{{Short description|Star in the constellation Hercules}} {{about-distinguish|b Herculis|beta Herculis{{!}}β (Beta) Herculis}} {{Starbox begin}} {{Starbox image | image = {{Location mark |image=Hercules constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=99 Herculis |x=335|y=535 }} | caption = Location of 99 Herculis (circled in red) }} {{Starbox observe | epoch = J2000 | constell = Hercules | ra = {{RA|18|07|01.53971}}<ref name="AAA474_2_653"/> | dec = {{DEC|+30|33|43.6896}}<ref name="AAA474_2_653"/> | appmag_v = 5.066<ref name="Rakos1982"/> {{nowrap|(A: 5.10; B: 8.45)}}<ref name="Eggen1965"/> }} {{Starbox character | class = F7 V<ref name="Maldonado2012"/> + K4 V<ref name="Kennedy2012"/> | r-i = | v-r = | b-v = +0.548<ref name="Rakos1982"/> | u-b = –0.056<ref name="Rakos1982"/> | variable = }} {{Starbox astrometry | radial_v = +1.7<ref name="Nordström2004"/> | prop_mo_ra = −100.32<ref name="AAA474_2_653"/> | prop_mo_dec = +110.08<ref name="AAA474_2_653"/> | parallax = 63.93 | p_error = 0.34 | parallax_footnote = <ref name="AAA474_2_653"/> | absmag_v = 4.08<ref name="Takeda2005"/> }} {{Starbox orbit | reference = <ref name="Kennedy2012"/> | period = {{val|56.3|0.1}} | axis = {{val|1.06|0.02}} | eccentricity = {{val|0.766|0.004}} | inclination = {{val|39|2}} | node = {{val|41|2}} | periastron = {{val|1997.62|0.05}} | periarg = {{val|116|2}} }} {{Starbox detail | component1 = 99 Her A | mass = 1.14<ref name=hu2023/> | radius = 1.34<ref name=hu2023/> | gravity = 4.17<ref name="Maldonado2012"/> | metal_fe = –0.60<ref name="Maldonado2012"/> | temperature = 5,908<ref name=hu2023/> | luminosity = 1.90<ref name=hu2023/> | rotational_velocity = 5<ref name="Takeda2005"/> | age_gyr = 9.37<ref name="Maldonado2012"/> | component2 = 99 Her B | mass2 = 0.46<ref name="Kennedy2012"/> | temperature2 = 4,449<ref name=houdebine2009/> | radius2 = 0.67<ref name=houdebine2009/> | luminosity2 = 0.19<ref name=kral2017/> }} {{Starbox catalog | names = {{odlist | B=b Her | F=99 Her | BD=+30°3128 | GJ=704 | HD=165908 | HIP=88745 | HR=6775 | SAO=66648 }}<ref name="SIMBAD"/> }} {{Starbox reference | Simbad = *+99+Her | sn=A | Simbad3 = *+b+Her+B | sn3=B }} {{Starbox end}}
'''99 Herculis''' is the Flamsteed designation for a binary star system in the northern constellation of Hercules. It has the Bayer designation '''b Herculis''', while ''99 Herculis'' is the Flamsteed designation. This system has an apparent visual magnitude of 5.1,<ref name="Rakos1982"/> which, according to the Bortle scale, makes it faintly visible to the naked eye from suburban skies. Measurements made with the Hipparcos spacecraft show an annual parallax shift of 0.064″,<ref name="AAA474_2_653"/> corresponding to a physical distance of about {{Convert|51.0|ly|pc|abbr=on}} from the Sun. The system is moving further from the Earth with a heliocentric radial velocity of +1.7 km/s.<ref name="Nordström2004"/>
The binary nature of this star system was first discovered in 1859 by English astronomer W. R. Dawes.<ref name="vanBiesbroeck1947"/> The two stellar components orbit around their common center of mass, or barycenter, with a period of 56.3 years and an eccentricity of 0.766. The semi-major axis of their orbit spans an angle of 1.06 arcseconds, which corresponds to a physical dimension of 16.5 AU. The plane of their orbit is inclined by an angle of about 39° to the line-of-sight from the Earth. Reports of a third component of this system now appear doubtful.<ref name="Kennedy2012"/>
== System == The primary component, 99 Herculis A, is an F-type main sequence star with a stellar classification of F7 V.<ref name="Maldonado2012"/> It is 13% more mass than the Sun and nearly double the luminosity, but has an estimated 34% greater radius. The effective temperature of the star's outer atmosphere is {{val|fmt=commas|5,908|ul=K}},<ref name=hu2023/> giving it a white-hued glow.<ref name="csiro"/> This is a metal-poor star, showing overall abundances of elements—other than hydrogen or helium—equal to 60% of those in the Sun.<ref name="Adelman2000"/>
