View source for HD 38858

{{Short description|Star in the constellation Orion}}
{{Starbox begin 
| name = HD 38858
}} 
{{Starbox observe 
| epoch = J2000.0
| constell = Orion
| ra = {{RA|05|48|34.93996}}<ref name="van Leeuwen2007"/>
| dec = {{DEC|-04|05|40.7153}}<ref name="van Leeuwen2007"/>
| appmag_v = +5.97<ref name="clpl4"/>
}}
{{Starbox character
| class = G4V<ref name="metal"/>
| b-v=+0.64<ref name="clpl4"/>
| u-b=+0.10<ref name="clpl4"/>
| variable=
}}
{{Starbox astrometry 
| radial_v = +31.2<ref name="Nordstrom2004"/>
| prop_mo_ra = {{nowrap|60.84 ± 0.41}}<ref name="van Leeuwen2007"/>
| prop_mo_dec = {{nowrap|–228.35 ± 0.33}}<ref name="van Leeuwen2007"/>
| parallax = 65.89
| p_error = 0.41
| parallax_footnote = <ref name="van Leeuwen2007"/>
| absmag_v = 
}}
{{Starbox detail 
| age_gyr = 6.2<ref name="disk"/>
| metal_fe = {{nowrap|–0.27 ± 0.03}}<ref name="metal"/>
| mass = 0.886<ref name="Boyajian2013"/>
| gravity = {{nowrap|4.36 ± 0.06}}<ref name="metal"/>
| temperature = {{nowrap|5,660 ± 20}}<ref name="metal"/>
| radius = {{nowrap|0.9331 ± 0.0162}}<ref name="Boyajian2013"/>
| luminosity = {{nowrap|0.7943 ± 0.0101}}<ref name="Boyajian2013"/>
| rotational_velocity=2.61<ref name=aaa520_A79/>
}}
{{Starbox catalog
| names = [[Bonner Durchmusterung|BD]]–04 1244, [[Catalogues of Fundamental Stars|FK5]] 1155, [[Gliese-Jahreiss catalogue|GJ]] 1085, [[Henry Draper Catalogue|HD]] 38858, [[Hipparcos#Published catalogues|HIP]] 27435, [[Luyten Two-Tenths catalogue|LTT]] 2380, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 132554, [[2MASS]] .
}}
{{Starbox reference
| Simbad=LTT+2380
| NSTED=HD+38858
| EPE=HD+38858
}}
{{Starbox end}}
'''HD 38858''' is a [[G-type star]],<ref name="metal">{{cite journal |author=J. Maldonado |author2=C. Eiroa |author3=E. Villaver |author4=B. Montesinos |author5=A. Mora
 |date = 2012 | journal=Astronomy & Astrophysics
 |title = Metallicity of solar-type stars with debris discs and planets
 |arxiv = 1202.5884 | doi=10.1051/0004-6361/201218800
|volume=541
|pages = A40 |bibcode = 2012A&A...541A..40M |s2cid = 46328823 }}</ref> much like [[Sun|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 [[Circumstellar habitable zone|habitable zone]].<ref>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=LTT+2380 LTT 2380 -- High proper-motion Star], SIMBAD Astronomical Database, accessed 11 October 2012.</ref>

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.<ref name="disk">{{cite journal | display-authors=1
 |last1=Wyatt |first1=M. C. |last2=Kennedy |first2=G. |last3=Sibthorpe |first3=B. |last4=Moro-Martín |first4=A. |last5=Lestrade |first5=J.-F. |last6=Ivison |first6=R. J. |last7=Matthews |first7=B. |last8=Udry |first8=S. |last9=Greaves |first9=J. S. |last10=Kalas |first10=P. |last11=Lawler |first11=S. |last12=Su |first12=K. Y. L. |last13=Rieke |first13=G. H. |last14=Booth |first14=M. |last15=Bryden |first15=G. |last16=Horner |first16=J. |last17=Kavelaars |first17=J. J. |last18=Wilner |first18=D.
 |date = 2012 | journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=424 |issue=2 |page=1206 |title = Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems
 |arxiv = 1206.2370 | doi=10.1111/j.1365-2966.2012.21298.x |doi-access=free
 |bibcode = 2012MNRAS.424.1206W 
|s2cid=54056835 }} citing Lawler ''et al.'' 2009, and recalculating its distance.</ref> It has an inclination of 48◦.<ref>Bryden ''et al.'', promised in {{citation
|journal=Astronomical Journal
|volume=144
|issue=2
|page=45
|arxiv=1206.2078
|year=2012
|title=Hubble Space Telescope Observations of the HD 202628 Debris Disk
|author1=John E. Krist |author2=Karl R. Stapelfeldt |author3=Geoffrey Bryden |author4=Peter Plavchan |bibcode = 2012AJ....144...45K |doi = 10.1088/0004-6256/144/2/45 |s2cid=40040285
}}</ref>

