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{{Redirect|Fomalhaut B|the extrasolar planet candidate|Fomalhaut b}}
#REDIRECT [[Fomalhaut#Fomalhaut B (TW Piscis Austrini)]]
{{Starbox begin
| name=TW Piscis Austrini }}
{{Starbox observe
| epoch=J2000
| ra={{RA|22|56|24.05327}}<ref name=aaa474_2_653/>
| dec={{DEC|−31|33|56.0351}}<ref name=aaa474_2_653/>
| appmag_v=6.48<ref name="SIMBAD">{{cite web
| title=V* TW PsA -- Variable of BY Dra type | work=SIMBAD
| publisher=Centre de Données astronomiques de Strasbourg
| url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GJ+879&submit=SIMBAD+search
| accessdate=2010-01-20 }}</ref>
| constell=[[Piscis Austrinus]] }}
{{Starbox character
| class=K5Vp<ref name=aaa505_1_205/>
| b-v=1.10<ref name="clpl4">{{cite journal
| author=Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z.
| title=UBVRIJKL photometry of the bright stars
| journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | year=1966
| bibcode=1966CoLPL...4...99J }}</ref>
| u-b=1.02<ref name="clpl4" />
| variable=[[BY Draconis variable|BY Draconis]] }}
{{Starbox astrometry
| radial_v=+6<ref name="SIMBAD" />
| prop_mo_ra=−331.11<ref name=aaa474_2_653/>
| prop_mo_dec=−158.98<ref name=aaa474_2_653/>
| parallax=131.42
| p_error=0.62
| parallax_footnote=<ref name=aaa474_2_653/>
| absmag_v=7.08<ref name="age_mam"/> }}
{{Starbox detail
| mass={{nowrap|0.725 ± 0.036}}<ref name=aaa505_1_205/>
| radius={{nowrap|0.629 ± 0.051}}<ref name=aaa505_1_205 />
| luminosity=0.19<ref name="age_mam"/>
| temperature={{nowrap|4,711 ± 134}}<ref name=aaa505_1_205/>
| metal=
| rotation=
| rotational_velocity=2.93<ref name=aaa505_1_205/>
| age=4.4 × 10<sup>8</sup><ref name="age_mam"/> }}
{{Starbox catalog
| names=TW PsA, [[Henry L. Giclas catalogue|Gl]] 879, [[Harvard Revised catalogue|HR]] 8721, [[Cordoba Durchmusterung|CD]] -32°17321, [[Henry Draper catalogue|HD]] 216803, [[Luyten Two-Tenths catalogue|LTT]] 9283, [[General Catalogue of Trigonometric Parallaxes|GCTP]] 5562.00, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 214197, CP(D)-32 6550, [[Hipparcos catalogue|HIP]] 113283. }}
{{Starbox reference
| Simbad = HD+216803
| NSTED = <!--Exoplanet Archive name-->
| ARICNS = 01875
| EPE = <!--Name-->
}}
{{Starbox end}}
'''TW Piscis Austrini''' (also Fomalhaut B) is a dwarf [[star]] in the [[constellation]] [[Piscis Austrinus]]. It lies relatively close to the [[Sun]], at an estimated distance of 24.9 [[light year]]s.


The TW in the name is astronomical nomenclature for a [[variable star]]. This is a [[flare star]] of the type known as a [[BY Draconis variable]]. It varies slightly in [[apparent magnitude]], ranging from 6.44 to 6.49 over a 10.3 day period. While smaller than the [[Sun]], it is relatively large for a flare star. Most flare stars are red [[stellar classification|M-type]] dwarfs.
{{Redirect category shell|1=

{{R from merge}}
TW Piscis Austrini lies within a [[light year]] of the much brighter star [[Fomalhaut]],<ref>p. 237, ''The Brightest Stars: Discovering The Universe Through The Sky's Most Brilliant Stars'', Fred Schaaf, Hoboken, NJ: John Wiley & Sons, Inc., 2008, ISBN 978-0-471-70410-2.</ref> and the two may be travelling companions that share a common motion through space.
{{R to section}}

A 2012 study<ref name="age_mam"/> showed that TW PsA and [[Fomalhaut]] are approximately only 0.28 parsecs (57,000 AU) apart, and share a space velocity within 0.1±0.5&nbsp;km/s, consistent with constituting a physical binary system. Independent age estimates for [[Fomalhaut]] and TW PsA yield similar results, and the age for the system is 440±40 million years.<ref name="age_mam"/>

