Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Telescopium |
Right ascension | 19h 50m 14.05959s[2] |
Declination | −47° 33′ 26.6014″[2] |
Apparent magnitude (V) | 5.95 - 6.07[3] |
Characteristics | |
Evolutionary stage | AGB[4] |
Spectral type | M1 III[5] |
B−V color index | +1.67[6] |
Variable type | suspected[3] |
Astrometry | |
Radial velocity (Rv) | −64±1[7] km/s |
Proper motion (μ) | RA: +9.424 mas/yr[2] Dec.: −10.867 mas/yr[2] |
Parallax (π) | 3.1998 ± 0.0655 mas[2] |
Distance | 1,020 ± 20 ly (313 ± 6 pc) |
Absolute magnitude (MV) | −0.80[8] |
Details | |
Mass | 1.76±0.09[9] M☉ |
Radius | 111±6[10] R☉ |
Luminosity | 1,031±56[11] L☉ |
Surface gravity (log g) | 1.5±1[2] cgs |
Temperature | 3,821±122[12] K |
Metallicity [Fe/H] | +0.24[2] dex |
Other designations | |
Database references | |
SIMBAD | data |
HD 187086, also known as HR 7537, is a probable astrometric binary[15] (87% chance[16]) located in the southern constellation Telescopium. It has an average apparent magnitude of 5.9, making it faintly visible to the naked eye. The star is located relatively far at a distance of 1,020 light years based on Gaia DR3 parallax measurements[2] but is rapidly drifting closer with a heliocentric radial velocity of −64 km/s.[7] At its current distance, HD 187086's brightness is diminished by 0.27 magnitudes due to interstellar dust.[17] It has an absolute magnitude of −0.8.[8]
The primary has a stellar classification of M1 III,[5] indicating that it is a red giant. It is currently on the asymptotic giant branch, fusing hydrogen and helium shells around an inert carbon core. It has 1.76 times the mass of the Sun[9] but it has expanded to 111 times the solar radius.[10] It radiates 1,031 times the luminosity of the Sun[11] from its enlarged photosphere at an effective temperature of 3,821 K,[12] giving it a red hue. HD 187086 is particularly metal enriched ([Fe/H] = +0.24).[2]
HD 187086 fluctuates between 5.95 and 6.07[3] and its variability was first noticed by P.M. Corben in 1971 after being listed as an ordinary M-type giant a year prior.[6][18] In 2002, Chris Koen and Laurent Eyer reported that the Hipparcos data shows periodic fluctuations with an amplitude of 0.023 magnitudes, and a period of 7.6805 days.[19] As of 2004 however, it is not confirmed to be variable.[20]