{{Short description|Star in the constellation Hydra}} {{Starbox begin}} {{Starbox image | image = [[Image:V478HyaLightCurve.png|250px]] | caption = A [[light curve]] for V478 Hydrae, plotted from ''[[Transiting Exoplanet Survey Satellite|TESS]]'' data<ref name=MAST/> }} {{Starbox observe | epoch = J2000.0 | constell = [[Hydra (constellation)|Hydra]] | ra = {{RA|08|22|49.95277}}<ref name=GaiaDR3/> | dec = {{DEC|+01|51|33.5522}}<ref name=GaiaDR3/> | appmag_v = 8.66-8.77<ref name=Samus2017/> }} {{Starbox character | type = [[main sequence]]<ref name=GaiaDR3/> | class = G1/2V<ref name=Houk1999/> | b-v = 0.59<ref name=Lopez2006/> | u-b = | variable = [[BY Draconis variable|BY Dra]]<ref name=Samus2017/> }} {{Starbox astrometry | radial_v = {{val|20.16|0.22}}<ref name=GaiaDR3/> | prop_mo_ra = {{val|-51.362|0.017}} | prop_mo_dec = {{val|-49.047|0.013}} | pm_footnote = <ref name=GaiaDR3/> | parallax = 16.9267 | p_error = 0.0168 | parallax_footnote = <ref name=GaiaDR3/> | absmag_v = +0.4<ref name=Setiawan2007/> }} {{Starbox detail | mass = {{Val|1.0|0.1}}<ref name=Setiawan2007/> | radius = {{Val|0.98|0.01|0.03}}<ref name=GaiaDR2/> | gravity = {{Val|4.59|0.10}}<ref name=Setiawan2007/> | metal_fe = {{Val|−0.18|0.20}}<ref name=Setiawan2007/> | luminosity = {{Val|0.998|0.004}}<ref name=GaiaDR2/> | temperature = {{Val|5837|80|51|fmt=commas}}<ref name=GaiaDR2/> | rotational_velocity = {{Val|14.7|1.0}}<ref name=Setiawan2007/> | rotation = 3.296 days<ref name=Setiawan2007/> | age_gyr = {{Val|2.3|2.1}}<ref name=LDA2021/> }} {{Starbox catalog | names = {{odlist | BD=+02°1951 | SAO=116694 | V=V478 Hya | HD=70573 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = HD+70573 }} {{Starbox end}}
'''HD 70573''' is a [[variable star]] in the [[celestial equator|equatorial]] [[constellation]] of [[Hydra (constellation)|Hydra]]. At a mean [[apparent visual magnitude]] of +8.7, this yellow-hued star is too dim to be visible to the naked eye. Based upon [[stellar parallax|parallax]] measurements, it is located at a distance of 193 [[light year]]s from the [[Sun]], and is drifting further away with a [[radial velocity]] of 20.5 km/s. It is a candidate member of the proposed Hercules-Lyra Association of co-moving stars,<ref name=Lopez2006/> although this membership is disputed.<ref name=Eisenbeiss2013/>
This is a [[G-type main-sequence star]] with a [[stellar classification]] of G1/2V.<ref name=Houk1999/> It is a [[BY Draconis variable]] that ranges in brightness from magnitude 8.66 down to 8.77 with a rotationally-modulated period of 3.296 days.<ref name=Samus2017/> HD 70573 is generally considered to be a young star although estimates of its age vary from 60<ref name=Meshkat2017/> million years to several billion years.<ref name=LDA2021/> It has a [[projected rotational velocity]] of 15 km/s<ref name=Setiawan2007/> and about the same mass, size, and luminosity as the Sun.
==Planetary system== On March 19, 2007, an [[extrasolar planet]] was announced, having been discovered by the [[radial velocity]] method. As of 2007, this was the youngest host star discovered to have an orbiting planet.<ref name=Setiawan2007/> However, a follow-up study by Soto et al. in 2015 failed to detect the planetary signal, so it remains unconfirmed.<ref name=Soto2015/>
The system displays an [[infrared excess]], which matches the [[black body]] signature of a [[debris disk]] orbiting {{Val|21.8|ul=AU}} from the host star with a mean temperature of 60 K.<ref name=Cotten2016/>
{{OrbitboxPlanet begin | table_ref = <ref name=Setiawan2007/> }} {{OrbitboxPlanet hypothetical | exoplanet = b | mass = {{Val|6.1|0.4|p=≥}} | period = {{Val|851.8|11.6}} | semimajor = {{Val|1.76|0.05}} | eccentricity = {{Val|0.4|0.1}} }} {{Orbitbox end}}
==References== <references> <ref name=SIMBAD>{{cite simbad | title=HD 70573 | access-date=2020-01-08 }}</ref>
<ref name=GaiaDR2>{{Cite Gaia DR2|3090083696499829376}}</ref>
<ref name=GaiaDR3>{{Cite Gaia DR3|3090083696499829376}}</ref>
<ref name=Houk1999>{{cite journal | title=Michigan catalogue of two-dimensional spectral types for the HD Stars | journal=Michigan Spectral Survey | last1=Houk | first1=N. | last2=Swift | first2=C. | volume=5 | year=1999 | bibcode=1999MSS...C05....0H }}</ref>
<ref name=MAST>{{cite web | title=MAST: Barbara A. Mikulski Archive for Space Telescopes | url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html | publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>
