View source for HD 28185 b

{{Short description|Gas giant orbiting HD 28185}}
{{Infobox planet
| name                     = HD 28185 b
| image                    = Jkv.HD28185.b.png
| caption                  = An artist's impression of HD28185 b
<!-- DISCOVERY           -->
| discoverer               = Santos ''et al.''
| discovery_site           =  [[La Silla Observatory]]
| discovered               = April 4, 2001<ref name="eso0114"/>
| discovery_method         = [[Radial velocity]] ([[CORALIE]])
<!-- DESIGNATIONS        -->
<!-- ORBITAL             --> 
| orbit_ref                = <ref name="Feng2022"/>
| apsis                    = astron
| semimajor                = {{val|1.035|0.042|0.046|ul=AU}}
| eccentricity             = {{val|0.055|0.004|0.003}}
| period                   = {{convert|1.056|±|0.0002|yr|d|lk=on}}
| time_periastron          = {{val|2452262.394|3.714|3.315}}
| arg_peri                 = {{val|356.596|3.495|3.155|u=deg}}
| semi-amplitude           = {{val|163.657|0.653|0.533}}
| star                     = [[HD 28185]]
<!-- PHYS CHARS          --> 
| physical_ref             = <ref name="Feng2022"/>
| mass                     = ≥{{val|5.837|0.486|0.510|ul=Jupiter mass}}
<!-- ATMOSPHERE          --> 
<!-- NOTES               --> 
}}
'''HD 28185 b''' is an [[extrasolar planet]] 128 [[light-year]]s away from Earth in the [[constellation]] of [[Eridanus (constellation)|Eridanus]]. The planet was discovered orbiting the [[Sun-like]] [[star]] [[HD 28185]] in April 2001 as a part of the [[CORALIE]] survey for southern extrasolar planets, and its existence was independently confirmed by the [[Magellan Planet Search Survey]] in 2008.<ref>{{cite journal | title=Low-Mass Companions for Five Solar-Type Stars From the Magellan Planet Search Program | journal=[[The Astrophysical Journal]] | date=2009 | volume=693 | issue=2 | pages=1424–1430 | doi=10.1088/0004-637X/693/2/1424 | display-authors=1 | last1=Minniti | first1=Dante | last2=Butler | first2=R. Paul | last3=López-Morales | first3=Mercedes | last4=Shectman | first4=Stephen A. | last5=Adams | first5=Fred C. | last6=Arriagada | first6=Pamela | last7=Boss | first7=Alan P. | last8=Chambers | first8=John E. | bibcode=2009ApJ...693.1424M|arxiv = 0810.5348 | s2cid=119224845 }}</ref> HD 28185 b orbits its sun in a circular orbit that is at the inner edge of its star's [[habitable zone]].<ref name="jones">{{cite journal|bibcode=2006ApJ...649.1010J|author1=Jones, Barrie W. |author2=Sleep, P. Nick |author3=Underwood, David R. |title=Habitability of Known Exoplanetary Systems Based on Measured Stellar Properties|journal=[[The Astrophysical Journal]]|volume=649|issue=2|date=2006|pages=1010&ndash;1019|doi=10.1086/506557|arxiv = astro-ph/0603200 |s2cid=119078585 }}</ref>

== Discovery ==
HD 28185 b was discovered by detecting small periodic variations in the [[radial velocity]] of its parent star caused by the [[gravity|gravitational attraction]] of the planet. This was achieved by measuring the [[Doppler shift]] of the star's [[spectrum]]. In 2001 it was announced that HD 28185 exhibited a wobble along the line-of-sight with a period of 383 days, with an [[amplitude]] indicating a [[minimum mass]] 5.72 times that of [[Jupiter]].<ref name="eso0114"/><ref>{{cite journal|url=http://www.edpsciences.org/articles/aa/abs/2001/45/aah3054/aah3054.html|author=Santos, N.|display-authors=etal|title=The CORALIE survey for southern extra-solar planets VI. New long-period giant planets around HD 28185 and HD 213240|journal=[[Astronomy and Astrophysics]]|volume=379|date=2001|issue=3|pages=999&ndash;1004|doi=10.1051/0004-6361:20011366|bibcode=2001A&A...379..999S|url-status=dead|archive-url=https://web.archive.org/web/20060713024330/http://www.edpsciences.org/articles/aa/abs/2001/45/aah3054/aah3054.html|archive-date=2006-07-13|arxiv=astro-ph/0106255|s2cid=59061741 }}</ref>

== Orbit and mass ==
HD 28185 b takes 1.04 years to orbit its parent star. Unlike most known long-[[orbital period|period]] planets, the orbit of HD 28185 b has a low [[eccentricity (orbit)|eccentricity]], comparable to that of [[Mars]] in the [[Solar System]].<ref name="Butler2006"/> The orbit lies entirely within its star's habitable zone.<ref name="jones" />

The amplitude of the radial velocity oscillations means that the planet has a mass at least 5.7 times that of Jupiter in the Solar System. However, the radial velocity method only yields a minimum value on the planet's mass, depending on the orbital [[inclination]] to our [[line-of-sight propagation|line-of-sight]]. Therefore, the [[true mass]] of the planet may be much greater than this lower limit.