The secondary component, 99 Herculis B, is fainter by 3.35 magnitudes compared to the primary. It is a K-type main sequence star with a classification of K4 V.<ref name="Kennedy2012"/> With 46% of the mass of the Sun,<ref name="Kennedy2012"/> it is 67% of the radius of the Sun<ref name=houdebine2009/> but shines with just 19% of the Sun's luminosity.<ref name=kral2017/>
=== Debris disk === Images from the Herschel Space Observatory show that a narrow disk of dusty debris is orbiting the barycenter at an average radius of 120 AU. Oddly, the disk appears to be misaligned with the orbital plane of the binary system and is instead aligned with the poles. This may be the result of an interaction within another star system some time in the past. Most of the disk emission appears to be caused by icy objects having a diameter of 10 cm or less, with a net mass of about ten times the mass of the Earth.<ref name="Kennedy2012"/>
It is hypothesized that the debris disk is being sculpted by several (likely two) polar circumbinary planets due to the disk being truncated in some regions. Simulations of this system that only have a single planet are insufficient to explain the morphology of the disk as that planet only truncates one edge of the disk leaving the other edge extended. Simulation that have two planets successfully model what is seen in the debris disk of 99 Herculis as they can carve out the disk on both edges leaving a narrow debris disk.<ref>{{cite journal |last1=Smallwood |first1=Jeremy L. |title=The polar debris disc around 99 Herculis: A potential signpost for polar circumbinary planets |date=2026 |arxiv=2510.08698 |last2=DeRocco |first2=William |last3=Qin |first3=Zhizhen |last4=Sefilian |first4=Antranik A. |journal=Monthly Notices of the Royal Astronomical Society |volume=545 |issue=4 |article-number=staf1982 |doi=10.1093/mnras/staf1982 |doi-access=free |bibcode=2026MNRAS.545f1982S }}</ref>
==References== {{Reflist|refs=
<ref name=hu2023>{{cite journal |last1=Hardegree-Ullman |first1=Kevin K. |last2=Apai |first2=Dániel |last3=Bergsten |first3=Galen J. |last4=Pascucci |first4=Ilaria |last5=López-Morales |first5=Mercedes |title=Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O<SUB>2</SUB> Levels in Nearby Transiting Habitable-zone Exoplanets |journal=The Astronomical Journal |date=2023 |volume=165 |issue=6 |page=267 |doi=10.3847/1538-3881/acd1ec |doi-access=free |arxiv=2304.12490 |bibcode=2023AJ....165..267H }}</ref>
<ref name=kral2017>{{cite journal |last1=Kral |first1=Quentin |last2=Matrà |first2=Luca |last3=Wyatt |first3=Mark C. |last4=Kennedy |first4=Grant M. |title=Predictions for the secondary CO, C and O gas content of debris discs from the destruction of volatile-rich planetesimals |journal=Monthly Notices of the Royal Astronomical Society |date=2017 |volume=469 |issue=1 |page=521 |doi=10.1093/mnras/stx730 |doi-access=free |arxiv=1703.10693 |bibcode=2017MNRAS.469..521K }}</ref>
<ref name=houdebine2009>{{cite journal |last1=Houdebine |first1=Éric R. |last2=Mullan |first2=D. J. |last3=Doyle |first3=J. G. |last4=de la Vieuville |first4=Geoffroy |last5=Butler |first5=C. J. |last6=Paletou |first6=F. |title=The Mass-Activity Relationships in M and K Dwarfs. I. Stellar Parameters of Our Sample of M and K Dwarfs |journal=The Astronomical Journal |date=2019 |volume=158 |issue=2 |page=56 |doi=10.3847/1538-3881/ab23fe |doi-access=free |arxiv=1905.07921 |bibcode=2019AJ....158...56H }}</ref>
<ref name="AAA474_2_653">{{cite journal | first=F. | last=van Leeuwen | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | date=2007 | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | arxiv=0708.1752 | s2cid=18759600 }}</ref>
<ref name="Maldonado2012">{{cite journal | display-authors=1 | last1=Maldonado | first1=J. | last2=Eiroa | first2=C. | last3=Villaver | first3=E. | last4=Montesinos | first4=B. | last5=Mora | first5=A. | title=Metallicity of solar-type stars with debris discs and planets | journal=Astronomy & Astrophysics |date=May 2012 | volume=541 | page=A40 | arxiv=1202.5884 | bibcode=2012A&A...541A..40M | doi=10.1051/0004-6361/201218800 | s2cid=46328823 }}</ref>