<ref name=Setiawan2007>{{cite journal | last1=Setiawan | last2=Weise | first2=P. | last3=Henning | first3=Th. | last4=Launhardt | first4=R. | last5=Müller | first5=A. | last6=Rodmann | first6=J. | title=Evidence for a Planetary Companion around a Nearby Young Star | display-authors=1 | journal=The Astrophysical Journal Letters | year=2007 | volume=660 | issue=2 | pages=L145–L148 | doi=10.1086/518213 | arxiv=0704.0441 | bibcode=2007ApJ...660L.145S | s2cid=18721503 }}</ref>
<ref name=Lopez2006>{{cite journal | last1=López-Santiago | first1=J. | last2=Montes | first2=D. | last3=Crespo-Chacón | first3=I. | last4=Fernández-Figueroa | first4=M. J. | title=The Nearest Young Moving Groups | display-authors=1 | journal=The Astrophysical Journal | volume=643 | issue=2 | pages=1160–1165 | year=2006 | doi=10.1086/503183 | bibcode=2006ApJ...643.1160L | arxiv=astro-ph/0601573 | s2cid=119520529 }}</ref>
<ref name=Meshkat2017>{{cite journal | title=A Direct Imaging Survey of Spitzer-detected Debris Disks: Occurrence of Giant Planets in Dusty Systems | display-authors=1 | last1=Meshkat | first1=Tiffany | last2=Mawet | first2=Dimitri | last3=Bryan | first3=Marta L. | last4=Hinkley | first4=Sasha | last5=Bowler | first5=Brendan P. | last6=Stapelfeldt | first6=Karl R. | last7=Batygin | first7=Konstantin | last8=Padgett | first8=Deborah | last9=Morales | first9=Farisa Y. | last10=Serabyn | first10=Eugene | last11=Christiaens | first11=Valentin | last12=Brandt | first12=Timothy D. | last13=Wahhaj | first13=Zahed | journal=The Astronomical Journal | volume=154 | issue=6 | id=245 | pages=21 | date=December 2017 | doi=10.3847/1538-3881/aa8e9a | arxiv=1710.04185 | bibcode=2017AJ....154..245M | s2cid=42042014 | doi-access=free }}</ref>
<ref name=Cotten2016>{{cite journal | title=A Comprehensive Census of Nearby Infrared Excess Stars | last1=Cotten | first1=Tara H. | last2=Song | first2=Inseok | journal=The Astrophysical Journal Supplement Series | volume=225 | issue=1 | id=15 | pages=24 | date=July 2016 | bibcode=2016ApJS..225...15C | arxiv=1606.01134 | doi=10.3847/0067-0049/225/1/15 | s2cid=118438871 | doi-access=free }}</ref>
<ref name=Eisenbeiss2013>{{cite journal | title=The Hercules-Lyra association revisited. New age estimation and multiplicity study | last1=Eisenbeiss | first1=T. | last2=Ammler-von Eiff | first2=M. | last3=Roell | first3=T. | last4=Mugrauer | first4=M. | last5=Adam | first5=Ch. | last6=Neuhäuser | first6=R. | last7=Schmidt | first7=T. O. B. | last8=Bedalov | first8=A. | display-authors=1 | journal=Astronomy & Astrophysics | volume=556 | id=A53 | pages=19 | date=August 2013 | arxiv=1312.4045 | bibcode=2013A&A...556A..53E | doi=10.1051/0004-6361/201118362 | s2cid=119275785 }}</ref>
<ref name=Samus2017>{{cite journal | display-authors=1 | last1=Samus | first1=N. N. | last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V. | last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N. | title=General Catalogue of Variable Stars | version=5.1 | journal=Astronomy Reports | year=2017 | volume=61 | issue=1 | pages=80–88 | doi=10.1134/S1063772917010085 | bibcode=2017ARep...61...80S | s2cid=125853869 }}</ref>
<ref name = LDA2021>{{cite journal |last1=Llorente de Andrés |first1=F. |last2=Chavero |first2=C. |last3=de la Reza |first3=R. |last4=Roca-Fàbrega |first4=S. |last5=Cifuentes |first5=C. |title=The evolution of lithium in FGK dwarf stars. The lithium-rotation connection and the Li desert |journal=Astronomy and Astrophysics |date=October 2021 |volume=654 |pages=A137 |doi=10.1051/0004-6361/202141339 |bibcode=2021A&A...654A.137L |issn=0004-6361 |arxiv=2108.05852 |doi-access=free}}</ref>
<ref name=Soto2015>{{cite journal | title=RAFT - I. Discovery of new planetary candidates and updated orbits from archival FEROS spectra | display-authors=1 | last1=Soto | first1=M. G. | last2=Jenkins | first2=J. S. | last3=Jones | first3=M. I. | journal=Monthly Notices of the Royal Astronomical Society | volume=451 | issue=3 | pages=3131–3144 | date=August 2015 | doi=10.1093/mnras/stv1144 | doi-access=free | arxiv=1505.04796 | bibcode=2015MNRAS.451.3131S }}</ref> </references>
==External links== * {{cite encyclopedia | url=http://exoplanet.eu/star.php?st=HD+70573 | archive-url=https://web.archive.org/web/20070613004732/http://exoplanet.eu/star.php?st=HD+70573 | url-status=dead | archive-date=June 13, 2007 | encyclopedia=[[Extrasolar Planets Encyclopaedia]] | title=Notes for star HD 70573 }} {{Sky|08|22|49.9514|+|01|51|33.552|149}}
{{Stars of Hydra}} <!-- Properties -->
[[Category:G-type main-sequence stars]] [[Category:BY Draconis variables]] [[Category:Circumstellar disks]] [[Category:Hypothetical planetary systems]] <!-- Identifiers --> [[Category:Hydra (constellation)]] [[Category:Durchmusterung objects]] [[Category:Henry Draper Catalogue objects|070573]] [[Category:Objects with variable star designations|Hydrae, V478]]