The star exhibit a magnetic activity cycle remarkably similar to that of Sun, with the period of 10.8 years.<ref name=Flores2018/>

==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.<ref>{{Cite encyclopedia|url=https://exoplanet.eu/catalog/hd_38858_b--952/|encyclopedia=[[Extrasolar Planets Encyclopaedia]]|title=The Extrasolar Planet Encyclopaedia — HD 38858 b|access-date=2020-03-06}}</ref><ref>{{Cite web|url=https://www.universetoday.com/120982/what-is-the-habitable-zone/|title=What is the Habitable Zone?|last=Cain|first=Fraser|date=2015-06-29|website=Universe Today|language=en-US|access-date=2020-03-06}}</ref> The planet is likely a [[gas giant]], a type of planet which [[astronomer]]s believe is unlikely to support [[life]] as it is currently understood. However, the planet could have a [[Terrestrial planet|rocky]] [[natural satellite]] capable of sustaining an Earth-like environment.<ref>{{Cite web|url=https://futurism.com/life-on-gas-giants|title=Should We Look For Life on Gas-Giants?|website=Futurism|language=en|access-date=2020-03-06}}</ref> 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 [[Moons of Jupiter|Jovian Moons]] of [[Europa (moon)|Europa]] and [[Io (moon)|Io]]. Potential obstacles to habitability of any natural satellite, including the [[Orbital eccentricity|eccentricity]] of the planet's orbit, likelihood of the moon being [[Tidal locking|tidally locked]], and probable prevalence of [[Geothermal energy|geothermic activity]] owed to its orbit around the gas giant, were highlighted.<ref>{{Cite web|url=https://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=HD+38858|title=HD 38858|website=exoplanetarchive.ipac.caltech.edu|access-date=2020-03-06}}</ref><ref>{{Cite web|url=https://science.nasa.gov/science-news/science-at-nasa/1999/ast04oct99_1/|title=Io's Alien Volcanoes {{!}} Science Mission Directorate|website=science.nasa.gov|access-date=2020-03-06}}</ref><ref>{{Cite web|url=https://www.space.com/15498-europa-sdcmp.html|title=Europa: Facts About Jupiter's Icy Moon and Its Ocean|last=March 2018|first=Elizabeth Howell 22|website=Space.com|date=22 March 2018|language=en|access-date=2020-03-06}}</ref>

The existence of this planet was disputed since 2015 though, attributing the planetary signal to the [[Aliasing|frequency-domain alias]] of the star magnetic activity cycle, although the existence of another planet on the 198-day orbit is suspected.<ref name=Flores2018/>

{{OrbitboxPlanet begin
| table_ref = <ref name="exoplaneteu">{{cite encyclopedia | url=https://exoplanet.eu/catalog/hd_38858_b--952/ | encyclopedia=[[Extrasolar Planets Encyclopaedia]] | title=hd_38858_b | date=2015 }}</ref> 
| period_unit=day
}}
{{OrbitboxPlanet hypothetical
| exoplanet = b
| semimajor = 1.0376  ± 0.0189
| eccentricity = 0.27 ± 0.17
| period = 407.15 ± 4.2857
| mass_earth = 32<ref>Wyatt; m sin i is 0.0961 ± 0.012 M<sub>J</sub> / 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.</ref>
|status=disputed<ref name=Flores2018>{{citation|arxiv=1809.05581|year=2018|title=HD 38858: A solar-type star with an activity cycle of ~10.8 yr|doi=10.1051/0004-6361/201833330|last1=Flores|first1=M.|last2=González|first2=J. F.|last3=Jaque Arancibia|first3=M.|last4=Saffe|first4=C.|last5=Buccino|first5=A.|last6=López|first6=F. M.|last7=Ibañez Bustos|first7=R. V.|last8=Miquelarena|first8=P.|journal=Astronomy & Astrophysics|volume=620|pages=A34|s2cid=126153522}}</ref>
}} 
{{OrbitboxPlanet disk
| disk= Disk
| periapsis = 102
| apoapsis = 102
}} 
{{Orbitbox end}}

