Rho Herculis

{{Short description|Binary star in the constellation Hercules}}

{{Starbox begin|name=Rho Herculis}}

{{Starbox observe 2s

|epoch=J2000

|constell=Hercules

|component1=ρ Her A

|ra1={{RA|17|23|40.972}}{{cite journal|title=The Tycho-2 catalogue of the 2.5 million brightest stars|author=Høg, E.|display-authors=etal|date=2000|journal=Astronomy and Astrophysics|volume=355|pages=L27–L30|bibcode=2000A&A...355L..27H}}

|dec1={{DEC|+37|08|45.33}}

|appmag_v1=4.510

|component2=ρ Her B

|ra2={{RA|17|23|40.718}}

|dec2={{DEC|+37|08|48.44}}

|appmag_v2=5.398

}}

{{Starbox character

|component1=ρ Her A

|class=A0IIIpHgMn{{cite journal|bibcode=1995ApJS...99..135A|doi=10.1086/192182|title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars|journal=The Astrophysical Journal Supplement Series|volume=99|pages=135|year=1995|last1=Abt|first1=Helmut A.|last2=Morrell|first2=Nidia I.|doi-access=free}}

|b-v=+0.00{{cite journal|title=UBVRIJKL Photometry of the Bright Stars|author1=Johnson, H. L.|journal=Communications of the Lunar and Planetary Laboratory|volume=4|pages=99|date=1966|bibcode=1966CoLPL...4...99J}}

|u-b=−0.06

|component2=ρ Her B

|class2=B9.5IVn

}}

{{Starbox astrometry

|component1=ρ Her A

|radial_v=−21.0 ± 2{{cite journal|title=General catalogue of stellar radial velocities|journal=Carnegie Institute Washington D.C. Publication|pages=0|author=Wilson, Ralph Elmer|date=1953|bibcode=1953GCRV..C......0W}}

|prop_mo_ra=−38.6{{cite journal|author1=Zacharias, N.|title=The fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)|journal=VizieR On-line Data Catalog|date=2012|bibcode=2012yCat.1322....0Z}}

|prop_mo_dec=9.2

|parallax=8.3380

|p_error=0.3358

|parallax_footnote={{cite DR2|1337345927125084416}}

|component2=ρ Her B

|radial_v2=−19.3 ± 2

|prop_mo_ra2=−38.6

|prop_mo_dec2=9.2

|parallax2=9.0354

|p_error2=0.1135

|parallax_footnote2={{cite DR2|1337345922829546752}}

}}

{{Starbox detail

|component1=A

|mass=4.00/2.93{{cite web|url=http://www.ctio.noao.edu/~atokovin/stars/stars.php?cat=HD&number=157779|title=Multiple Star Catalog|access-date=2018-11-30|website=Cerro Tololo Inter-American Observatory|archive-date=2018-12-01|archive-url=https://web.archive.org/web/20181201005235/http://www.ctio.noao.edu/~atokovin/stars/stars.php?cat=HD&number=157779|url-status=dead}}

|radius=

|temperature=9,118

|luminosity=

|gravity=

|rotational_velocity=75{{cite journal|bibcode=2002A&A...393..897R|title=Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin I|journal=Astronomy and Astrophysics|volume=393|issue=3|pages=897–911|last1=Royer|first1=F.|last2=Grenier|first2=S.|last3=Baylac|first3=M. -O.|last4=Gómez|first4=A. E.|last5=Zorec|first5=J.|year=2002|doi=10.1051/0004-6361:20020943 |arxiv=astro-ph/0205255|doi-access=free}}

|age_myr=

|component2 = B

|mass2=3.27

|temperature2=8,755

|rotational_velocity2=291

|gravity2=3.6{{cite journal|bibcode=2016A&A...589A..83G|title=A new method for the inversion of atmospheric parameters of A/Am stars|journal=Astronomy and Astrophysics|volume=589|pages=A83|last1=Gebran|first1=M.|last2=Farah|first2=W.|last3=Paletou|first3=F.|last4=Monier|first4=R.|last5=Watson|first5=V.|year=2016|doi=10.1051/0004-6361/201528052|arxiv=1603.01146|s2cid=118549566}}

|metal_fe=0.0

}}

{{Starbox catalog

|names={{odlist|ADS=10526 AB|CCDM=J17236+3708AB|BD=+37°2878|HIP=85112}}

|component1=ρ Her A

|names1={{odlist|HD=157779|HR=6485|SAO=66001}}

|component2=ρ Her B

|names2={{odlist|HD=157778|HR=6484|SAO=66000}}

}}

{{Starbox reference

|Simbad=rho+Her|sn=ρ Her

|Simbad2=rho+Her+A|sn2=ρ Her A

|Simbad3=rho+Her+B|sn3=ρ Her B

}}

{{Starbox end}}

Rho Herculis (ρ Her, ρ Herculis) is a double star in the constellation of Hercules. The apparent magnitudes of the components are 4.510 and 5.398, respectively. Parallax measurements published in Gaia Data Release 2 put the system at some 360-390 light-years (111-121 parsecs) away.

The two stars of Rho Herculis are separated by four arcseconds, and are known as Rho Herculis A and B, respectively. A is an A-type giant star, while B is a B-type subgiant star. They are also referred to, rarely, as Rho¹ Herculis and Rho² Herculis. Rho Herculis A is itself a close binary which has been resolved using speckle interferometry, with the two components separated by {{val|0.252|ul="}}.{{cite journal|bibcode=2009AJ....137.3358M|title=The High Angular Resolution Multiplicity of Massive Stars|journal=The Astronomical Journal|volume=137|issue=2|pages=3358|last1=Mason|first1=Brian D.|last2=Hartkopf|first2=William I.|last3=Gies|first3=Douglas R.|last4=Henry|first4=Todd J.|last5=Helsel|first5=John W.|year=2009|doi=10.1088/0004-6256/137/2/3358|arxiv=0811.0492|s2cid=119268845}}

The two visual components have very similar spectral types, between A0 and B9. Rho Herculis A is generally assigned a giant luminosity class, with Rho Herculis B most often considered to be a main sequence star.{{cite journal|bibcode=2014yCat....1.2023S|title=VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016)|journal=VizieR On-line Data Catalog|last1=Skiff|first1=B. A.|year=2014}} Rho Herculis A has been considered to be an Ap star, with unusually strong silicon or mercury and manganese absorption lines in its spectrum,{{cite journal|bibcode=1984ApJ...276..266A|title=The nature of the visual companions of AP and AM stars|journal=The Astrophysical Journal|volume=276|pages=266|last1=Abt|first1=H. A.|last2=Cardona|first2=O.|year=1984|doi=10.1086/161610}} but this is now considered to be dubious.{{cite journal|bibcode= 2009A&A...498..961R |title= Catalogue of Ap, HgMn and Am stars |journal= Astronomy and Astrophysics |volume= 498 |issue= 3 |pages= 961 |last1= Renson |first1= P. |last2= Manfroid |first2= J. |year= 2009 |doi= 10.1051/0004-6361/200810788 |doi-access= free }}