View source for HD 40307

{{Short description|Star in the constellation Pictor}}
{{Starbox begin
| name = [[Henry Draper Catalogue|HD]] 40307
}}
{{Starbox image
| image = [[Image:Location of HD 40307.png|250px]]
| caption = Location of HD 40307 in the night sky. The star is marked within the red diamond below the word "Pictor".
}}
{{Starbox observe
| epoch = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
| constell = [[Pictor]]
| ra = {{RA|05|54|04.24050}}<ref name="GaiaDR3"/>
| dec = {{DEC|−60|01|24.4930}}<ref name="GaiaDR3"/>
| appmag_v = 7.17<ref name=sb />
}}
{{Starbox character
| class = K2.5V<ref name=sb />
| u-b =
| b-v = 0.93<ref name=sb />
| v-r =
| r-i =
}}
{{Starbox astrometry
| radial_v = {{val|31.08|0.12}}<ref name="GaiaDR3"/>
| prop_mo_ra = {{val|−52.174|0.023}}
| prop_mo_dec = {{val|−60.059|0.025}}
| pm_footnote = <ref name="GaiaDR3"/>
| parallax = 77.3261
| p_error = 0.0170
| parallax_footnote = <ref name="GaiaDR3"/>
| absmag_v = {{val|6.57|0.01}}<ref name=cgssn09 />
}}
{{Starbox detail
| mass = 0.75{{±|0.03|0.04}}<ref name="geneva">[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/117A/newcat&recno=3947 HD 40307], database entry, Geneva-Copenhagen Survey of Solar neighbourhood, J. Holmberg et al., 2007, [[Centre de Données astronomiques de Strasbourg|CDS]] database [http://vizier.u-strasbg.fr/viz-bin/Cat?V/117A V/117A], accessed November 19, 2008; described in The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14 000 F and G dwarfs, B. Nordström, M. Mayor, J. Andersen, J. Holmberg, F. Pont, B. R. Jørgensen, E. H. Olsen, S. Udry, and N. Mowlavi, ''[[Astronomy and Astrophysics]]'' '''418''' (May 2004), pp. 989–1019, {{bibcode|2004A&A...418..989N}}, {{doi|10.1051/0004-6361:20035959}}.</ref>
| radius = 0.716 ± 0.010<ref name="2massphot">[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=J/A%2bA/450/735/table2&recno=2686 HD 40307], entry, [[Centre de Données astronomiques de Strasbourg|CDS]] database [http://cdsarc.u-strasbg.fr/viz-bin/Cat?J/A%2bA/450/735 J/A+A/450/735]; described in Effective temperature scale and bolometric corrections from 2MASS photometry, E. Masana, C. Jordi, and I. Ribas, ''Astronomy and Astrophysics'' '''450''', #2 (May 2006), pp. 735–746. {{bibcode|2006A&A...450..735M}}. {{doi|10.1051/0004-6361:20054021}}.</ref>
| gravity = 4.47 ± 0.16<ref name="mayor08">{{cite journal|display-authors= 7|author= M. Mayor|author2= S. Udry|author3= C. Lovis|author4= F. Pepe|author5= D. Queloz|author6= W. Benz|author7= J.-L. Bertaux|author8= F. Bouchy|author9= C. Mordasini|author10= D. Segransan|title=The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)|journal=[[Astronomy and Astrophysics]]|bibcode=2009A&A...493..639M|arxiv=0806.4587|doi=10.1051/0004-6361:200810451|date= 2009|volume= 493|issue= 2|pages= 639–644|s2cid= 116365802}}</ref>
| luminosity_bolometric = 0.23<ref name="mayor08" />
| luminosity_visual = 0.20<ref group="note">Using the absolute visual magnitude of HD 40307 <math>\scriptstyle M_{V_{\ast}}=6.57</math> and the absolute visual magnitude of the Sun <math>\scriptstyle M_{V_{\odot}}=4.83</math>, the visual luminosity can be calculated by <math>\scriptstyle \frac{L_{V_{\ast}}}{L_{V_{\odot}}}=10^{0.4\left(M_{V_{\odot}} - M_{V_{\ast}}\right)}</math></ref>
| temperature =  4977 ± 59<ref name="mayor08" />
