{{Short description|G-type star in the constellation Taurus}} {{Starbox begin}} {{Starbox observe | epoch = J2000.0 | constell = Taurus<ref name=Anderson_Francis_2012/> | ra = {{RA|03|50|22.9678}}<ref name=GaiaDR3/> | dec = {{DEC|+17|28|34.925}}<ref name=GaiaDR3/> | appmag_v = 7.50<ref name=Anderson_Francis_2012/> }} {{Starbox character | type = subgiant<ref name=GaiaDR3/> | class = G2V<ref name=Sharma_et_al_2020/> | r-i = | v-r = | b-v = 0.653{{±|0.003}}<ref name=Anderson_Francis_2012/> | u-b = | variable = }} {{Starbox astrometry | radial_v = −9.36{{±|0.08}}<ref name=Anderson_Francis_2012/> | prop_mo_ra = 113.433 | prop_mo_dec = −251.101 | pm_footnote = <ref name=GaiaDR3/> | parallax = 21.4719 | p_error = 0.0241 | parallax_footnote = <ref name=GaiaDR3/> | absmag_v = 4.16<ref name=Anderson_Francis_2012/> }} {{Starbox detail | source = | mass = {{Val|1.220|0.060|0.061}}<ref name=An2025/> | radius = 1.35<ref name=delaverny2025/> | luminosity = 1.79<ref name=delaverny2025/> | gravity = 4.24<ref name=delaverny2025/> | temperature = 5,756<ref name=delaverny2025/> | metal_fe = 0.13<ref name=delaverny2025/> | rotational_velocity = 2.39{{±|0.050}}<ref name="Wright2007"/> | age_gyr = 4.8{{±|0.8}}<ref name="Bonfanti2015"/> }} {{Starbox catalog | names = {{odlist | BD=+17°638 | HD=24040 | HIP=17960 | LTT=11274 | NLTT=11955 | SAO=93630 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = HD+24040 }} {{Starbox end}}

'''HD 24040''' is a star with two orbiting exoplanets in the equatorial constellation of Taurus. The star is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.50.<ref name=Anderson_Francis_2012/> Based on parallax measurements, it is located at a distance of 152&nbsp;light years. However, it is drifting closer to the Sun with a radial velocity of −9.4&nbsp;km/s.<ref name=Anderson_Francis_2012/>

This is a G-type main-sequence star with a stellar classification of G2V.<ref name=Sharma_et_al_2020/> It is a metal-rich star with an age of around 4.8 billion years. The star has 14% more mass than the Sun<ref name=An2025/> and 135% of the Sun's radius. It is radiating 1.8 times the luminosity of the Sun from its photosphere at an effective temperature of {{val|fmt=commas|5756|ul=K}}.<ref name=delaverny2025/> The star is spinning slowly with a projected rotational velocity of 2.4&nbsp;km/s.<ref name="Wright2007"/>

==Planetary system== A long period planet was discovered in 2006 based on observations made at the W. M. Keck Observatory in Hawaii. However, because the observations covered less than one complete orbit there were only weak constraints on the period and mass.<ref name="Wright2007"/> The first reliable orbit for HD 24040b was obtained by astronomers at Haute-Provence Observatory in 2012 who combined the keck measurements with ones from the SOPHIE and ELODIE spectrographs.<ref name="Boisse2012"/> The most recent orbit published in 2015 added additional keck measurements and refined the orbital parameters.<ref name="Feng2015"/>

A linear trend in the radial velocities indicating a possible additional companion was detected at Haute-Provence Observatory and was also detected at keck but at a much smaller amplitude.<ref name="Boisse2012"/><ref name="Feng2015"/> The linear trend was confirmed in 2021, together with the discovery of another planet, HD 24040 c.<ref name=Rosenthal2021/>

In 2025, the use of astrometry allowed the inclination and true mass of planet b to be found. The inclination is likely edge-on, implying a minimum mass very close to the real one.<ref name=An2025/>

