HD 85709

{{Short description|Suspected variable in Sextans}} {{Starbox begin | name = [[Henry Draper Catalogue|HD]] 85709 }} {{Starbox image | image = {{Location mark | image = Sextans constellation map.svg | float = center | width = 260 | position = right | mark = Red circle.svg | mark_width = 6 | mark_link = HD 85709 | x = 678 | y = 280 }} | caption = Location of HD 85709 on the map (circled) }} {{Starbox observe | epoch = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Sextans]]<ref name = Anderson2012/> | ra = {{RA|09|53|42.92424}}<ref name = GaiaDR3/> | dec = {{DEC|+05|57|30.8742}}<ref name = GaiaDR3/> | appmag_v = 5.95<ref name = Ducati2002/> (5.89 - 5.95)<ref name = Kornilov1991/> }} {{Starbox character | type = [[asymptotic giant branch|AGB]]<ref name = Eggen1992/> | class = M2.5 III<ref name = Wilson1950/> | b-v = +1.66<ref name = Johnson1966/> | u-b = +1.93<ref name = Johnson1966/> | variable = suspected<ref name = Samus2017/> }} {{Starbox astrometry | radial_v = −0.66{{±|0.40}}<ref name = Famaey2005/> | parallax = 2.9474 | p_error = 0.107 | parallax_footnote = <ref name = GaiaDR3/> | prop_mo_ra = −3.026 | prop_mo_dec = +1.315 | pm_footnote = <ref name = GaiaDR3/> | absmag_v = −1.30<ref name = Anderson2012/> }} {{Starbox detail | mass = | radius = 133{{±|7}}<ref name = Kervella2004/> | luminosity = 1,918{{±|144}}<ref name = GaiaDR2/> | gravity = 0.469<ref name = McDonald2017/> | temperature = 3,622{{±|125}}<ref name = McDonald2017/> | metal_fe = +0.23<ref name = Zhou1991/> | rotational_velocity = | age_gyr = }} {{Starbox catalog | names = {{odlist|Gould = 14 G. Sextantis<ref name = Gould1879/>|HD = 85709|AG = +06°1262|BD = +06°2224|GC = 13608|HIP = 48519|HR = 3915|NSV = 18292|SAO = 117975}} }} {{Starbox reference | Simbad = HR+3915 }} {{Starbox end}}

'''HD 85709''' ('''HR 3915; 14 G. Sextantis; NSV 18292''') is a solitary [[star]]<ref name = Eggleton2008/> located in the [[celestial equator|equatorial]] [[constellation]] [[Sextans]]. It is faintly visible to the [[naked eye]] as a red-hued point of light with an [[apparent magnitude]] of 5.95.<ref name = Ducati2002/> The object is located relatively far at a distance of 1,100 [[light-year]]s based on [[Gaia DR3]] [[parallax]] measurements but it is slowly drifting closer with a heliocentric [[radial velocity]] of {{val|-0.66|ul=km/s}}.<ref name = Famaey2005/> At its current distance, HD 85709's brightness is diminished with an [[interstellar extinction]] of two-tenths of a [[magnitude (astronomy)|magnitude]]<ref name = Gontcharov2017/> and it has an [[absolute magnitude]] of −1.30.<ref name = Anderson2012/>

HD 85709 has a [[stellar classification]] of M2.5 III,<ref name = Wilson1950/> indicating that it is an [[stellar evolution|evolved]] [[M-type star|M-type]] [[giant star]]. It is currently on the [[asymptotic giant branch]],<ref name = Eggen1992/> the point where it is generating energy via the fusion of [[hydrogen]] and [[helium]] shells around an inert [[carbon]] [[stellar core|core]]. Having expanded to 133 times the [[radius of the Sun]],<ref name = Kervella2004/> it now radiates 1,918 times the [[luminosity of the Sun]]<ref name = GaiaDR2/> from its enlarged [[photosphere]] at an [[effective temperature]] of {{val|3622|ul=K|fmt=commas}}.<ref name = McDonald2017/> HD 85709 is metal enriched with an [[iron]] abundance 1.58 times that of the [[Sun]]'s.<ref name = Zhou1991/>