In 2019 NASA's [[Transiting Exoplanet Survey Satellite]] space telescope found a exoplanet candidate around Fomalhaut B.<ref name=space2019-09-23/><ref name=AstronomicalJournal2019-10-07/>

== References ==
{{reflist|refs=

<ref name=age_mam>{{Cite journal | last1=Mamajek | first1=E.E. | title=On the Age and Binarity of Fomalhaut | journal=Astrophysical Journal Letters | volume=754 | issue=2 |date=August 2012 | pages=L20 | doi=10.1088/2041-8205/754/2/L20 | bibcode=2012ApJL..754...20M | arxiv=1206.6353}}</ref>

<ref name=aaa474_2_653>{{citation | last1=van Leeuwen | first1=F. | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 |date=November 2007 | pages=653–664 | doi=10.1051/0004-6361:20078357 | bibcode=2007A&A...474..653V | arxiv=0708.1752 }}</ref>

<ref name=aaa505_1_205>{{citation | display-authors=1 | last1=Demory | first1=B.-O. | last2=Ségransan | first2=D. | last3=Forveille | first3=T. | last4=Queloz | first4=D. | last5=Beuzit | first5=J.-L. | last6=Delfosse | first6=X. | last7=di Folco | first7=E. | last8=Kervella | first8=P. | last9=Le Bouquin | first9=J.-B. |date=October 2009 | title=Mass-radius relation of low and very low-mass stars revisited with the VLTI | journal=Astronomy and Astrophysics | volume=505 | issue=1 | pages=205–215 | doi=10.1051/0004-6361/200911976 | bibcode=2009A&A...505..205D |arxiv = 0906.0602 }}</ref>

<ref name=space2019-09-23>
{{cite news
| url = https://www.space.com/fomalhaut-autumn-star-skywatching.html
| title = Fomalhaut, 'Royal' Star of Autumn, Swims with the Southern Fish
| work = [[Space magazine]]
| author = Joe Rao
| date = 2019-09-23
| archiveurl =
| archivedate =
| accessdate = 2020-06-13
| url-status = live
| quote = Believe it or not, an extrasolar planet might also be circling TW Piscis Austrini. NASA's Transiting Exoplanet Survey Satellite (TESS), a space telescope that's searching for planets around the brightest stars in Earth's night sky, recently found a possible candidate circling this star. It's almost the same size as our Earth, and orbits the star about every 10 days at a distance of 7.5 million miles from it.
}}
}}
</ref>

<ref name=AstronomicalJournal2019-10-07>
{{cite journal
| url = https://arxiver.moonhats.com/2019/10/09/the-possible-astrometric-signature-of-a-planetary-mass-companion-to-the-nearby-young-star-tw-piscis-austrini-fomalhaut-b-constraints-from-astrometry-radial-velocities-and-direct-imaging-epa/
|title = The Possible Astrometric Signature of a Planetary-mass Companion to the Nearby Young Star TW Piscis Austrini (Fomalhaut B): Constraints from Astrometry, Radial Velocities, and Direct Imaging
| journal = [[Astronomical Journal]]
| last1 = De Rosa
| first1 = Robert J.
| last2 = Esposito
| first2 = Thomas M.
| last3 = Hirsch
| first3 = Lea A.
| last4 = Nielsen
| first4 = Eric L.
| last5 = Marley
| first5 = Mark S.
| last6 = Kalas
| first6 = Paul
| last7 = Wang
| first7 = Jason J.
| last8 = Macintosh
| first8 = Bruce
| date = 7 October 2019
| eprint = 1910.02965
<!-- | class = astro-ph.EP -->
}}
</ref>
}}

== External links ==
* [http://www.solstation.com/stars/tw-psa.htm TW Piscis Austrini] at SolStation.
{{Nearest star systems|6}}
{{Stars of Piscis Austrinus}}

[[Category:Piscis Austrinus]]
[[Category:K-type main-sequence stars]]
[[Category:BY Draconis variables]]
[[Category:Objects within 100 ly of Earth]]
[[Category:Objects named with variable star designations|Piscis Austrini, TW]]
[[Category:Henry Draper Catalogue objects|216803]]