{{OrbitboxPlanet begin | table_ref = }} {{OrbitboxPlanet | exoplanet = c<ref name=Rosenthal2021/> | mass = ≥0.201{{±|0.027}} | semimajor = 1.3{{±|0.021}} | period = 515.4{{±|2.2|2.5}} | eccentricity = 0.11{{±|0.120|0.079}} }} {{OrbitboxPlanet | exoplanet = b<ref name=An2025/> | mass = {{val|5.00|0.36|0.26}} | semimajor = {{val|4.817|0.079|0.083}} | period = {{val|3485|15}} | eccentricity = {{val|0.046|0.025|0.026}} | inclination = {{Val|89|20|19}} }} {{Orbitbox end}}

==See also== * HD 154345 * List of extrasolar planets

==References== {{Reflist|refs=

<ref name=SIMBAD>{{cite simbad | title=HD 24040 | access-date = 2023-12-12 }}</ref>

<ref name=GaiaDR3>{{Cite Gaia DR3|43802039287826432}}</ref>

<ref name="Boisse2012">{{cite journal |doi=10.1051/0004-6361/201118419 |arxiv=1205.5835 |title=The SOPHIE search for northern extrasolar planets V. Follow-up of ELODIE candidates: Jupiter-analogs around Sun-like stars |year=2012 | display-authors=1 |last1=Boisse |first1=Isabelle |last2=Pepe |first2=Francesco |last3=Perrier |first3=Christian |last4=Queloz |first4=Didier |last5=Bonfils |first5=Xavier |last6=Bouchy |first6=François |last7=Santos |first7=Nuno C. |last8=Arnold |first8=Luc |last9=Beuzit |first9=Jean-Luc |last10=Dìaz |first10=Rodrigo F. |last11=Delfosse |first11=Xavier |last12=Eggenberger |first12=Anne |last13=Ehrenreich |first13=David |last14=Forveille |first14=Thierry |last15=Hébrard |first15=Guillaume |last16=Lagrange |first16=Anne-Marie |last17=Lovis |first17=Christophe |last18=Mayor |first18=Michel |last19=Moutou |first19=Claire |last20=Naef |first20=Dominique |last21=Santerne |first21=Alexandre |last22=Ségransan |first22=Damien |last23=Sivan |first23=Jean-Pierre |last24=Udry |first24=Stéphane |journal=Astronomy and Astrophysics |volume=545 |pages=A55 |bibcode=2012A&A...545A..55B |s2cid=119109836 }}</ref>

<ref name="Bonfanti2015">{{cite journal | title=Revising the ages of planet-hosting stars | url=http://www.aanda.org/articles/aa/full_html/2015/03/aa24951-14/aa24951-14.html | last1=Bonfanti | first1=A. | last2=Ortolani | first2=S. | last3=Piotto | first3=G. | last4=Nascimbeni | first4=V. | display-authors=1 | journal=Astronomy and Astrophysics | volume=575 | at=A18 | year=2015 | arxiv=1411.4302 | bibcode=2015A&A...575A..18B | doi=10.1051/0004-6361/201424951 | s2cid=54555839 }}</ref>

<ref name="Feng2015">{{cite journal | title=The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-period Planets | last1=Feng | first1=Y. Katherina | last2=Wright | first2=Jason T. | last3=Nelson | first3=Benjamin | last4=Wang | first4=Sharon X. | last5=Ford | first5=Eric B. | last6=Marcy | first6=Geoffrey W. | last7=Isaacson | first7=Howard | last8=Howard | first8=Andrew W. | display-authors=1 | journal=The Astrophysical Journal | volume=800 | issue=1 | at=22 | year=2015 | arxiv=1501.00633 | bibcode=2015ApJ...800...22F | doi=10.1088/0004-637X/800/1/22 | s2cid=56390823 }}</ref>

<ref name="Wright2007">{{cite journal | title=Four New Exoplanets and Hints of Additional Substellar Companions to Exoplanet Host Stars | last1=Wright | first1=J. T. | last2=Marcy | first2=G. W. | last3=Fischer | first3=D. A | last4=Butler | first4=R. P. | 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=Apps | first11=K. | display-authors=1 | journal=The Astrophysical Journal | volume=657 | issue=1 | pages=533–545 | year=2007 | arxiv=astro-ph/0611658 | bibcode=2007ApJ...657..533W | doi=10.1086/510553 | s2cid=35682784 }}</ref>

