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TW Piscis Austrini

Fomalhaut
Heic0821f.jpg
DSS image of Fomalhaut, field of view 2.7×2.9 degrees.
Credit NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)
Observation data
Epoch J2000      Equinox J2000
Constellation Piscis Austrinus (Fomalhaut A+B), Aquarius (Fomalhaut C)
Fomalhaut
Right ascension 22h 57m 39.0465s
Declination −29° 37′ 20.050″
Apparent magnitude (V) 1.16
TW Piscis Austrini
Right ascension 22h 56m 24.05327s
Declination −31° 33′ 56.0351″
Apparent magnitude (V) 6.48
LP 876-10
Right ascension 22h 48m 04.47s
Declination −24° 22′ 07.5″
Apparent magnitude (V) 12.618
Characteristics
Spectral type A3 V / K5Vp / M4V
U−B color index 0.08 / 1.02 / ?
B−V color index 0.09 / 1.10 / 1.683
Variable type None / BY Draconis / ?
Astrometry
Fomalhaut
Radial velocity (Rv) +6.5 km/s
Proper motion (μ) RA: +328.95 mas/yr
Dec.: −164.67 mas/yr
Parallax (π) 129.81 ± 0.47mas
Distance 25.13 ± 0.09 ly
(7.70 ± 0.03 pc)
Absolute magnitude (MV) 1.72
TW Piscis Austrini
Radial velocity (Rv) +6 km/s
Proper motion (μ) RA: −331.11 mas/yr
Dec.: −158.98 mas/yr
Parallax (π) 131.42 ± 0.62mas
Distance 24.8 ± 0.1 ly
(7.61 ± 0.04 pc)
Absolute magnitude (MV) 7.08
Details
Fomalhaut
Mass 1.92±0.02 M
Radius 1.842±0.019 R
Luminosity 16.63±0.48 L
Surface gravity (log g) 4.21 cgs
Temperature 8,590 K
Metallicity [Fe/H] −0.03 to −0.34 dex
Rotational velocity (v sin i) 93 km/s
Age (4.4±0.4)×108 years
TW Piscis Austrini
Mass 0.725 ± 0.036 M
Radius 0.629 ± 0.051 R
Luminosity 0.19 L
Temperature 4,711 ± 134 K
Rotational velocity (v sin i) 2.93 km/s
Age 4.4 × 108 years
Other designations
Fomalhaut: α Piscis Austrini, α PsA, Alpha PsA, 24 Piscis Austrini, CPD −30° 6685, FK5 867, Gl 881, HD 216956, HIP 113368, HR 8728, SAO 191524
TW Piscis Austrini: Fomalhaut B, TW PsA, Gl 879, HR 8721, CD -32°17321, HD 216803, LTT 9283, GCTP 5562.00, SAO 214197, CP(D)-32 6550, HIP 113283
LP 876-10: Fomalhaut C, 2MASS J22480446-2422075, NLTT 54872, GSC 06964-01226
Database references
SIMBAD AC
AB
A (Fomalhaut)
B (TW PsA)
C (LP 876-10)
planet b
Exoplanet Archive data
ARICNS A (Fomalhaut)
B (TW PsA)
Extrasolar Planets
Encyclopaedia
data

Fomalhaut, also designated Alpha Piscis Austrini (α Piscis Austrini, abbreviated Alpha PsA, α PsA) is the brightest star in the constellation of Piscis Austrinus and one of the brightest stars in the sky. It 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. It is classified as a Vega-like star that emits excess infrared radiation, indicating it is surrounded by a circumstellar disk. Fomalhaut, K-type main-sequence star TW Piscis Austrini, and M-type, red dwarf star LP 876-10 constitute a triple system, even though the companions are separated by several degrees.

Fomalhaut holds a special significance in extrasolar planet research, as it is the center of the first stellar system with an extrasolar planet candidate (designated Fomalhaut b, later named Dagon) imaged at visible wavelengths. The image was published in Science in November 2008. Fomalhaut is the third brightest star (as viewed from Earth) known to have a planetary system, after the Sun and Pollux.


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Wikipedia

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