U Aquarii: Difference between revisions
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{{distinguish|Upsilon Aquarii}} |
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{{Starbox begin |
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{{short description|Star in the constellation of Aquarius}} |
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| name = [[Variable star designation|U Aquarii]]}} |
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{{Starbox begin}} |
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{{Starbox image |
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| image = [[Image:UAqrLightCurve.png|250px]] |
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| caption = The [[Photometric_system#Photometric_letters|visual band]] [[light curve]] of U Aquarii, from AAVSO data<ref name="aavso"/> |
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}} |
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{{Starbox observe |
{{Starbox observe |
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| epoch = [[J2000.0]] |
| epoch = [[J2000.0]] |
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| equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) |
| equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) |
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| constell = [[Aquarius (constellation)|Aquarius]] |
| constell = [[Aquarius (constellation)|Aquarius]] |
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| ra = {{RA|22|03|19.69905}}<ref name=edr3/> |
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| ra = {{RA|22|03|19.6992}}<ref name=sb0>{{SIMBAD link|U+Aqr|V* U Aqr -- Variable Star of R CrB type}}, database entry, [[SIMBAD]]. Accessed on line November 10, 2009.</ref> |
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| dec = {{DEC|−16|37|35. |
| dec = {{DEC|−16|37|35.2811}}<ref name=edr3/> |
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| appmag_v = 10.6 to 15.9<ref name=Samus_et_al_2017/> |
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| appmag_v=10.6 to 15.9<ref name=gcvs1>U Aqr, database entry, [http://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/iii.dat The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars], Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 10, 2009.</ref> |
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}} |
}} |
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{{Starbox character |
{{Starbox character |
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| |
| type = |
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| class = C-Hd<ref name=Bond_et_al_1979/> |
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| b-v = 0.66<ref name=Lawson_et_al_1990/> |
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| u-b = 0.07<ref name=Lawson_et_al_1990/> |
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| variable = [[R Coronae Borealis variable|R CrB]]<ref name=Samus_et_al_2017/> |
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}} |
}} |
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{{Starbox astrometry |
{{Starbox astrometry |
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| |
| radial_v = {{val|+89.49|1.54}}<ref name=GaiaDR2/> |
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| prop_mo_ra = 2.780<ref name=edr3/> |
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| prop_mo_dec = −1.907<ref name=edr3/> |
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| parallax = 3.58 |
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| |
| parallax = 0.0859 |
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| p_error = 0.0222 |
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| parallax_footnote = <ref name=sb0 /> |
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| parallax_footnote = <ref name=edr3/> |
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| absmag_v= 6<ref group=NB>From apparent magnitude and parallax.</ref> |
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| absmag_v = |
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}} |
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{{Starbox detail |
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| source = |
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| mass = 4.5<ref name=starhorse/> |
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| radius = |
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| gravity = 2.28<ref name=starhorse/> |
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| luminosity = |
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| temperature = 5,500<ref name=Lawson_et_al_1990/> |
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| metal_fe = −0.99<ref name=starhorse/> |
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| rotational_velocity = 8.4<ref name=majewski2017/> |
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| rotation = |
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| age_gyr = |
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}} |
}} |
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{{Starbox catalog |
{{Starbox catalog |
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| names=U Aqr |
| names = {{odlist | V=U Aqr | BD=−17°6424 | HIP=108876 | IRAS=22006-1652 }}<ref name=SIMBAD/> |
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}} |
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{{Starbox reference |
{{Starbox reference |
