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Theta Coronae Australis

θ Coronae Australis
Location of Theta CrA (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Corona Australis
Right ascension 18h 33m 30.18577s[1]
Declination −42° 18′ 45.0297″[1]
Apparent magnitude (V) 4.61±0.01[2]
Characteristics
Spectral type G8 III[3]
U−B color index +0.76[4]
B−V color index +1.02[4]
Astrometry
Radial velocity (Rv)−2.1±2.8[5] km/s
Proper motion (μ) RA: +32.046 mas/yr[1]
Dec.: −20.932 mas/yr[1]
Parallax (π)6.1673 ± 0.1535 mas
Distance530 ± 10 ly
(162 ± 4 pc)
Absolute magnitude (MV)−1.54[6]
Details
Mass4.45±0.22[7] M☉
Radius29.1±1.5[8] R☉
Luminosity411+21
−19[1] L☉
Surface gravity (log g)2.50[9] cgs
Temperature4,907±59[10] K
Metallicity [Fe/H]+0.00[1] dex
Rotational velocity (v sin i)12±1[11] km/s
Other designations
15 G. Coronae Australis[12], CD−42°13378, CPD−42°8423, FK5 697, GC 25313, HD 170845, HIP 90982, HR 6951, SAO 229111[13]
Database references
SIMBADdata

Theta Coronae Australis (Theta CrA), Latinized from θ Coronae Australis, is a solitary yellow-hued star[14] located in the southernconstellation Corona Australis. It has an apparent magnitude of 4.61, making it readily visible to the naked eye. Gaia DR3 parallax measurements place it 530 light years away and it is currently drifting closer with a somewhat constrained heliocentric radial velocity of −2.1 km/s. At its current distance, Theta CrA's brightness is diminished by three-tenths of a magnitudes due to interstellar dust.[15] It has an absolute magnitude of −1.54.[6]

This is an evolved red giant with a stellar classification of G8 III.[3] It has 4.45 times the mass of the Sun[7] but has expanded to 29.1 times the solar radius.[8] It radiates 411 times the luminosity of the Sun[1] from its enlarged photosphere at an effective temperature of 4,907 K.[10] Theta CrA has a solar metallicity;[1] unlike most giant stars of this type, Theta CrA has an unusually high rate of rotation with a projected rotational velocity of 12 km/s.[11] The star may also have infrared excess, suggesting the presence of a circumstellar disk.[16] One possible explanation is that it may have engulfed a nearby giant planet, such as a hot Jupiter.[16]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Tycho2000 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1978 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Kervella2021 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Kervella2004 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Lafrasse2010 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Blackwell1998 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference De Medeiros2014 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Gontcharov2017 was invoked but never defined (see the help page).
  16. ^ a b Cite error: The named reference da Silva2015 was invoked but never defined (see the help page).
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