2 Andromedae

Not to be confused with Andromeda II.
2 Andromedae

A light curve for 2 Andromedae, plotted from TESS data[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 23h 02m 36.38176s[2]
Declination +42° 45′ 28.0628″[2]
Apparent magnitude (V) 5.09[3] (5.26 + 7.43)[4]
Characteristics
2 And A
Spectral type A1V[5]
U−B color index +0.10[6]
B−V color index +0.08[6]
2 And B
Spectral type F1V/F4V[4]
Variable type δ Sct?[4]
Astrometry
2 And A
Radial velocity (Rv)2.1±2.4[7] km/s
Proper motion (μ) RA: 56.38[2] mas/yr
Dec.: −4.47[2] mas/yr
Parallax (π)7.74 ± 0.51 mas[2]
Distance420 ± 30 ly
(129 ± 9 pc)
Absolute magnitude (MV)−0.39±0.16[8]
2 And B
Absolute magnitude (MV)1.88±0.16[8]
Orbit[4]
Period (P)73.997±0.509 yr
Semi-major axis (a)0.225±0.011″
Eccentricity (e)0.800±0.056
Inclination (i)21.7±46.0°
Longitude of the node (Ω)159.5±2.0°
Periastron epoch (T)1870.280±0.595
Argument of periastron (ω)
(secondary)		356.4±3.0°
Details
2 And A
Mass2.7±0.1[8] M☉
Luminosity130.50[3] L☉
Surface gravity (log g)3.40±0.12[8] cgs
Temperature8,950±250[8] K
Rotational velocity (v sin i)212[9] km/s
Age100+309
−88[10] Myr
2 And B
Mass1.78±0.06[8] M☉
Surface gravity (log g)3.90±0.16[8] cgs
Temperature7,720±250[8] K
Other designations
2 And, BD+41° 4665, GJ 886.1, HD 217782, HIP 113788, HR 8766, SAO 52623, PPM 63742, WDS 23026+4245[11]
Database references
SIMBAD2 And
2 And A
2 And B

2 Andromedae, abbreviated 2 And, is a binary star[4] system in the northern constellation of Andromeda. 2 Andromedae is the Flamsteed designation. It is a faint star system but visible to the naked eye with a combined apparent visual magnitude of 5.09.[3] Based upon an annual parallax shift of 7.7 mas,[2] it is located 420 light years away. The binary nature of the star was discovered by American astronomer Sherburne Wesley Burnham at Lick Observatory in 1889.[12] The pair orbit each other over a period of 74 years with a high eccentricity of 0.8.[4]

The magnitude 5.26[4] primary, designated component A, is an A-type main-sequence star based on a stellar classification of A1V[5] or A2V,[4] although it may have already left the main sequence.[8] It was identified as a candidate Lambda Boötis star, but this was ruled out by Paunzen et al. (2003) as it doesn't match the typical characteristics of these objects.[13] Although 2 And does not display a significant infrared excess, it is a shell star that displays varying absorption features due to circumstellar dust grains. This may indicate it has an orbiting debris disk containing gas that is being viewed edge-on.[14] The star is about 100 million years old and is spinning rapidly with a projected rotational velocity of 212 km/s.[9]

The magnitude 7.43[4] secondary companion, component B, is a suspected variable star and may be a Delta Scuti variable.[4] Alternatively, it may be an ellipsoidal variable with a brown dwarf companion.[8] It is an F-type main-sequence star with a class of F1V/F4.[4]

  1. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference van Leeuwen2007 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i j k Cite error: The named reference Rica Romero2010 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Abt1995 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference EgUBV was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Gontcharov was invoked but never defined (see the help page).
  8. ^ a b c d e f g h i j Cite error: The named reference Jerzykiewicz2015 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference zorec2012 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Gullikson2016 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Burnham1894 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Paunzen2003 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Roberge2008 was invoked but never defined (see the help page).