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| Simbad=U+Aqr}} |
| Simbad = U+Aqr |
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}} |
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{{Starbox end}} |
{{Starbox end}} |
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'''U Aquarii''' |
'''U Aquarii''', abbreviated '''U Aqr''', is a [[variable star]] in the [[celestial equator|equatorial]] [[constellation]] of [[Aquarius (constellation)|Aquarius]]. It is invisible to the naked eye, having an [[apparent visual magnitude]] that ranges from 10.6 down to as low as 15.9.<ref name=Samus_et_al_2017 /> Based on [[stellar parallax|parallax]] measurements, the distance to this star is approximately {{convert|38|kly|kpc|abbr=on|lk=on}}. In 1990, W. A. Lawson and associates provided a distance estimate of {{convert|13.2|kpc|kly|order=flip|abbr=on|lk=off}} based on the assumption of a [[bolometric magnitude]] of −5.<ref name=Lawson_et_al_1990/> It appears to lie several kiloparsecs below the galactic plane, and thus may belong to an old stellar population.<ref name=Bond_et_al_1979/> |
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The [[stellar classification]] of this star is C-Hd,<ref name=Bond_et_al_1979/> and it is classified as a [[R Coronae Borealis variable]].<ref name=Samus_et_al_2017/> It is a [[carbon star]] with a [[Hydrogen-deficient star|hydrogen-deficient]] [[stellar spectrum|spectra]] that also shows evidence of [[s-process]] elements,<ref name=Bond_et_al_1979/> including overabundances of strontium and yttrium, but no barium.<ref name=Malaney1985/> This combination of properties is exceptionally rare; only one other example has been found as of 2012.<ref name=Goswami2012/> The elemental abundances are explained as the result of a single neutron exposure event, which is difficult to reconcile with a conjecture that this may be a post-[[Asymptotic giant branch|AGB]]-type star.<ref name=Malaney1985/> In 1999, U Aqr was proposed to be a [[Thorne-Zytkow object]], instead of being a simple R Coronae Borealis variable.<ref name=Vanture_et_al_1999/> |
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In 1999, U Aqr was proposed to be a [[Thorne-Zytkow object]], instead of being a simple [[R Coronae Borealis variable]].<ref> {{cite journal |title= Is U Aquarii a Thorne-Żytkow Object? |author= Andrew D. Vanture, Daniel Zucker, George Wallerstein |doi= 10.1086/306956 |publicationdate= 1999 April 1 |volume= 514 |number= 2 |journal= The Astrophysical Journal |bibcode= 1999ApJ...514..932V }} </ref> |
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== Notes == |
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{{reflist|group=NB}} |
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==References== |
==References== |
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{{reflist |
{{reflist|refs= |
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<ref name="aavso">{{cite web |title=Download Data |url=https://www.aavso.org/data-download |website=aavso.org |publisher=AAVSO |access-date=1 October 2021}}</ref> |
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<ref name=SIMBAD>{{cite simbad |
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| title=U Aqr | access-date=2021-01-01 }}</ref> |
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<ref name=GaiaDR2>{{Cite Gaia DR2|6826788566384202496}}</ref> |
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<ref name=edr3>{{cite Gaia EDR3|6826788566384202496}}</ref> |
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<ref name=Goswami2012>{{cite conference |
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| title=Spectroscopic characterization of FHLC stars from the Hamburg/ESO survey and a newly found HdC star |
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| last=Goswami | first=Aruna |
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| conference=International Workshop on Stellar Libraries, Proceedings of a conference held 5-9 December, 2011 at University of Delhi, India |
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| editor1-first=Philippe | editor1-last=Prugniel |
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| editor2-first=Harinder P. | editor2-last=Singh |
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| series=Astronomical Society of India Conference Series |
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| volume=6 | date=2012 | page=189 | isbn=978-81-922926-4-9 |
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| arxiv=1204.1806 | bibcode=2012ASInC...6..189G }}</ref> |
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<ref name=Malaney1985>{{cite journal |
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| title=On the nature of the neutron exposure event of U Aquarii |
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| last=Malaney | first=R. A. |
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| journal=Monthly Notices of the Royal Astronomical Society |
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| volume=216 | pages=743–752 | date=October 1985 |
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| issue=3 | bibcode=1985MNRAS.216..743M | doi=10.1093/mnras/216.3.743 | doi-access=free }}</ref> |
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<ref name=Bond_et_al_1979>{{cite journal |
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| title=The extraordinary composition of U Aquarii |
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| display-authors=1 | last1=Bond | first1=H. E. |