== Characteristics ==
Given the planet's high mass, it is most likely to be a [[gas giant]] with no solid surface. Since the planet has only been detected indirectly through observations of the star, properties such as its [[radius]], composition, and [[temperature]] are unknown. Periastron (0.959 AU), semimajor axis (1.031 AU) and apastron (1.102 AU)  irradiances are 112%, 96.6% and 84.5% that of the Earth.  <ref group="note">From <math>\frac{f}{f_\oplus}=\left(\frac{R_\ast}{R_\odot}\right)^2 \left(\frac{T_\ast}{t_\odot}\right)^4 \left(\frac{d}{\mathrm{1\ AU}}\right)^{-2}</math> Star radius is 1.15 times solar, temperature is 5609 K compared to the [[sun]] 5777 K. Irradiance is given by bolometric luminosity divided by square of distance, flux divided by [[Solar Constant]], ratio relative to Earth.</ref>

Since HD 28185 b orbits in its star's habitable zone, some have speculated on the possibility of life on worlds in the HD 28185 system.<ref>{{cite web|url=http://nai.nasa.gov/news_stories/news_detail.cfm?ID=126|title=Extrasolar Planets with Earth-like Orbits|author=Mullen, L.|access-date=22 July 2006|date=2001|url-status=dead|archive-url=https://web.archive.org/web/20060929070638/http://nai.nasa.gov/news_stories/news_detail.cfm?ID=126|archive-date=29 September 2006}}</ref> While it is unknown whether gas giants can support life, simulations of tidal interactions suggest that HD 28185 b could harbor Earth-mass [[natural satellite|satellites]] in orbit around it for many billions of years.<ref>{{cite journal|bibcode=2002ApJ...575.1087B|author=Barnes, J., O'Brien, D.|title=Stability of Satellites around Close-in Extrasolar Giant Planets|journal=[[Astrophysical Journal]]|volume=575|issue=2|pages=1087&ndash;1093|date=2002|doi=10.1086/341477|arxiv = astro-ph/0205035 |s2cid=14508244 }}</ref> Such moons, if they exist, may be able to provide a [[planetary habitability|habitable]] environment, though it is unclear whether such satellites would form in the first place.<ref>{{cite journal|author1=Canup, R. |author1-link=Robin Canup |author2=Ward, W.|title=A common mass scaling for satellite systems of gaseous planets|journal=[[Nature (journal)|Nature]]|volume=441|date=2006|pages=834&ndash;839|doi=10.1038/nature04860|pmid=16778883|issue=7095|bibcode = 2006Natur.441..834C |s2cid=4327454 }}</ref> Additionally, a small planet in one of the gas giant's [[Trojan point]]s could survive in a habitable orbit for long periods.<ref>{{cite journal|bibcode=2007A&A...474.1023S|title=Survey of the stability region of hypothetical habitable Trojan planets|author1=Schwarz, R. |author2=Dvorak, R. |author3=Süli, Á. |author4=Érdi, B. |journal=[[Astronomy and Astrophysics]]|volume=474|issue=3|pages=1023–1029|doi=10.1051/0004-6361:20077994|date=2007|doi-access=free}}</ref> The high mass of HD 28185 b, of over six Jupiter masses, actually makes either of these scenarios more likely than if the planet was about Jupiter's mass or less.

== See also ==
* [[51 Pegasi b]]
* [[Iota Horologii b]]
* [[Gliese 876 b]]
* [[Yavin]]
* [[Natural satellite habitability|Habitable exomoons]]
==Notes==
<references group="note"/>

== References ==
{{Reflist|refs=

<ref name="Butler2006">{{cite journal | title=Catalog of Nearby Exoplanets | last1=Butler | first1=R. P. | last2=Wright | first2=J. T. | last3=Marcy | first3=G. W. | last4=Fischer | first4=D. A. | last5=Vogt | first5=S. S. | last6=Tinney | first6=C. G. | last7=Jones | first7=H. R. A. | last8=Carter | first8=B. D. | last9=Johnson | first9=J. A. | last10=McCarthy | first10=C. | last11=Penny | first11=A. J. | display-authors=1 | journal=The Astrophysical Journal | volume=646 | issue=1 | pages=505–522 | year=2006 | arxiv=astro-ph/0607493 | bibcode=2006ApJ...646..505B | doi=10.1086/504701 | s2cid=119067572 }}</ref>

<ref name="eso0114">{{cite press release | title=Exoplanets: The Hunt Continues! | date=April 4, 2001 | publisher=European Southern Observatory | location=Garching, Germany | url=http://www.eso.org/public/news/eso0114/ | access-date=December 27, 2012 }}</ref>

<ref name="Feng2022">{{cite journal |last1=Feng |first1=Fabo |last2=Butler |first2=R. Paul |display-authors=etal |date=August 2022 |title=3D Selection of 167 Substellar Companions to Nearby Stars |journal=[[The Astrophysical Journal Supplement Series]] |volume=262 |issue=21 |page=21 |doi=10.3847/1538-4365/ac7e57 |arxiv=2208.12720 |bibcode=2022ApJS..262...21F|s2cid=251864022 |doi-access=free }}</ref>

}}

== External links ==

{{Commons category|HD 28185 b}}

* {{cite web | url=http://media4.obspm.fr/exoplanets/base/etoile.php?nom=HD+28185 | title=HD 28185 | work=Exoplanets | access-date=2008-11-01 | archive-url=https://web.archive.org/web/20160303235656/http://media4.obspm.fr/exoplanets/base/etoile.php?nom=HD+28185 | archive-date=2016-03-03 | url-status=dead }}

{{Sky|04|26|26.3205|-|10|33|02.955|138}}

{{Good article}}{{Eridanus (constellation)}}
{{DEFAULTSORT:Hd 28185 B}}
[[Category:Eridanus (constellation)]]
[[Category:Exoplanets discovered in 2001]]
[[Category:Giant planets in the habitable zone]]
[[Category:Exoplanets detected by radial velocity]]