| metal_fe = −0.31 ± 0.03<ref name="mayor08" />
| rotation = {{val|31.8|6.7|u=d}}<ref name=mnras452_3_2745/>
| rotational_velocity = 3<ref name=geneva />
| age_gyr = 1.2&nbsp;(≥&nbsp;0.2)<ref name=geneva />
}}
{{Starbox catalog
| names = [[Durchmusterung|CD]]−60&nbsp;1303, [[Durchmusterung|CPD]]−60&nbsp;508, [[Boss General Catalogue|GC]]&nbsp;7474, [[Gliese-Jahreiss catalogue|GJ]]&nbsp;2046, [[Hipparcos Catalogue|HIP]]&nbsp;27887, [[PPM Star Catalogue|PPM]]&nbsp;355061, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;249388, [[2MASS]] J05540421-6001245.<ref name=sb />
}}
{{Starbox reference
| Simbad = HD+40307
| NSTED = HD+40307
| ARICNS = 02347
| EPE = HD+40307
}}
{{starbox end
}}
'''HD 40307''' is an orange ([[K-type star|K-type]]) [[main sequence|main-sequence]] [[star]] located approximately 42 [[light-year]]s away in the [[constellation]] of [[Pictor]] (the [[Easel]]), taking its primary name from its [[Henry Draper Catalogue]] designation.  It is calculated to be slightly less massive than the [[Sun]].   The star has six known [[extrasolar planet|planets]], three discovered in 2008<ref name=sb /><ref name=msnbc>{{cite web |url=http://www.nbcnews.com/id/25191635 |archive-url=https://web.archive.org/web/20131213170111/http://www.nbcnews.com/id/25191635/ |url-status=dead |archive-date=December 13, 2013 |title=Three super-Earths found around one star |author=Jeanna Bryner |website=NBC News |date=June 16, 2008 |access-date=June 18, 2008 }}</ref> and three more in 2012. One of them, [[HD 40307 g]], is a potential [[super-Earth]] in the [[habitable zone]], with an orbital period of about 200 days. This object might be capable of supporting liquid water on its surface, although much more information must be acquired before its habitability can be assessed.<ref name="latimes-nov12">{{cite web |url=http://www.latimes.com/news/science/sciencenow/la-sci-sn-earthlike-planet-water-atmosphere-red-light-20121107,0,2600859.story |title=Possible Earth-like planet could hold water; scientists cautious |author=Amina Khan |website=Los Angeles Times |date=November 7, 2012 |access-date=November 8, 2012 }}</ref><ref name="tuomi12">{{cite journal |doi=10.1051/0004-6361/201220268 |last1=Tuomi |first1=Mikko |last2=Anglada-Escudé |first2=Guillem |last3=Gerlach |first3=Enrico |last4=Jones |first4=Hugh R. A. |last5=Reiners |first5=Ansgar |last6=Rivera |first6=Eugenio J. |last7=Vogt |first7=Steven S. |last8=Butler |first8=R. Paul |title=Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307 |journal=Astronomy & Astrophysics |date=17 December 2012 |volume=549 |pages=A48 |arxiv=1211.1617 |bibcode=2013A&A...549A..48T |s2cid=7424216 }}</ref><ref name="Space-20121107a">{{cite web |last=Wall |first=Mike |title='Super-Earth' Alien Planet May Be Habitable for Life |url=http://www.space.com/18393-alien-planet-super-earth-habitable-hd-40307g.html |date=November 7, 2012 |publisher=[[Space.com]] |access-date=November 8, 2012 }}</ref><ref name="Space-20121107b">{{cite web |last=Tate |first=Karl |title=Super-Earth Planet: Potentially Habitable Alien World Explained (Infographic) |url=http://www.space.com/18390-super-earth-exoplanet-habitable-zone-infographic.html |date=November 7, 2012 |publisher=[[Space.com]] |access-date=November 8, 2012 }}</ref>

