Theta Andromedae

Theta Andromedae
Location of θ Andromedae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 00h 17m 05.50236s[1]
Declination +38° 40′ 53.8886″[1]
Apparent magnitude (V) 4.61[2]
Characteristics
Evolutionary stage main sequence[3]
Spectral type A2 V[4]
U−B color index +0.05[2]
B−V color index +0.06[2]
Variable type Constant[5]
Astrometry
Radial velocity (Rv)0.9[6] km/s
Proper motion (μ) RA: −57.551(307)[1] mas/yr
Dec.: −14.795(155)[1] mas/yr
Parallax (π)18.8747 ± 0.4251 mas[1]
Distance173 ± 4 ly
(53 ± 1 pc)
Absolute magnitude (MV)−0.25[7]
Orbit[8]
Period (P)1033+91
−77 days
Semi-major axis (a)25+32
−13 mas
Eccentricity (e)0.95+0.04
−0.40
Inclination (i)69+8
−22°
Longitude of the node (Ω)263+50
−156°
Periastron epoch (T)238+343
−143
Argument of periastron (ω)
(secondary)		89+175
−29°
Details
A
Mass2.83±0.08[3] M☉
Luminosity113[7] L☉
Surface gravity (log g)3.95[9] cgs
Temperature8,960[9] K
Metallicity [Fe/H]+0.14[9] dex
Rotational velocity (v sin i)102[3] km/s
Other designations
θ And, 24 Andromedae, BD+37°34, HD 1280, HIP 1366, HR 63, SAO 53777, PPM 65154[10]
Database references
SIMBADdata

Theta Andromedae is a binary star[11] system in the northern constellation of Andromeda. Theta Andromedae, Latinized from θ Andromedae, is its Bayer designation. It is located at a distance of approximately 173 light-years (53 parsecs) from the Sun,[1] and has an apparent visual magnitude of 4.6.[2] On the Bortle Dark-Sky Scale, this makes it visible to the naked eye from outside urban regions. Based on its motion through space, this system appears to be a member of the Sirius supercluster.[12]

The brighter component is a white hued A-type main-sequence star with a stellar classification of A2 V.[4] It is one of the least photometrically variable stars known.[5] The star shows a high rate of rotation with a projected rotational velocity of 102 km/s.[3] It has an estimated 2.8[3] times the mass of the Sun and is radiating 113[7] times the Sun's luminosity from its photosphere at an effective temperature of 8,960 K.[9] The relatively high chemical abundances of iron and heavier elements suggests it may be a fast rotating Am star.[5]

A stellar companion was detected in 1986 and reported in 1989.[13] This fainter companion is separated from Theta Andromedae by 0.06 arcseconds.[11] The secondary appears to be a massive, possibly A-type, star orbiting at a distance of around one astronomical unit with a period of 2.83 years and a large orbital eccentricity (ovalness) of 0.95.[8]

  1. ^ a b c d e f Cite error: The named reference Gaia EDR3 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference clpl4_99 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Zorec_Royer_2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference aj74_375 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Koçer_et_al_2003 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference rgcrv was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference apjss166_1_341 was invoked but never defined (see the help page).
  9. ^ a b c d Cite error: The named reference aaa294_2_536 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Palous_Hauck_1986 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference McAlister_et_al_1989 was invoked but never defined (see the help page).