TW Piscis Austrini

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TW Piscis Austrini
Piscis Austrinus constellation map.svg
Red circle.svg
Location of TW Piscis Austrini (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Piscis Austrinus
Right ascension 22h 56m 24.05256s [1]
Declination −31° 33′ 56.0306″ [1]
Apparent magnitude  (V)5.44–6.51 [2]
Characteristics
Spectral type K5Vp [3]
U−B color index 1.02 [4]
B−V color index 1.10 [4]
Variable type BY Draconis [2]
Astrometry
Radial velocity (Rv)+6.79±0.12 [1]  km/s
Proper motion (μ)RA: 330.203  mas/yr [1]
Dec.: −158.602  mas/yr [1]
Parallax (π)131.5525 ± 0.0275  mas [1]
Distance 24.793 ± 0.005  ly
(7.602 ± 0.002  pc)
Absolute magnitude  (MV)7.08 [5]
Details
Mass 0.725 ± 0.036 [3]   M☉
Radius 0.629 ± 0.051 [3]   R☉
Luminosity 0.19 [5]   L☉
Temperature 4,711 ± 134 [3]   K
Rotation 10.3 [6] days
Rotational velocity (v sin i)2.93 [3]  km/s
Age 440 [5]   Myr
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 [7]
Database references
SIMBAD data
ARICNS data

TW Piscis Austrini (also known as Fomalhaut B) is a main sequence star in the constellation Piscis Austrinus. It lies relatively close to the Sun, at an estimated distance of 24.8 light-years (7.6 parsecs ). To an observer on Earth the star is visually separated from its larger companion Fomalhaut (A) by 2 degrees—the width of four full moons. [8]

Contents

A visual band light curve for TW Piscis Austrini, adapted from Busko and Torres (1978). The error bar shown on the left-most point applies to all points. TWPsALightCurve.png
A visual band light curve for TW Piscis Austrini, adapted from Busko and Torres (1978). The error bar shown on the left-most point applies to all points.

The name TW Piscis Austrini is a variable star designation. This is a variable star of the type known as a BY Draconis variable, with surface brightness variations causing the changes as the star rotates. It varies slightly in apparent magnitude, ranging from 6.44 to 6.51 over a 10.3-day period. [2]

TW Piscis Austrini lies within a light-year of Fomalhaut. [10] Due to sharing the same proper motion, and the same estimated age of approximately 440 ± 40 million years, astronomers now consider them to be elements of a multiple star system. [5] A third star, dimmer and more widely separated, Fomalhaut C, gives the system the widest visual separation, to observers from Earth, at approximately 6 degrees. [8]

Planetary system

In 2019, an exoplanet candidate around Fomalhaut B was detected by astrometry, but this remains unconfirmed. [11] [12]

The Fomalhaut B planetary system [12]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(years)		 Eccentricity Inclination Radius
b(unconfirmed)1.2+0.7
−0.6 MJ 		—25+52
−21		———

Related Research Articles

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Piscis Austrinus is a constellation in the southern celestial hemisphere. The name is Latin for "the southern fish", in contrast with the larger constellation Pisces, which represents a pair of fish. Before the 20th century, it was also known as Piscis Notius. Piscis Austrinus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. The stars of the modern constellation Grus once formed the "tail" of Piscis Austrinus. In 1597, Petrus Plancius carved out a separate constellation and named it after the crane.

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<span class="mw-page-title-main">W Andromedae</span> Variable star in the constellation Andromeda

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<span class="mw-page-title-main">V429 Geminorum</span> Star in the constellation Gemini

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<span class="mw-page-title-main">Eta Piscis Austrini</span> Star in the constellation Piscis Austrinus

Eta Piscis Austrini is binary star system in the southern constellation of Piscis Austrinus. As of 2000, the two components had an angular separation of 1.818 arc seconds along a position angle of 113.4°. The pair have a combined apparent visual magnitude of +5.43, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 3.99 mas as seen from the Earth, the system is located roughly 820 light years from the Sun.

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<span class="mw-page-title-main">Gliese 402</span> Star in the constellation Leo

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<span class="mw-page-title-main">V Antliae</span> Star in the constellation Antlia

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<span class="mw-page-title-main">8 Draconis</span> White-hued chemically unusual star in the constellation Draco

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<span class="mw-page-title-main">T Leporis</span> Star in the constellation Lepus

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<span class="mw-page-title-main">Y Tauri</span> Variable star in the constellation Scutum

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References

  1. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  3. 1 2 3 4 5 Demory, Brice-Olivier; Ségransan, Damien; Forveille, Thierry; Queloz, Didier; Beuzit, Jean-Luc; Delfosse, Xavier; Di Folco, Emmanuel; Kervella, Pierre; Le Bouquin, Jean-Baptiste; Perrier, Christian; Benisty, Myriam; Duvert, Gilles; Hofmann, Karl-Heinz; Lopez, Bruno; Petrov, Romain (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. S2CID   14786643.
  4. 1 2 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99): 99. Bibcode:1966CoLPL...4...99J.
  5. 1 2 3 4 Mamajek, E.E. (August 2012). "On the Age and Binarity of Fomalhaut". Astrophysical Journal Letters. 754 (2): L20. arXiv: 1206.6353 . Bibcode:2012ApJ...754L..20M. doi:10.1088/2041-8205/754/2/L20. S2CID   119191190.
  6. ↑ Mamajek, Eric E.; et al. (2013). "The Solar Neighborhood. XXX. Fomalhaut C". The Astronomical Journal. 146 (6): 154–163. arXiv: 1310.0764 . Bibcode:2013AJ....146..154M. doi:10.1088/0004-6256/146/6/154. S2CID   67821813.
  7. ↑ "V* TW PsA -- Variable of BY Dra type". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-01-20.
  8. 1 2 Bob King (2014-10-01). "Fomalhaut: A crazy-wide triple stat". Sky & Telescope . Retrieved 2020-06-13. Though it may appear isolated in the barren October sky, Fomalhaut has company. It feels the gravitational tug of the magnitude +6.5 star TW Piscis Austrini, 2° to the south. Both are 25 light-years distant and move in tandem across space, partaking of the same proper motion. They form a true double star with an actual separation of 5.5 trillion miles, or 0.91 light-year.
  9. ↑ Busko, I. C.; Torres, C. A. O. (March 1978). "Flare activity by BY Draconis stars". Astronomy and Astrophysics. 64: 153–160. Bibcode:1978A&A....64..153B . Retrieved 23 February 2022.
  10. ↑ Fred Schaaf (31 March 2008). The Brightest Stars: Discovering the Universe through the Sky's Most Brilliant Stars. Wiley. ISBN   978-0-470-24917-8.
  11. ↑ Joe Rao (2019-09-23). "Fomalhaut, 'Royal' Star of Autumn, Swims with the Southern Fish". Space.com . 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.
  12. 1 2 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 . 158 (6): 225. arXiv: 1910.02965 . Bibcode:2019AJ....158..225D. doi:10.3847/1538-3881/ab4c9b. S2CID   203902656.
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