No stellar companions to HD 40307 were detected as of 2018.<ref>{{cite journal |arxiv=1811.09666 |doi=10.1051/0004-6361/201731341 |title=Archival VLT/Na ''Co'' multiplicity investigation of exoplanet host stars |year=2018 |last1=Dietrich |first1=J. |last2=Ginski |first2=C. |journal=Astronomy & Astrophysics |volume=620 |pages=A102 |bibcode=2018A&A...620A.102D |s2cid=119294338 }}</ref>

== History and nomenclature ==
HD 40307 was observed during or before 1900 as part of the [[Cape Photographic Durchmusterung]].<ref>[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/108/cpd&recno=379090 CPD−60&nbsp;508], database entry, Cape Photographic Durchmusterung (CPD), D. Gill and J. C. Kapetyn, 1895–1900, [[Centre de Données astronomiques de Strasbourg|CDS]] ID [http://cdsarc.u-strasbg.fr/viz-bin/Cat?I/108 I/108].</ref>  The designation ''HD 40307'' is from the [[Henry Draper Catalogue]], which is based on spectral classifications made between 1911 and 1915 by [[Annie Jump Cannon]] and her co-workers, and was published between 1918 and 1924.<ref>pp. 214–215 in The Henry Draper Memorial, Annie J. Cannon, ''Journal of the Royal Astronomical Society of Canada'' '''9''', #5 (May–June 1915), pp. 203–215, {{bibcode|1915JRASC...9..203C}}.</ref><ref>The Henry Draper Catalogue, Annie J. Cannon and Edward C. Pickering, ''Annals of Harvard College Observatory'';<br />hours 0 to 3, '''91''' (1918), {{bibcode|1918AnHar..91....1C}};<br />hours 4 to 6, '''92''' (1918), {{bibcode|1918AnHar..92....1C}};<br />hours 7 to 8, '''93''' (1919), {{bibcode|1919AnHar..93....1C}};<br />hours 9 to 11, '''94''' (1919), {{bibcode|1919AnHar..94....1C}};<br />hours 12 to 14, '''95''' (1920), {{bibcode|1920AnHar..95....1C}};<br />hours 15 to 16, '''96''' (1921), {{bibcode|1921AnHar..96....1C}};<br />hours 17 to 18, '''97''' (1922), {{bibcode|1922AnHar..97....1C}};<br />hours 19 to 20, '''98''' (1923), {{bibcode|1923AnHar..98....1C}};<br />hours 21 to 23, '''99''' (1924), {{bibcode|1924AnHar..99....1C}}.</ref>

== Characteristics ==
As a K-type star, HD 40307 emits orange-tinted light.<ref name=sb /> It has only about three-quarters of the [[Sun]]'s radius and mass.<ref name="geneva" /> Its temperature is measured at slightly under {{val|5000|fmt=commas|ul=K}}.

The astronomers who discovered the planets orbiting HD 40307 suggested that the [[metallicity|metallicities]] of stars determine whether or not the planetary bodies that orbit them will be terrestrial, like Earth, or gaseous, like [[Jupiter]] and [[Saturn]].<ref name="mayor08"/>

=== Distance and visibility ===
Despite its relative proximity to the Sun at 42 light-years, HD 40307 is not visible to the naked eye, given its [[apparent magnitude]] of 7.17.<ref>{{cite web |url=http://csep10.phys.utk.edu/astr162/lect/stars/magnitudes.html|title=Stellar Magnitudes|access-date=20 November 2008 |work=Astrophysics 162 Unit|publisher=[[University of Tennessee]]|date=2008}}</ref>  It came within 6.4 light-years of the Sun about 413,000 years ago.<ref name="Bobylev:arXiv1003.2160">{{cite journal |last=Bobylev |first=Vadim V. |date=March 2010 |title=Searching for Stars Closely Encountering with the Solar System |journal=Astronomy Letters  |volume=36 |issue=3 |pages=220–226  |doi=10.1134/S1063773710030060  |arxiv=1003.2160 |bibcode=2010AstL...36..220B|s2cid=118374161}}</ref>

