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 [6]
Mass 0.704±0.016  M☉
Radius 0.658±0.009  R☉
Luminosity 0.19 [5]   L☉
Temperature 4,610±67  K
Metallicity [Fe/H]−0.07±0.03  dex
Rotation 10.3 [7] 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 [8]
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. [9]

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. [11] 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. [9]

Planetary system

In 2019, an exoplanet candidate around Fomalhaut B was detected by astrometry, but this remains unconfirmed. [12] [13]

The Fomalhaut B planetary system [13]
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

<span class="mw-page-title-main">Piscis Austrinus</span> Constellation in the southern celestial hemisphere

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.

<span class="mw-page-title-main">Fomalhaut</span> Triple star system in the constellation Piscis Austrinus

Fomalhaut is the brightest star in the southern constellation of Piscis Austrinus, the Southern Fish, and one of the brightest stars in the night sky. It has the Bayer designation Alpha Piscis Austrini, which is an alternative form of α Piscis Austrini, and is abbreviated Alpha PsA or α PsA. This is a class A star on the main sequence approximately 25 light-years (7.7 pc) from the Sun as measured by the Hipparcos astrometry satellite. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.

<span class="mw-page-title-main">63 Andromedae</span> Star in the constellation Andromeda

63 Andromedae is an Alpha2 Canum Venaticorum variable star in the constellation Andromeda. Its variable star designation is PZ Andromedae. With an apparent magnitude of about 5.6, it is bright enough to be seen by naked eye. Based upon an annual parallax shift of 8.53 mas, it is located 382 light years away.

<span class="mw-page-title-main">Chi Draconis</span> Star in the constellation of Draco

Chi Draconis is a magnitude 3.6 binary star in the constellation Draco. It also has the Flamsteed designation 44 Draconis. At a distance of 27 light years, it is one of the forty or so closest stars.

<span class="mw-page-title-main">NO Aurigae</span> Star in the constellation Auriga

NO Aurigae is a pulsating variable star in the constellation Auriga. It is an unusually-luminous asymptotic giant branch star about 3,500 light years away.

<span class="mw-page-title-main">HD 123657</span> Star in the constellation Boötes

HD 123657, or BY Boötis, is a variable star of magnitude 4.98–5.33V. This makes it a dim naked eye star. The star is located near the end of the handle of the Big Dipper, but just within the boundaries of the constellation Boötes.

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

W Andromedae is a variable star in the constellation of Andromeda. It is classified as a Mira variable and S-type star, and varies from an apparent visual magnitude of 14.6 at minimum brightness to a magnitude of 6.7 at maximum brightness, with a period of approximately 397.3 days. The star is losing mass due to stellar winds at a rate of 2.79×10−7M☉/yr.

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

V429 Geminorum (BD+20°1790) is a young orange dwarf star in the constellation Gemini, located 90 light years away from the Sun. It is a BY Draconis variable, a cool dwarf which varies rapidly in brightness as it rotates.

<span class="mw-page-title-main">1 Camelopardalis</span> Double star system in the constellation Camelopardalis

1 Camelopardalis is a double star system in the constellation Camelopardalis. Its combined apparent magnitude is 5.56 and it is approximately 800 parsecs (2,600 ly) away.

<span class="mw-page-title-main">R Equulei</span> Variable star in the constellation of Equuleus

R Equulei is a class M Mira variable star in the constellation Equuleus. Its brightness varies between a minimum magnitude of 15.0 to a maximum of 8.7 with an average period of 261 days.

<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.

<span class="mw-page-title-main">Delta Coronae Borealis</span> Yellow giant star in the constellation Corona Borealis

Delta Coronae Borealis, Latinized from δ Coronae Borealis, is a variable star in the constellation Corona Borealis. Its apparent magnitude varies regularly between apparent magnitude 4.57 and 4.69, and it is around 170 light-years distant.

<span class="mw-page-title-main">28 Monocerotis</span> Star in the constellation Monoceros

28 Monocerotis is a single star in the equatorial constellation of Monoceros. It has an orange-hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.69. The distance to this star is approximately 450 light years based on parallax, and it has an absolute magnitude of −1.00. The star is drifting further away from the Sun with a radial velocity of +26.7 km/s.

<span class="mw-page-title-main">Sigma Ophiuchi</span> Star in the constellation Ophiuchus

Sigma Ophiuchi, Latinized from σ Ophiuchi, is a single, orange-hued star in the equatorial constellation Ophiuchus. Its apparent visual magnitude is 4.31, which is bright enough to be faintly visible to the naked eye. The annual parallax shift of 3.62 mas as seen from Earth provides a distance estimate of roughly 900 light years. It is moving closer to the Sun with a radial velocity of −28 km/s.

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

Y Centauri or Y Cen is a semiregular variable star in the constellation of Centaurus.

<span class="mw-page-title-main">10 Persei</span> Blue supergiant star in the constellation Perseus

10 Persei is a blue supergiant star in the constellation Perseus. Its apparent magnitude is 6.26 although it is slightly variable.

<span class="mw-page-title-main">Gliese 908</span> Star in the constellation Pisces

Gliese 908 is a red dwarf star, located in constellation Pisces at 19.3 light-years from Earth. It is a BY Draconis variable star with a variable star designation of BR Piscium. Its apparent magnitude varies between magnitude 8.93 and magnitude 9.03 as a result of starspots and varying chromospheric activity.

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

Gliese 402 is a star located 22.7 light years from the Solar System. Located in the constellation of Leo, it is also known as Wolf 358 from its entry in Max Wolf's star catalogue. The stars nearest to Gliese 402 are Gliese 393, at 3.43 light years, Gliese 408, at 6.26 light years, and Gliese 382 at 6.66 light years.

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

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<span class="mw-page-title-main">HD 150193</span> Young binary star system in the constellation Ophiuchus

HD 150193 is a binary star system in the constellation of Ophiuchus. The primary star was identified as a Herbig Ae/Be star with a strong solar wind, losing approximately a tenth of solar mass per million years. It does host a very small debris disk, likely due to disk truncation by the nearby stellar companion. The disk is inclined 38±9° to the plane of sky. It appears to be highly evolved and asymmetric, with indications of flattening and grains growth.

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 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. ↑ Gomes da Silva, J.; Santos, N. C.; Adibekyan, V.; Sousa, S. G.; Campante, T. L.; Figueira, P.; Bossini, D.; Delgado-Mena, E.; Monteiro, M. J. P. F. G.; de Laverny, P.; Recio-Blanco, A.; Lovis, C. (2021-02-01). "Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample. I. A catalogue of homogeneous chromospheric activity". Astronomy and Astrophysics. 646: A77. arXiv: 2012.10199 . doi:10.1051/0004-6361/202039765. ISSN   0004-6361. Fomalhaut B's database entry at VizieR.
  7. ↑ 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.
  8. ↑ "V* TW PsA -- Variable of BY Dra type". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-01-20.
  9. 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.
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ 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.
  13. 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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