<ref name=Rosenthal2021>{{cite journal|arxiv=2105.11583|year=2021|title=The California Legacy Survey. I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades | display-authors=1 |last1=Rosenthal|first1=Lee J.|last2=Fulton|first2=Benjamin J.|last3=Hirsch|first3=Lea A.|last4=Isaacson|first4=Howard T.|last5=Howard|first5=Andrew W.|last6=Dedrick|first6=Cayla M.|last7=Sherstyuk|first7=Ilya A.|last8=Blunt|first8=Sarah C.|last9=Petigura|first9=Erik A.|last10=Knutson|first10=Heather A.|last11=Behmard|first11=Aida|last12=Chontos|first12=Ashley|last13=Crepp|first13=Justin R.|last14=Crossfield|first14=Ian J. M.|last15=Dalba|first15=Paul A.|last16=Fischer|first16=Debra A.|last17=Henry|first17=Gregory W.|last18=Kane|first18=Stephen R.|last19=Kosiarek|first19=Molly|last20=Marcy|first20=Geoffrey W.|last21=Rubenzahl|first21=Ryan A.|last22=Weiss|first22=Lauren M.|last23=Wright|first23=Jason T.|journal=The Astrophysical Journal Supplement Series|volume=255|issue=1 |page=8|doi=10.3847/1538-4365/abe23c|bibcode=2021ApJS..255....8R |s2cid=235186973 |doi-access=free }}</ref>

<ref name=Anderson_Francis_2012>{{cite XHIP|17960}}</ref>

<ref name=Sharma_et_al_2020>{{cite journal | title=Application of convolutional neural networks for stellar spectral classification | last1=Sharma | first1=Kaushal | last2=Kembhavi | first2=Ajit | last3=Kembhavi | first3=Aniruddha | last4=Sivarani | first4=T. | last5=Abraham | first5=Sheelu | last6=Vaghmare | first6=Kaustubh | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society | volume=491 | issue=2 | pages=2280–2300 | date=January 2020 | doi=10.1093/mnras/stz3100 | doi-access=free | arxiv=1909.05459 | bibcode=2020MNRAS.491.2280S }}</ref>

<ref name=An2025>{{cite journal |last=An |first=Qier |last2=Brandt |first2=Timothy D. |last3=Brandt |first3=G. Mirek |last4=Venner |first4=Alexander |title=Orbits and Masses for 156 Companions from Combined Astrometry and Radial Velocities, and A Validation of Gaia Non-Single Star Solutions |date=2025-08-11 |journal=The Astrophysical Journal Supplement Series |arxiv=2508.08374}}</ref>

<ref name=delaverny2025>{{cite journal |last1=De Laverny |first1=Patrick |last2=Ligi |first2=Roxanne |last3=Crida |first3=Aurélien |last4=Recio-Blanco |first4=Alejandra |last5=Palicio |first5=Pedro A. |title=The Gaia spectroscopic catalogue of exoplanets and host stars |journal=Astronomy and Astrophysics |date=2025 |volume=699 |pages=A100 |doi=10.1051/0004-6361/202554739 |arxiv=2505.22205 |bibcode=2025A&A...699A.100D }}</ref>

}}

==External links== * {{cite encyclopedia | url=http://exoplanet.eu/star.php?st=HD+24040 | archive-url=https://web.archive.org/web/20070224012726/http://exoplanet.eu/star.php?st=HD+24040 | url-status=dead | archive-date=February 24, 2007 | encyclopedia=Extrasolar Planets Encyclopaedia | title=Notes for star HD 24040 }} {{Sky|03|50|22.9681|+|17|28|34.919|151.7}}

{{Stars of Taurus}}

<!-- Properties -->

Category:G-type main-sequence stars Category:Planetary systems with two confirmed planets <!-- Location/catalogues --> Category:Taurus (constellation) Category:Durchmusterung objects 024040 017960