Revision as of 02:34, 16 June 2020

"Fomalhaut B" redirects here. For the extrasolar planet candidate, see Fomalhaut b.
TW Piscis Austrini
Observation data
Epoch J2000      Equinox J2000
Constellation Piscis Austrinus
Right ascension 22h 56m 24.05327s[1]
Declination −31° 33′ 56.0351″[1]
Apparent magnitude (V) 6.48[2]
Characteristics
Spectral type K5Vp[3]
U−B color index 1.02[4]
B−V color index 1.10[4]
Variable type BY Draconis
Astrometry
Radial velocity (Rv)+6[2] km/s
Proper motion (μ) RA: −331.11[1] mas/yr
Dec.: −158.98[1] mas/yr
Parallax (π)131.42 ± 0.62 mas[1]
Distance24.8 ± 0.1 ly
(7.61 ± 0.04 pc)
Absolute magnitude (MV)7.08[5]
Details
Mass0.725 ± 0.036[3] M☉
Radius0.629 ± 0.051[3] R☉
Luminosity0.19[5] L☉
Temperature4,711 ± 134[3] K
Rotational velocity (v sin i)2.93[3] km/s
Age4.4 × 108[5] years
Other designations
TW PsA, Gl 879, HR 8721, CD -32°17321, HD 216803, LTT 9283, GCTP 5562.00, SAO 214197, CP(D)-32 6550, HIP 113283.
Database references
SIMBADdata
ARICNSdata

TW Piscis Austrini (also Fomalhaut B) is a dwarf star in the constellation Piscis Austrinus. It lies relatively close to the Sun, at an estimated distance of 24.9 light years.

The TW in the name is astronomical nomenclature for a variable star. This is a flare star of the type known as a BY Draconis variable. It varies slightly in apparent magnitude, ranging from 6.44 to 6.49 over a 10.3 day period. While smaller than the Sun, it is relatively large for a flare star. Most flare stars are red M-type dwarfs.

TW Piscis Austrini lies within a light year of the much brighter star Fomalhaut,[6] and the two may be travelling companions that share a common motion through space.

A 2012 study[5] showed that TW PsA and Fomalhaut are approximately only 0.28 parsecs (57,000 AU) apart, and share a space velocity within 0.1±0.5 km/s, consistent with constituting a physical binary system. Independent age estimates for Fomalhaut and TW PsA yield similar results, and the age for the system is 440±40 million years.[5]

In 2019 NASA's Transiting Exoplanet Survey Satellite space telescope found a exoplanet candidate around Fomalhaut B.[7][8]

References

  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
  2. ^ a b "V* TW PsA -- Variable of BY Dra type". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-01-20.
  3. ^ a b c d e Demory, B.-O.; et al. (October 2009), "Mass-radius relation of low and very low-mass stars revisited with the VLTI", Astronomy and Astrophysics, 505 (1): 205–215, arXiv:0906.0602, Bibcode:2009A&A...505..205D, doi:10.1051/0004-6361/200911976
  4. ^ a b Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ a b c d e Mamajek, E.E. (August 2012). "On the Age and Binarity of Fomalhaut". Astrophysical Journal Letters. 754 (2): L20. arXiv:1206.6353. Bibcode:2012ApJL..754...20M. doi:10.1088/2041-8205/754/2/L20.
  6. ^ p. 237, The Brightest Stars: Discovering The Universe Through The Sky's Most Brilliant Stars, Fred Schaaf, Hoboken, NJ: John Wiley & Sons, Inc., 2008, ISBN 978-0-471-70410-2.
  7. ^ Joe Rao (2019-09-23). "Fomalhaut, 'Royal' Star of Autumn, Swims with the Southern Fish". Space magazine. Retrieved 2020-06-13. Believe it or not, an extrasolar planet might also be circling TW Piscis Austrini. NASA's Transiting Exoplanet Survey Satellite (TESS), a space telescope that's searching for planets around the brightest stars in Earth's night sky, recently found a possible candidate circling this star. It's almost the same size as our Earth, and orbits the star about every 10 days at a distance of 7.5 million miles from it.{{cite news}}: CS1 maint: url-status (link)
  8. ^ De Rosa, Robert J.; Esposito, Thomas M.; Hirsch, Lea A.; Nielsen, Eric L.; Marley, Mark S.; Kalas, Paul; Wang, Jason J.; Macintosh, Bruce (7 October 2019). "The Possible Astrometric Signature of a Planetary-mass Companion to the Nearby Young Star TW Piscis Austrini (Fomalhaut B): Constraints from Astrometry, Radial Velocities, and Direct Imaging". Astronomical Journal. arXiv:1910.02965.
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