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| last2=Luck | first2=R. E. | last3=Newman | first3=M. J. |
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| journal=Astrophysical Journal |
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| volume=233 | pages=205–210 | date=October 1979 |
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| bibcode=1979ApJ...233..205B | doi=10.1086/157382 | doi-access=free }}</ref> |
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<ref name=Lawson_et_al_1990>{{cite journal |
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| title=The photometric characteristics of cool hydrogen-deficient carbon stars. |
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| last1=Lawson | first1=W. A. | last2=Cottrelll | first2=P. L. |
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| last3=Kilmartin | first3=P. M. | last4=Gilmore | first4=A. C. |
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| display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society |
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| volume=247 | page=91 | date=November 1990 |
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| bibcode=1990MNRAS.247...91L }}</ref> |
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<ref name=Samus_et_al_2017>{{cite journal |
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| title=General catalogue of variable stars: Version GCVS 5.1 |
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| last1=Samus' | first1=N. N | last2=Kazarovets | first2=E. V |
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| last3=Durlevich | first3=O. V | last4=Kireeva | first4=N. N |
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| last5=Pastukhova | first5=E. N | journal=Astronomy Reports |
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| volume=61 | issue=1 | pages=80 | year=2017 |
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| bibcode=2017ARep...61...80S | s2cid=125853869 |
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| doi=10.1134/S1063772917010085 }}</ref> |
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<ref name=Vanture_et_al_1999>{{cite journal |
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| title= Is U Aquarii a Thorne-Żytkow Object? |
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| display-authors=1 | first1=Andrew D. | last1=Vanture |
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| first2=Daniel | last2=Zucker | first3=George | last3=Wallerstein |
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| journal=The Astrophysical Journal |
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| date=April 1, 1999 | volume=514 | number=2 | pages=932–938 |
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| bibcode=1999ApJ...514..932V | doi=10.1086/306956 | doi-access=free }}</ref> |
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<ref name=majewski2017>{{cite journal |bibcode=2017AJ....154...94M |title=The Apache Point Observatory Galactic Evolution Experiment (APOGEE) |last1=Majewski |first1=Steven R. |last2=Schiavon |first2=Ricardo P. |last3=Frinchaboy |first3=Peter M. |last4=Allende Prieto |first4=Carlos |last5=Barkhouser |first5=Robert |last6=Bizyaev |first6=Dmitry |last7=Blank |first7=Basil |last8=Brunner |first8=Sophia |last9=Burton |first9=Adam |last10=Carrera |first10=Ricardo |last11=Chojnowski |first11=S. Drew |last12=Cunha |first12=Kátia |last13=Epstein |first13=Courtney |last14=Fitzgerald |first14=Greg |last15=García Pérez |first15=Ana E. |last16=Hearty |first16=Fred R. |last17=Henderson |first17=Chuck |last18=Holtzman |first18=Jon A. |last19=Johnson |first19=Jennifer A. |last20=Lam |first20=Charles R. |last21=Lawler |first21=James E. |last22=Maseman |first22=Paul |last23=Mészáros |first23=Szabolcs |last24=Nelson |first24=Matthew |last25=Nguyen |first25=Duy Coung |last26=Nidever |first26=David L. |last27=Pinsonneault |first27=Marc |last28=Shetrone |first28=Matthew |last29=Smee |first29=Stephen |last30=Smith |first30=Verne V. |journal=The Astronomical Journal |year=2017 |volume=154 |issue=3 |page=94 |doi=10.3847/1538-3881/aa784d |arxiv=1509.05420 |s2cid=119293367 |display-authors=29 |doi-access=free }}</ref> |
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<ref name=starhorse>{{cite journal |bibcode=2019A&A...628A..94A |title=Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 |last1=Anders |first1=F. |last2=Khalatyan |first2=A. |last3=Chiappini |first3=C. |last4=Queiroz |first4=A. B. |last5=Santiago |first5=B. X. |last6=Jordi |first6=C. |last7=Girardi |first7=L. |last8=Brown |first8=A. G. A. |last9=Matijevič |first9=G. |last10=Monari |first10=G. |last11=Cantat-Gaudin |first11=T. |last12=Weiler |first12=M. |last13=Khan |first13=S. |last14=Miglio |first14=A. |last15=Carrillo |first15=I. |last16=Romero-Gómez |first16=M. |last17=Minchev |first17=I. |last18=De Jong |first18=R. S. |last19=Antoja |first19=T. |last20=Ramos |first20=P. |last21=Steinmetz |first21=M. |last22=Enke |first22=H. |journal=Astronomy and Astrophysics |volume=628 |pages=A94 |year=2019 |arxiv=1904.11302 |doi=10.1051/0004-6361/201935765 |s2cid = 131780028}}</ref> |
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}} |
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{{Stars of Aquarius}} |
{{Stars of Aquarius}} |
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{{DEFAULTSORT:U Aquarii}} |
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[[Category:Carbon stars]] |
