27 Hydrae

27 Hydrae
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 09h 20m 29.01857s[1]
Declination −09° 33′ 20.5054″[1]
Apparent magnitude (V) 4.818[2] (4.91 + 7.03 + 10.99)[3]
Characteristics
Spectral type K0III[4] + F4V + K2V[5]
Astrometry
Radial velocity (Rv)+25.60±0.13[6] km/s
Proper motion (μ) RA: −12.48[1] mas/yr
Dec.: −27.37[1] mas/yr
Parallax (π)14.66 ± 0.31 mas[1]
Distance222 ± 5 ly
(68 ± 1 pc)
Details
A
Mass2.17[2] M☉
Radius11[6] R☉
Luminosity57.5[2] L☉
Surface gravity (log g)2.9[6] cgs
Temperature4,965±26[2] K
Metallicity [Fe/H]−0.07[6] dex
Rotational velocity (v sin i)3.3[6] km/s
Age1.91[2] Gyr
B
Radius1.82[7] R☉
Luminosity5.885[7] L☉
Temperature6,664[7] K
C
Radius0.72[8] R☉
Luminosity0.227[8] L☉
Temperature4,685[8] K
Other designations
CCDM J09204-0934, WDS J09204-0934[9]
A: 27 Hya, BD−08°2643, HD 80586, HIP 45811, HR 3709, SAO 136768
B: BD−09°2801, HD 80550, HIP 45802, SAO 136767
C: TYC 5463-1518-1
Database references
SIMBADdata
B
C

27 Hydrae is a triple star system[5] system in the equatorial constellation of Hydra,[9] located 222 light years away from the Sun.[1] It is visible to the naked eye as a faint, orange-hued star with a combined apparent visual magnitude of 4.82.[2] The system is moving further from the Earth with a heliocentric radial velocity of +25.6 km/s.[6]

The magnitude 4.91[5] primary, component A, is an aging giant star with a stellar classification of K0 III.[4] It is a red clump giant,[10] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is 1.9[2] billion years old with 2.17[2] times the mass of the Sun. It has swelled to 11[6] times the Sun's radius and is radiating 57.5[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,965 K.[2] The star is suspected to host a low-mass companion.[11]

The stellar companions to this star, designated components B and C, lie at an angular separation of 229.10″ from the primary, and form a binary pair with a separation of 9.20″ as of 2015.[3] The brighter member of the pair, component B, is a seventh magnitude F-type main-sequence star with a class of F4 V, while its companion is an eleventh magnitude K-type main-sequence star with a class of K2 V.[5]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f g h i j Cite error: The named reference Luck2015 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Houk1999 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  6. ^ a b c d e f g Cite error: The named reference Massarotti2008 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference dr2b was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference dr2c was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Alves2000 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Toyota2009 was invoked but never defined (see the help page).