In 1991, [[astronomer]] V.G. Kornilov and colleagues observed that HD 85709 fluctuated between magnitudes 5.89 and 5.95 in [[optical light]] during a photometry survey.<ref name = Kornilov1991/> As of 2004 however, its variability has not been confirmed.<ref name = Samus2004/>

==References== {{reflist||refs=

<ref name = Ducati2002>{{cite journal | last1 = Ducati | first1 = J. R. | title = VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system. | journal = VizieR Online Data Catalog | date = 2002 | volume = 2237 | bibcode = 2002yCat.2237....0D}}</ref>

<ref name = Wilson1950>{{cite journal | last1 = Wilson | first1 = Ralph E. | last2 = Joy | first2 = Alfred H. | title = Radial Velocities of 2111 Stars. | journal = The Astrophysical Journal | date = March 1950 | volume = 111 | page = 221 | issn = 0004-637X | eissn = 1538-4357 | s2cid = 122883647 | doi = 10.1086/145261 | bibcode = 1950ApJ...111..221W | doi-access = free}}</ref>

<ref name = Johnson1966>{{cite journal | last1 = Johnson | first1 = H. L. | last2 = Mitchell | first2 = R. I. | last3 = Iriarte | first3 = B. | last4 = Wisniewski | first4 = W. Z. | title = UBVRIJKL Photometry of the Bright Stars | journal = Communications of the Lunar and Planetary Laboratory | year = 1966 | volume = 4 | pages = 99–110 | bibcode = 1966CoLPL...4...99J}}</ref>

<ref name = Eggen1992>{{cite journal |last1=Eggen |first1=Olin J. |title=Asymptotic giant branch stars near the sun |journal=The Astronomical Journal |date=July 1992 |volume=104 |pages=275 |doi=10.1086/116239 |issn=0004-6256 |bibcode=1992AJ....104..275E |s2cid=121672252 |doi-access=free}}</ref>

<ref name = Samus2017>{{cite journal | 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 GCVS 5.1 | journal = Astronomy Reports | date = January 2017 | volume = 61 | issue = 1 | pages = 80–88 | issn = 1063-7729 | eissn = 1562-6881 | doi = 10.1134/S1063772917010085 | bibcode = 2017ARep...61...80S| s2cid = 125853869 }}</ref>

<ref name = Famaey2005>{{cite journal | bibcode = 2005A&A...430..165F | title = Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters | journal = Astronomy and Astrophysics | volume = 430 | pages = 165 | last1 = Famaey | first1 = B. | last2 = Jorissen | first2 = A. | last3 = Luri | first3 = X. | last4 = Mayor | first4 = M. | last5 = Udry | first5 = S. | last6 = Dejonghe | first6 = H. | last7 = Turon | first7 = C. | date = January 2005 | doi = 10.1051/0004-6361:20041272 | arxiv = astro-ph/0409579 | s2cid = 17804304 | doi-access = free}}</ref>

<ref name = McDonald2017>{{cite journal | last1 = McDonald | first1 = I. | last2 = Zijlstra | first2 = A. A. | last3 = Watson | first3 = R. A. | title = Fundamental parameters and infrared excesses of Tycho–Gaia stars | journal = Monthly Notices of the Royal Astronomical Society | date = 15 June 2017 | volume = 471 | issue = 1 | pages = 770–791 | issn = 0035-8711 | eissn = 1365-2966 | doi = 10.1093/mnras/stx1433 | bibcode = 2017MNRAS.471..770M | arxiv = 1706.02208 | s2cid = 73594365 | doi-access = free }}</ref>