<ref name="Nordström2004">{{cite journal | last1=Nordström | first1=B. | last2=Mayor | first2=M. | last3=Andersen | first3=J. | last4=Holmberg | first4=J. | last5=Pont | first5=F. | last6=Jørgensen | first6=B. R. | last7=Olsen | first7=E. H. | last8=Udry | first8=S. | last9=Mowlavi | first9=N. | display-authors=1 | title=The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14,000 F and G dwarfs | journal=Astronomy and Astrophysics | volume=418 | issue=3 | pages=989–1019 |date=May 2004 | doi=10.1051/0004-6361:20035959 | bibcode=2004A&A...418..989N | arxiv=astro-ph/0405198 | s2cid=11027621 }}</ref>
<ref name="Takeda2005">{{citation | display-authors=1 | last1=Takeda | first1=Yoichi | last2=Sato | first2=Bun'ei | last3=Kambe | first3=Eiji | last4=Masuda | first4=Seiji | last5=Izumiura | first5=Hideyuki | last6=Watanabe | first6=Etsuji | last7=Ohkubo | first7=Michiko | last8=Yanagisawa | first8=Kenshi | last9=Yasaka | first9=Yoshiro | title=High-Dispersion Spectra Collection of Nearby F--K Stars at Okayama Astrophysical Observatory: A Basis for Spectroscopic Abundance Standards | journal=Publications of the Astronomical Society of Japan | volume=57 | issue=1 | pages=13–25 |date=February 2005 | bibcode=2005PASJ...57...13T | postscript=. | doi=10.1093/pasj/57.1.13 | doi-access=free}}</ref>
<ref name="Rakos1982">{{citation | last1=Rakos | first1=K. D. | last2=Albrecht | first2=R. | last3=Jenkner | first3=H. | last4=Kreidl | first4=T. | last5=Michalke | first5=R. | last6=Oberlerchner | first6=D. | last7=Santos | first7=E. | last8=Schermann | first8=A. | last9=Schnell | first9=A. | last10=Weiss | first10=W. | display-authors=1 | title=Photometric and astrometric observations of close visual binaries | journal=Astronomy and Astrophysics Supplement Series | volume=47 | pages=221–235 |date=February 1982 | bibcode=1982A&AS...47..221R | postscript=. }}</ref>
<ref name="Kennedy2012">{{cite journal | last1=Kennedy | first1=G. M. | last2=Wyatt | first2=M. C. | last3=Sibthorpe | first3=B. | last4=Duchêne | first4=G. | last5=Kalas | first5=P. | last6=Matthews | first6=B. C. | last7=Greaves | first7=J. S. | last8=Su | first8=K. Y. L. | last9=Fitzgerald | first9=M. P. | display-authors=1 | title=99 Herculis: host to a circumbinary polar-ring debris disc | journal=Monthly Notices of the Royal Astronomical Society | date=2012 | volume=421 | issue=3 | pages=2264–2276 | doi=10.1111/j.1365-2966.2012.20448.x | doi-access=free | bibcode=2012MNRAS.421.2264K | arxiv=1201.1911 | s2cid=53710762 }}</ref>
<ref name="SIMBAD">{{cite simbad | title=b Her | access-date=2013-10-10 }}</ref>
<ref name="Adelman2000">{{citation | last1=Adelman | first1=Saul J. | last2=Caliskan | first2=Hulya | last3=Kocer | first3=Dursun | last4=Cay | first4=Ipek H. | last5=Gokmen Tektunali | first5=H. | display-authors=1 | title=Elemental abundance analyses with DAO spectrograms - XXIII. The superficially normal stars 28 And (A7III) and 99 Her (F7V) | journal=Monthly Notices of the Royal Astronomical Society | volume=316 | issue=3 | pages=514–518 |date=August 2000 | doi=10.1046/j.1365-8711.2000.03577.x | bibcode=2000MNRAS.316..514A | postscript=. | doi-access=free }}</ref>
<ref name="csiro">{{citation |title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=Commonwealth Scientific and Industrial Research Organisation |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |access-date=2012-01-16 |postscript=. |url-status=dead |archive-url=https://web.archive.org/web/20120318151427/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archive-date=March 18, 2012 }}</ref>
<ref name="vanBiesbroeck1947">{{citation | last1=van Biesbroeck | first1=G. | title=The orbit of 99 Herculis = Alvan Clark 15 | journal=Astronomical Journal | volume=53 | pages=23–24 | year=1947 | doi=10.1086/106040 | bibcode=1947AJ.....53...23V | postscript=. | doi-access=free }}</ref>
<ref name="Eggen1965">{{citation | last1=Eggen | first1=O. J. | title=Masses, luminosities, colors, and space motions of 228 visual binaries | journal=Astronomical Journal | volume=70 | page=90 |date=February 1965 | doi=10.1086/109676 | bibcode=1965AJ.....70...19E | postscript=. }}</ref>
}}
{{Stars of Hercules}} {{Sky|18|07|01.54|+|30|33|43.69}}
<!-- Properties -->
Category:F-type main-sequence stars Category:K-type main-sequence stars Category:Binary stars Category:Circumstellar disks <!-- Catalogues --> Category:Hercules (constellation) Herculis, b BD+30 3128 Herculis, 099 0704 165908 088745 6775