== Planetary system ==
A planetary system around HD 40307 contains four confirmed planets and two other possible planets, all within {{val|0.6|ul=AU}} of the star.
{{OrbitboxPlanet begin
| table_ref = <ref name="tuomi12" /><ref name=Diaz2016/><ref>{{Cite journal|arxiv=2009.14164|doi=10.1051/0004-6361/202039168|title=Determining the true mass of radial-velocity exoplanets with Gaia|year=2021|last1=Kiefer|first1=F.|last2=Hébrard|first2=G.|last3=Lecavelier Des Etangs|first3=A.|last4=Martioli|first4=E.|last5=Dalal|first5=S.|last6=Vidal-Madjar|first6=A.|journal=Astronomy & Astrophysics|volume=645|pages=A7|bibcode=2021A&A...645A...7K |s2cid=221995447}}</ref>
}}
{{OrbitboxPlanet
| exoplanet = [[HD 40307 b|b]]
| mass_earth = ≥ 4.0 {{±|0.8|0.7}} <!-- upper limit 3.741 Jupiter masses -->
| period = 4.3123 {{±|0.0011|0.0012}}
| semimajor = 0.0468 {{±|0.0023|0.0024}}
| eccentricity = 0.20 {{±|0.16|0.14}}
| inclination = >0.2022
}}
{{OrbitboxPlanet
| exoplanet = [[HD 40307 c|c]]
| mass_earth = ≥ 6.6 {{±|1.1|1.0}} <!-- upper limit 5.879 Jupiter masses -->
| period = 9.6184 {{±|0.0050|0.0049}}
| semimajor = 0.0799 ± 0.0040
| eccentricity = 0.06 {{±|0.06|0.11}}
| inclination = >0.2109
}}
{{OrbitboxPlanet
| exoplanet = [[HD 40307 d|d]]
| mass_earth = ≥ 9.5 {{±|1.7|1.5}} <!-- upper limit 5.586 Jupiter masses -->
| period = 20.432 {{±|0.022|0.024}}
| semimajor = 0.1321 {{±|0.0066|0.0064}}
| eccentricity = 0.07 {{±|0.11|0.07}}
| inclination = >0.2855
}}
{{OrbitboxPlanet hypothetical
| exoplanet = [[HD 40307 e|e]]
| mass_earth = ≥ 3.5 ± 1.4
| period = 34.62 {{±|0.21|0.20}}
| semimajor = 0.1886 {{±|0.083|0.0104}}
| eccentricity = 0.15 {{±|0.13|0.15}}
|status=disputed
}}
{{OrbitboxPlanet
| exoplanet = [[HD 40307 f|f]]
| mass_earth = ≥ 5.2 {{±|1.5|1.6}}
| period = 51.76 {{±|0.50|0.46}}
| semimajor = 0.247 {{±|0.011|0.014}}
| eccentricity = 0.02 {{±|0.20|0.02}}
}}
{{OrbitboxPlanet hypothetical
| exoplanet = [[HD 40307 g|g]]
| mass_earth = ≥ 7.1 ± 2.6
| period = 197.8 {{±|9.0|5.7}}
| semimajor = 0.600 {{±|0.034|0.033}}
| eccentricity = 0.29 {{±|0.31|0.29}}
|status=disputed
}}
{{Orbitbox end}}

[[Image:HD40307.svg|thumb|250px|left|The orbits of the inner three planets of HD 40307.]]
After spending five years observing the star,<ref name=SOL>{{cite web |url=http://www.solstation.com/stars2/hd40307.htm|title=HD 40307 / CD-60 1303|access-date=27 November 2008 |work=SolStation |publisher=Sol Company |date=2008 }}</ref> the [[European Organisation for Astronomical Research in the Southern Hemisphere]] (''ESO'') announced that they had discovered three [[super-Earth]]s in orbit around HD 40307 in June 2008. All three planets were detected by the [[radial velocity]] method, using the [[High Accuracy Radial Velocity Planet Searcher|HARPS]] spectrograph system.<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/sci/tech/7457307.stm|title=Trio of 'super-Earths' discovered |author=Mayor|display-authors=etal|date=2008-06-16|work=BBC News|access-date=2008-06-16}}</ref>

In 2012, an independent analysis carried out by a team of astronomers led by [[Mikko Tuomi]] of the University of Hertfordshire confirmed the existence of these planets and found an additional three planets in the systems.<ref name="latimes-nov12" /><ref name="tuomi12" /> The planet [[HD 40307 f]] on 51.6-day orbit was confirmed in 2015, with inconclusive evidence for the planets [[HD 40307 e]] and [[HD 40307 g]].<ref name=Diaz2016>{{cite journal | title=The HARPS search for southern extra-solar planets. XXXVIII. Bayesian re-analysis of three systems. New super-Earths, unconfirmed signals, and magnetic cycles | last1=Díaz | first1=R. F. | last2=Ségransan | first2=D. | last3=Udry | first3=S. | last4=Lovis | first4=C. | last5=Pepe | first5=F. | last6=Dumusque | first6=X. | last7=Marmier | first7=M. | last8=Alonso | first8=R. | last9=Benz | first9=W. | last10=Bouchy | first10=F. | last11=Coffinet | first11=A. | last12=Collier Cameron | first12=A. | last13=Deleuil | first13=M. | last14=Figueira | first14=P. | last15=Gillon | first15=M. | last16=Lo Curto | first16=G. | last17=Mayor | first17=M. | last18=Mordasini | first18=C. | last19=Motalebi | first19=F. | last20=Moutou | first20=C. | last21=Pollacco | first21=D. | last22=Pompei | first22=E. | last23=Queloz | first23=D. | last24=Santos | first24=N. | last25=Wyttenbach | first25=A. | display-authors=1 | journal=Astronomy and Astrophysics | volume=585 | at=A134 | year=2016 | arxiv=1510.06446 | bibcode=2016A&A...585A.134D | doi=10.1051/0004-6361/201526729 | s2cid=118531921 }}</ref>

