{{Short description|Star in the constellation Hydra}} {{Starbox begin}} {{Starbox observe | epoch = J2000.0 | constell = [[Hydra (constellation)|Hydra]] | ra = {{RA|11|07|54.427}}<ref name=GaiaDR3/> | dec = {{DEC|−30|10|28.45}}<ref name=GaiaDR3/> | appmag_v = 6.51<ref name=aa552_A64/> }} {{Starbox character | class = G0 V<ref name=aj132_1_161/> | b-v = 0.606<ref name=aa552_A64/> | u-b = | variable = }} {{Starbox astrometry | radial_v = 12.839{{±|0.0105}}<ref name=aa552_A64/> | prop_mo_ra = {{val|−505.371}} | prop_mo_dec = {{val|−132.293}} | pm_footnote = <ref name=GaiaDR3/> | parallax = 39.3975 | p_error = 0.0208 | parallax_footnote = <ref name=GaiaDR3/> | absmag_v = }} {{Starbox detail | mass = {{Val|1.00|0.01}}<ref name=Martos2023/> | radius = {{Val|1.142|0.015|0.016}}<ref name=Soto2018/> | luminosity =1.45<ref name="luck"/> | gravity = {{Val|4.33|0.02}}<ref name=Martos2023/> | temperature = {{Val|5878|6|fmt=commas}}<ref name=Martos2023/> | metal_fe = {{Val|-0.189|0.004}}<ref name=Martos2023/> | rotation = | rotational_velocity = | age_gyr = {{Val|6.80|0.64|0.24}}<ref name=Martos2023/> }} {{Starbox catalog | names = {{odlist | CD=−29°8875 | GJ=412.2 | HD=96700 | HIP=54400 | HR=4328 | SAO=179558 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = HD+96700 | NSTED = HD-96700 | ARICNS = 00841 }} {{Starbox end}}
'''HD 96700''' is a star in the equatorial [[constellation]] of [[Hydra (constellation)|Hydra]]. It has an [[apparent visual magnitude]] of 6.51,<ref name=aa552_A64/> which puts it below the limit that can be seen with the naked eye by a typical observer.<ref name=Weaver1947/> (According to the [[Bortle scale]], it is possible for some observers to see it from dark rural skies.) Based upon [[stellar parallax|parallax]] measurements, this star is around 83 [[light year]]s away from the [[Sun]].<ref name=GaiaDR3/> It is drifting further away with a [[radial velocity]] of 12.8 km/s.<ref name=aa552_A64/>
This is considered a high [[proper motion]] star, shifting its position across the [[celestial sphere]] at a rate of 0.52 [[arc second]]s per year, along a [[position angle]] of 255.21°.<ref name=apjss141_1_187/> It is a member of the [[thin disk]] population of stars and is orbiting the [[Galactic Center|galactic core]] at a mean galactocentric distance of {{Convert|7.17|kpc|kly|abbr=on|lk=on|order=flip}} with an [[orbital eccentricity]] 0.16. The inclination of its galactic orbit carries it no more than {{Convert|290|pc|ly|abbr=on|lk=off|order=flip}} away from the [[galactic plane]].<ref name=aa394_927/>
HD 96700 is a [[G-type main sequence star]] with a [[stellar classification]] of G0 V.<ref name=aj132_1_161/> It has the same mass than the Sun and a lower [[metallicity]].<ref name=Martos2023/> The estimated size is 114% that of the Sun.<ref name=Soto2018/> The [[effective temperature]] of the star's [[stellar atmosphere|outer atmosphere]] is 5,878 K,<ref name=Martos2023/> giving it the yellow-hued glow of a G-type star.<ref name=csiro/> It has an estimated age of 6.8 billion years.<ref name=Martos2023/>
Together with the [[proper motion companion]] CD-27 7781, HD 96700 make a wide [[binary system]]. At an angular distance of 6,867", the [[projected separation]] between both stars is of {{Convert|174000|AU|ly|lk=out|abbr=in}}. The companion is a [[K-type main-sequence star]] of K6V [[spectral type]].<ref name=multiplicity/> The existence of any additional stellar companions at projected distances from 7 to 209 [[astronomical unit]]s is ruled out.<ref name=Mugrauer_Ginski_2015/>
==Planetary system== Two planetary companions have been discovered by the [[High Accuracy Radial Velocity Planet Searcher|HARPS]] instrument, which measures variations in the star's [[radial velocity]] that are presumed to be caused by [[gravitational perturbation]]s from orbiting objects. The innermost planet, HD 96700 b, is orbiting close to the star at a distance of roughly 0.08 [[Astronomical Unit|AU]] with a brief [[orbital period]] of 8.13 days. It has at least nine times the mass of the Earth, and so may be a [[Neptune]]-like planet. But until astronomers can determine the [[orbital inclination]] or directly image the planet, there is no way to know for certain its actual mass.<ref name=HARPS2011/>