<ref name = Kervella2004>{{cite journal | last1 = Kervella | first1 = P. | last2 = Thévenin | first2 = F. | last3 = Di Folco | first3 = E. | last4 = Ségransan | first4 = D. | title = The angular sizes of dwarf stars and subgiants: Surface brightness relations calibrated by interferometry | journal = Astronomy & Astrophysics | date = April 8, 2004 | volume = 426 | issue = 1 | pages = 297–307 | issn = 0004-6361 | eissn = 1432-0746 | doi = 10.1051/0004-6361:20035930 | s2cid = 6077801 | bibcode = 2004A&A...426..297K | arxiv = astro-ph/0404180 | doi-access = free}}</ref>

<ref name = Zhou1991>{{cite journal |last1=Zhou |first1=Xu |title=The near-IR NA I doublet and CA II triplet in late-type stars and the determination of stellar atmosphere parameters. |journal=Astronomy and Astrophysics |date=August 1991 |volume=248 |pages=367 |issn=0004-6361 |bibcode=1991A&A...248..367Z}}</ref>

<ref name = Gould1879>{{cite journal | last = Gould | first = Benjamin Apthorp | title = Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas | journal = Resultados del Observatorio Nacional Argentino | volume = 1 | bibcode = 1879RNAO....1.....G | year = 1878}}</ref>

<ref name = Gontcharov2017>{{cite journal | last1 = Gontcharov | first1 = George A. | last2 = Mosenkov | first2 = Aleksandr V. | title = Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars | journal = Monthly Notices of the Royal Astronomical Society | date = 28 September 2017 | volume = 472 | issue = 4 | pages = 3805–3820 | issn = 0035-8711 | eissn = 1365-2966 | doi = 10.1093/mnras/stx2219 | bibcode = 2017MNRAS.472.3805G | arxiv = 1709.01160 | s2cid = 118879856 | doi-access = free}}</ref>

<ref name = Eggleton2008>{{cite journal | last1 = Eggleton | first1 = P. P. | last2 = Tokovinin | first2 = A. A. | title = A catalogue of multiplicity among bright stellar systems | journal = Monthly Notices of the Royal Astronomical Society | date = 11 September 2008 | volume = 389 | issue = 2 | pages = 869–879 | issn = 0035-8711 | eissn = 1365-2966 | doi = 10.1111/j.1365-2966.2008.13596.x | bibcode = 2008MNRAS.389..869E | arxiv = 0806.2878 | s2cid = 14878976 | doi-access = free }}</ref>

<ref name = Kornilov1991>{{cite journal |last1=Kornilov |first1=V. G. |last2=Volkov |first2=I. M. |last3=Zakharov |first3=A. I. |last4=Kozyreva |first4=V. S. |last5=Kornilova |first5=L. N. |last6=Krutyakov |first6=A. N. |last7=Krylov |first7=A. V. |last8=Kusakin |first8=A. V. |last9=Leont'ev |first9=S. E. |last10=Mironov |first10=A. V. |last11=Moshkalev |first11=V. G. |last12=Pogrosheva |first12=T. M. |last13=Sementsov |first13=V. N. |last14=Khaliullin |first14=Kh. F. |title=Catalogue of WBVR-magnitudes of bright stars of the northern sky. |journal=Trudy Gosudarstvennogo Astronomicheskogo Instituta |date=1991 |volume=63 |pages=4–399 |issn=0371-6791 |bibcode=1991TrSht..63....1K}}</ref>

<ref name = Samus2004>{{cite journal |last1=Samus |first1=N. N. |last2=Durlevich |first2=O. V. |title=VizieR Online Data Catalog: Combined General Catalogue of Variable Stars (Samus+ 2004) |journal=VizieR Online Data Catalog |date=November 2004 |pages=II/250 |bibcode=2004yCat.2250....0S}}</ref>

}} {{Stars of Sextans}}

[[Category:M-type giants]] [[Category:Suspected variables]] [[Category:Asymptotic-giant-branch stars]] [[Category:Sextans]] [[Category:Gould objects|Sextantis, 14]] [[Category:Durchmusterung objects|BD+06 02224]] [[Category:Henry Draper Catalogue objects|085709]] [[Category:Hipparcos objects|048519]] [[Category:Bright Star Catalogue objects|3915]] [[Category:Population I stars]]