Five of the planets orbit very close to the star,<ref name="tuomi12" /> with the farthest of them located twice as close to HD 40307 than is the planet [[Mercury (planet)|Mercury]] is to the [[Sun]].<ref>{{cite web|title=Mercury Fact Sheet|url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html|publisher=[[NASA]] Goddard Space Flight Center | date=November 30, 2007 |access-date=2008-11-12}}</ref><ref group=note>Mercury orbits at approx. 0.39 AU</ref> The outermost planet orbits at a distance similar to the distance of [[Venus (planet)|Venus]] to the [[Sun]] and is situated well in the system's [[Extraterrestrial liquid water|liquid water]] [[habitable zone]].<ref name="tuomi12" />

The [[minimum mass]]es of the planets in the system ranges from three to ten times the [[Earth mass|mass of the Earth]], placing them somewhere between [[Earth]] and gas giants like [[Uranus]] and [[Neptune]].<ref name="tuomi12" /> Dynamical analysis of the innermost planets suggests that planet [[HD 40307 b|b]] is unstable at its age unless it is an ice giant, having migrated from further away. That implies similar for the other planets, even further out.<ref>{{cite journal|last1=Barnes|first1=Rory|date=January 13, 2009|title=The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?|journal=The Astrophysical Journal|arxiv=0901.1698|bibcode = 2009ApJ...695.1006B |doi = 10.1088/0004-637X/695/2/1006|last2=Jackson|first2=Brian|last3=Raymond|first3=Sean N.|last4=West|first4=Andrew A.|last5=Greenberg|first5=Richard|volume=695|issue=2|pages=1006–1011 |s2cid=18849636}}</ref> The most recent discovery also indicates via dynamical analysis that the true planetary masses can not be much higher than their minimum masses.<ref name="tuomi12" />

{{clear}}
== See also ==
*[[List of multiplanetary systems]]
* [[List of extrasolar planets]]
* Other stars with planets discovered in June 2008:
** [[HD 181433]]
** [[HD 47186]]
** [[MOA-2007-BLG-192L]]

== Notes ==
<references group="note" />

== References ==
{{Reflist|refs=

<ref name=sb>{{SIMBAD link|HD+40307|HD 40307}}, entry, [[SIMBAD]].  Accessed online June 18, 2008.</ref>

<ref name="GaiaDR3">{{Cite Gaia DR3|4758877919212831104}}</ref>

<ref name=mnras452_3_2745>{{cite journal
 | display-authors=1
 | last1=Suárez Mascareño | first1=A. | last2=Rebolo | first2=R.
 | last3=González Hernández | first3=J. I. | last4=Esposito | first4=M.
 | title=Rotation periods of late-type dwarf stars from time series high-resolution spectroscopy of chromospheric indicators
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=452 | issue=3 | pages=2745–2756 | date=September 2015
 | doi=10.1093/mnras/stv1441 | doi-access=free | bibcode=2015MNRAS.452.2745S
 | arxiv=1506.08039
}}</ref>

<ref name=cgssn09>{{cite journal
 | display-authors=1 | last1=Holmberg | first1=J.
 | last2=Nordström | first2=B. | last3=Andersen | first3=J.
 | title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics
 | journal=Astronomy and Astrophysics
 | volume=501 | issue=3 |date=July 2009 | pages=941–947
 | doi=10.1051/0004-6361/200811191 | bibcode=2009A&A...501..941H
 | arxiv=0811.3982 | s2cid=118577511 }}[https://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ5e1271ea4813&-out.add=.&-source=V/130/gcs3&recno=3947 VizieR]</ref>
}}

== External links ==
{{Commons category|HD 40307}}
* [https://web.archive.org/web/20081007085709/http://www.eso.org/public/outreach/press-rel/pr-2008/pr-19-08.html A Trio of Super-Earths: A harvest of low-mass exoplanets discovered with HARPS], press release, [[European Southern Observatory]], ESO 19/08, June 16, 2008.

{{Sky|05|54|04.2409|-|60|01|24.498|41.8}}
{{Good article}}

{{HD 40307}}
{{Stars of Pictor}}
{{2012 in space}}

{{DEFAULTSORT:HD 40307}}
[[Category:HD 40307| ]]
[[Category:Henry Draper Catalogue objects|040307]]
[[Category:Hipparcos objects|027887]]
[[Category:Gliese and GJ objects|2046]]
[[Category:Durchmusterung objects|CD-60 01303]]
[[Category:K-type main-sequence stars]]
[[Category:Solar-type stars|HD, 040307]]
[[Category:Pictor]]
[[Category:Planetary systems with four confirmed planets]]
[[Category:2MASS objects|J05540421-6001245]]