The second companion, HD 96700 d, is orbiting at roughly the same distance as [[Mercury (planet)|Mercury]] from the Sun, with a [[semimajor axis]] of 0.42 AU and a period of around 103 days. It may have a relatively high [[Orbital eccentricity|eccentricity]] of 0.4. This object has at least 13 times the mass of the Earth.<ref name=HARPS2011/> A 2017 study found that HD 96700 b does not [[astronomical transit|transit]] its host star.<ref name=Gillon2017/> The existence of both planets was confirmed in 2021, and an additional planetary companion orbiting between them was found,<ref name=Unger2021/> but in 2026 it was found that the radial velocity signal attributed to this planet is likely correlated with [[stellar activity]] indicators, making its existence uncertain.<ref name=Boulkaboul2026/>
{{OrbitboxPlanet begin | name = HD 96700 | table_ref = <ref name=Unger2021/> }} {{OrbitboxPlanet | exoplanet = b | mass_earth = {{val|8.9|0.4|p=≥}} | period = {{val|8.1245|0.0006}} | semimajor = {{val|0.0777|0.0013}} | eccentricity = <0.138 }} {{Orbitbox planet hypothetical | status = disputed<ref name=Boulkaboul2026/> | exoplanet = c | mass_earth = {{val|3.5|0.4|p=≥}} | period = {{val|19.88|0.01}} | semimajor = {{val|0.141|0.002}} | eccentricity = <0.293 }} {{OrbitboxPlanet | exoplanet = d | mass_earth = {{val|12.7|1.0|p=≥}} | period = {{val|103.5|0.1}} | semimajor = {{val|0.424|0.007}} | eccentricity = {{val|0.27|0.08}} }} {{Orbitbox end}}
== References == <references> <ref name=GaiaDR3>{{Cite Gaia DR3|5452492082132835840}}</ref>
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<ref name="luck">{{Cite journal |last=Luck |first=R. Earle |date=2018-03-01 |title=Abundances in the Local Region. III. Southern F, G, and K Dwarfs |bibcode=2018AJ....155..111L |journal=The Astronomical Journal |volume=155 |issue=3 |pages=111 |doi=10.3847/1538-3881/aaa9b5 |doi-access=free |issn=0004-6256}}</ref>
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<ref name=Unger2021>{{citation | title=The HARPS search for southern extra-solar planets XLVI: 12 super-Earths around the solar type stars HD39194, HD93385, HD96700, HD154088, and HD189567 | last1=Unger | first1=N. | last2=Ségransan | first2=D. | last3=Queloz | first3=D. | last4=Udry | first4=S. | last5=Lovis | first5=C. | last6=Mordasini | first6=C. | last7=Ahrer | first7=E. | last8=Benz | first8=W. | last9=Bouchy | first9=F. | last10=Delisle | first10=J. -B. | last11=Díaz | first11=R. F. | last12=Dumusque | first12=X. | last13=Lo Curto | first13=G. | last14=Marmier | first14=M. | last15=Mayor | first15=M. | last16=Pepe | first16=F. | last17=Santos | first17=N. C. | last18=Stalport | first18=M. | last19=Alonso | first19=R. | last20=Collier Cameron | first20=A. | last21=Deleuil | first21=M. | last22=Figueira | first22=P. | last23=Gillon | first23=M. | last24=Moutou | first24=C. | last25=Pollacco | first25=D. | last26=Pompei | first26=E. | display-authors=1 | journal=Astronomy & Astrophysics | volume=654 | id=A104 | pages=19 | date=October 2021 | doi=10.1051/0004-6361/202141351 | arxiv=2108.10198 | bibcode=2021A&A...654A.104U }}</ref>
<ref name=Gillon2017>{{citation | title=The Spitzer search for the transits of HARPS low-mass planets - II. Null results for 19 planets | last1=Gillon | first1=M. | last2=Demory | first2=B. -O. | last3=Lovis | first3=C. | last4=Deming | first4=D. | last5=Ehrenreich | first5=D. | last6=Lo Curto | first6=G. | last7=Mayor | first7=M. | last8=Pepe | first8=F. | last9=Queloz | first9=D. | last10=Seager | first10=S. | last11=Ségransan | first11=D. | last12=Udry | first12=S. | display-authors=1 | journal=Astronomy & Astrophysics | volume=601 | id=A117 | pages=23 | date=May 2017 | doi=10.1051/0004-6361/201629270 | arxiv=1701.01303 | bibcode=2017A&A...601A.117G }}</ref>
<ref name=SIMBAD>{{cite simbad | title=HD 96700 | access-date=2015-12-07 }}</ref> </references> {{Stars of Hydra|state=collapsed}}
<!-- Properties --> [[Category:G-type main-sequence stars]] [[Category:Exoplanets detected by radial velocity]] [[Category:Planetary systems with two confirmed planets]] <!-- Location/catalogues --> [[Category:Hydra (constellation)]] [[Category:Bright Star Catalogue objects|4328]] [[Category:Durchmusterung objects|CD-29 08875]] [[Category:Gliese and GJ objects|0412.2]] [[Category:Henry Draper Catalogue objects|96700]] [[Category:Hipparcos objects|054400]]