motion (μ) | RA: 60.84 ± 0.41[1] mas/yr Dec.: –228.35 ± 0.33[1] mas/yr |
| Parallax (π) | 65.89 ± 0.41[1] mas |
| Distance | 49.5 ± 0.3 ly (15.18 ± 0.09 pc) |
| Details | |
| Mass | 0.886[5] M☉ |
| Radius | 0.9331 ± 0.0162[5] R☉ |
| Luminosity | 0.7943 ± 0.0101[5] L☉ |
| Surface gravity (log g) | 4.36 ± 0.06[3] cgs |
| Temperature | 5,660 ± 20[3] K |
| Metallicity [Fe/H] | –0.27 ± 0.03[3] dex |
| Rotational velocity (v sin i) | 2.61[6] km/s |
| Age | 6.2[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| Extrasolar Planets Encyclopaedia | data |
HD 38858 is a G-type star,[3] much like The Sun, with one detected planet. The planet, designated HD 38858 b, is about twice the mass of Uranus and orbits in the star's habitable zone.[8]
The last observation of this system for a dust disc or comet belt was in 2009 by the Spitzer Space Telescope; a belt was inferred at 102 AU.[7] It has an inclination of 48◦.[9]
The star exhibit a magnetic activity cycle remarkably similar to that of Sun, with the period of 10.8 years.[10]
Planetary system
The exoplanet HD 38858 b was discovered in 2011 in orbit in its host star's habitable zone, a zone in which Earth-like conditions (namely the presence of liquid water) on a planet's surface are possible.[11][12] The planet is likely a gas giant, a type of planet which astronomers believe is unlikely to support life as it is currently understood. However, the planet could have a rocky natural satellite capable of sustaining an Earth-like environment.[13] In 2020, the issue of habitability was explored by the popular YouTube channel "Fire of Learning", in which the planet was referred to as "Kynigos", and its hypothetical satellite was compared to the Jovian Moons of Europa and Io. Potential obstacles to habitability of any natural satellite, including the eccentricity of the planet's orbit, likelihood of the moon being tidally locked, and probable prevalence of geothermic activity owed to its orbit around the gas giant, were highlighted.[14][15][16]
The existence of this planet was disputed since 2015 though, attributing the planetary signal to the frequency-domain alias of the star magnetic activity cycle, although the existence of another planet on the 198-day orbit is suspected.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (disputed[10]) | 32[18] M⊕ | 1.0376 ± 0.0189 | 407.15 ± 4.2857 | 0.27 ± 0.17 | — | — |
| Disk | 102–102 AU | — | — | |||
References
- ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. Vizier catalog entry
- ↑ 2.0 2.1 2.2 Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory 4 (99): 99. Bibcode: 1966CoLPL...4...99J.
- ↑ 3.0 3.1 3.2 3.3 3.4 J. Maldonado; C. Eiroa; E. Villaver; B. Montesinos; A. Mora (2012). "Metallicity of solar-type stars with debris discs and planets". Astronomy & Astrophysics 541: A40. doi:10.1051/0004-6361/201218800. Bibcode: 2012A&A...541A..40M.
- ↑ Nordström, B. et al. (May 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs". Astronomy and Astrophysics 418 (3): 989–1019. doi:10.1051/0004-6361:20035959. Bibcode: 2004A&A...418..989N.
- ↑ 5.0 5.1 5.2 Boyajian, Tabetha S. et al. (July 2013), "Stellar Diameters and Temperatures. III. Main-sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations", The Astrophysical Journal 771 (1): 40, doi:10.1088/0004-637X/771/1/40, Bibcode: 2013ApJ...771...40B.
- ↑ Martínez-Arnáiz, R. et al. (September 2010). "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter". Astronomy and Astrophysics 520: A79. doi:10.1051/0004-6361/200913725. Bibcode: 2010A&A...520A..79M. http://eprints.ucm.es/37826/1/davidmontes17libre.pdf. Retrieved 2018-11-04.
- ↑ 7.0 7.1 Wyatt, M. C. et al. (2012). "Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems". Monthly Notices of the Royal Astronomical Society 424 (2): 1206. doi:10.1111/j.1365-2966.2012.21298.x. Bibcode: 2012MNRAS.424.1206W. citing Lawler et al. 2009, and recalculating its distance.
- ↑ LTT 2380 -- High proper-motion Star, SIMBAD Astronomical Database, accessed 11 October 2012.
- ↑ Bryden et al., promised in John E. Krist; Karl R. Stapelfeldt; Geoffrey Bryden; Peter Plavchan (2012), "Hubble Space Telescope Observations of the HD 202628 Debris Disk", Astronomical Journal 144 (2): 45, doi:10.1088/0004-6256/144/2/45, Bibcode: 2012AJ....144...45K
- ↑ 10.0 10.1 10.2 Flores, M.; González, J. F.; Jaque Arancibia, M.; Saffe, C.; Buccino, A.; López, F. M.; Ibañez Bustos, R. V.; Miquelarena, P. (2018), "HD 38858: A solar-type star with an activity cycle of ~10.8 yr", Astronomy & Astrophysics 620: A34, doi:10.1051/0004-6361/201833330
- ↑ "The Extrasolar Planet Encyclopaedia — HD 38858 b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/hd_38858_b--952/.
- ↑ Cain, Fraser (2015-06-29). "What is the Habitable Zone?" (in en-US). https://www.universetoday.com/120982/what-is-the-habitable-zone/.
- ↑ "Should We Look For Life on Gas-Giants?" (in en). https://futurism.com/life-on-gas-giants.
- ↑ "HD 38858". https://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=HD+38858.
- ↑ "Io's Alien Volcanoes | Science Mission Directorate". https://science.nasa.gov/science-news/science-at-nasa/1999/ast04oct99_1/.
- ↑ March 2018, Elizabeth Howell 22 (22 March 2018). "Europa: Facts About Jupiter's Icy Moon and Its Ocean" (in en). https://www.space.com/15498-europa-sdcmp.html.
- ↑ "hd_38858_b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/hd_38858_b--952/.
- ↑ Wyatt; m sin i is 0.0961 ± 0.012 MJ / 30.55 ± 4.11 (which Wyatt knew from most current cited paper Mayor, "HARPS XXXIV", 2011). Wyatt has likely factored in the inclination but did not state this outright in the arXiv version of the paper.
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