==References==
{{Reflist|refs=

<ref name="van Leeuwen2007">{{cite journal
 | first=F. | last=van Leeuwen
 | title=Validation of the new Hipparcos reduction
 | journal=Astronomy and Astrophysics
 | volume=474 | issue=2 | pages=653–664
 |date=November 2007
 | bibcode=2007A&A...474..653V
 | doi=10.1051/0004-6361:20078357
 | arxiv=0708.1752
| s2cid=18759600
 }} [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=27365 Vizier catalog entry ]</ref>

<ref name="Nordstrom2004">{{cite journal
 | last1=Nordström | first1=B.
 | last2=Mayor | first2=M.
 | last3=Andersen | first3=J.
 | last4=Holmberg | first4=J.
 | last5=Pont | first5=F.
 | last6=Jørgensen | first6=B. R.
 | last7=Olsen | first7=E. H.
 | last8=Udry | first8=S.
 | last9=Mowlavi | first9=N.
 | display-authors=1
 | title=The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
 | journal=Astronomy and Astrophysics
 | volume=418 | issue=3
 | pages=989–1019
 |date=May 2004
 | arxiv=astro-ph/0405198
 | bibcode=2004A&A...418..989N
 | doi=10.1051/0004-6361:20035959
| s2cid=11027621
 }}</ref>

<ref name=aaa520_A79>{{cite journal | display-authors=1 | last1=Martínez-Arnáiz | first1=R. | last2=Maldonado | first2=J. | last3=Montes | first3=D. | last4=Eiroa | first4=C. | last5=Montesinos | first5=B. | title=Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter | journal=Astronomy and Astrophysics | volume=520 | page=A79 | date=September 2010 | doi=10.1051/0004-6361/200913725 | bibcode=2010A&A...520A..79M | arxiv=1002.4391 | s2cid=43455849 | url=http://eprints.ucm.es/37826/1/davidmontes17libre.pdf | access-date=2018-11-04 | archive-date=2017-09-22 | archive-url=https://web.archive.org/web/20170922031257/http://eprints.ucm.es/37826/1/davidmontes17libre.pdf | url-status=dead }}</ref>

<ref name="clpl4">{{cite journal | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | page=99 | date=1966 | bibcode=1966CoLPL...4...99J }}</ref>

<ref name="Boyajian2013">{{citation
 | last1 = Boyajian | first1 = Tabetha S.
 | last2 = von Braun | first2 = Kaspar
 | last3 = van Belle | first3 = Gerard
 | last4 = Farrington | first4 = Chris
 | last5 = Schaefer | first5 = Gail
 | last6 = Jones | first6 = Jeremy
 | last7 = White | first7 = Russel
 | last8 = McAlister | first8 = Harold A.
 | last9 = ten Brummelaar | first9 = Theo A.
 | last10 = Ridgway | first10 = Stephen
 | last11 = Gies | first11 = Douglas
 | last12 = Sturmann | first12 = Laszlo
 | last13 = Sturmann | first13 = Judit
 | last14 = Turner | first14 = Nils H.
 | last15 = Goldfinger | first15 = P. J.
 | last16 = Vargas | first16 = Norm
 | display-authors = 1
 | title = Stellar Diameters and Temperatures. III. Main-sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations
 | journal = The Astrophysical Journal
 | volume = 771 | issue = 1 | page = 40
 |date=July 2013
 | arxiv = 1306.2974
 | doi = 10.1088/0004-637X/771/1/40
 | bibcode = 2013ApJ...771...40B
 | s2cid = 14911430
 | postscript = .
}}</ref>

}}

{{Stars of Orion}}

[[Category:Orion (constellation)]]
[[Category:G-type main-sequence stars]]
[[Category:Hypothetical planetary systems]]
[[Category:Henry Draper Catalogue objects|038858]]
[[Category:Bright Star Catalogue objects|2007]]
[[Category:Hipparcos objects|027435]]
[[Category:Gliese and GJ objects|1085]]
[[Category:Durchmusterung objects|BD-04 1244]]
[[Category:2MASS objects|J05483495-0405404]]


{{main-star-stub}}