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[[Category:R Coronae Borealis variables]] |
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[[Category:Aquarius (constellation)]] |
[[Category:Aquarius (constellation)]] |
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[[Category:Durchmusterung objects]] |
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[[Category:Hipparcos objects|108876]] |
[[Category:Hipparcos objects|108876]] |
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[[Category: |
[[Category:Objects with variable star designations|Aquarii, U]] |
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[[Category:Objects named with variable star designations|Aquarii, U]] |
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{{var-star-stub}} |
Latest revision as of 01:45, 28 November 2023
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
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Constellation | Aquarius |
Right ascension | 22h 03m 19.69905s[2] |
Declination | −16° 37′ 35.2811″[2] |
Apparent magnitude (V) | 10.6 to 15.9[3] |
Characteristics | |
Spectral type | C-Hd[4] |
U−B color index | 0.07[5] |
B−V color index | 0.66[5] |
Variable type | R CrB[3] |
Astrometry | |
Radial velocity (Rv) | +89.49±1.54[6] km/s |
Proper motion (μ) | RA: 2.780[2] mas/yr Dec.: −1.907[2] mas/yr |
Parallax (π) | 0.0859 ± 0.0222 mas[2] |
Distance | approx. 38,000 ly (approx. 12,000 pc) |
Details | |
Mass | 4.5[7] M☉ |
Surface gravity (log g) | 2.28[7] cgs |
Temperature | 5,500[5] K |
Metallicity [Fe/H] | −0.99[7] dex |
Rotational velocity (v sin i) | 8.4[8] km/s |
Other designations | |
Database references | |
SIMBAD | data |
U Aquarii, abbreviated U Aqr, is a variable star in the equatorial constellation of Aquarius. It is invisible to the naked eye, having an apparent visual magnitude that ranges from 10.6 down to as low as 15.9.[3] Based on parallax measurements, the distance to this star is approximately 38 kly (12 kpc). In 1990, W. A. Lawson and associates provided a distance estimate of 43 kly (13.2 kpc) based on the assumption of a bolometric magnitude of −5.[5] It appears to lie several kiloparsecs below the galactic plane, and thus may belong to an old stellar population.[4]
The stellar classification of this star is C-Hd,[4] and it is classified as a R Coronae Borealis variable.[3] It is a carbon star with a hydrogen-deficient spectra that also shows evidence of s-process elements,[4] including overabundances of strontium and yttrium, but no barium.[10] This combination of properties is exceptionally rare; only one other example has been found as of 2012.[11] The elemental abundances are explained as the result of a single neutron exposure event, which is difficult to reconcile with a conjecture that this may be a post-AGB-type star.[10] In 1999, U Aqr was proposed to be a Thorne-Zytkow object, instead of being a simple R Coronae Borealis variable.[12]
References[edit]
- ^ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ a b c d Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
- ^ a b c d Bond, H. E.; et al. (October 1979). "The extraordinary composition of U Aquarii". Astrophysical Journal. 233: 205–210. Bibcode:1979ApJ...233..205B. doi:10.1086/157382.
- ^ a b c d Lawson, W. A.; et al. (November 1990). "The photometric characteristics of cool hydrogen-deficient carbon stars". Monthly Notices of the Royal Astronomical Society. 247: 91. Bibcode:1990MNRAS.247...91L.
- ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A.; Matijevič, G.; Monari, G.; Cantat-Gaudin, T.; Weiler, M.; Khan, S.; Miglio, A.; Carrillo, I.; Romero-Gómez, M.; Minchev, I.; De Jong, R. S.; Antoja, T.; Ramos, P.; Steinmetz, M.; Enke, H. (2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy and Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. S2CID 131780028.
- ^ Majewski, Steven R.; Schiavon, Ricardo P.; Frinchaboy, Peter M.; Allende Prieto, Carlos; Barkhouser, Robert; Bizyaev, Dmitry; Blank, Basil; Brunner, Sophia; Burton, Adam; Carrera, Ricardo; Chojnowski, S. Drew; Cunha, Kátia; Epstein, Courtney; Fitzgerald, Greg; García Pérez, Ana E.; Hearty, Fred R.; Henderson, Chuck; Holtzman, Jon A.; Johnson, Jennifer A.; Lam, Charles R.; Lawler, James E.; Maseman, Paul; Mészáros, Szabolcs; Nelson, Matthew; Nguyen, Duy Coung; Nidever, David L.; Pinsonneault, Marc; Shetrone, Matthew; Smee, Stephen; et al. (2017). "The Apache Point Observatory Galactic Evolution Experiment (APOGEE)". The Astronomical Journal. 154 (3): 94. arXiv:1509.05420. Bibcode:2017AJ....154...94M. doi:10.3847/1538-3881/aa784d. S2CID 119293367.
- ^ "U Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-01.
- ^ a b Malaney, R. A. (October 1985). "On the nature of the neutron exposure event of U Aquarii". Monthly Notices of the Royal Astronomical Society. 216 (3): 743–752. Bibcode:1985MNRAS.216..743M. doi:10.1093/mnras/216.3.743.
- ^ Goswami, Aruna (2012). Prugniel, Philippe; Singh, Harinder P. (eds.). Spectroscopic characterization of FHLC stars from the Hamburg/ESO survey and a newly found HdC star. International Workshop on Stellar Libraries, Proceedings of a conference held 5-9 December, 2011 at University of Delhi, India. Astronomical Society of India Conference Series. Vol. 6. p. 189. arXiv:1204.1806. Bibcode:2012ASInC...6..189G. ISBN 978-81-922926-4-9.
- ^ Vanture, Andrew D.; et al. (April 1, 1999). "Is U Aquarii a Thorne-Żytkow Object?". The Astrophysical Journal. 514 (2): 932–938. Bibcode:1999ApJ...514..932V. doi:10.1086/306956.