2 Andromedae

2 Andromedae

Template:Location mark Location of 2 Andromedae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	5.09 (5.26 + 7.43)
Characteristics
2 And A
Spectral type	A1V
U−B Template:Engvar	+0.10
B−V Template:Engvar	+0.08
2 And B
Spectral type	F1V/F4V
Variable type	δ Sct?
Astrometry
2 And A
Radial velocity (Rv)	Template:Val km/s
Proper motion (μ)	RA: 56.38 mas/yr Dec.: −4.47 mas/yr
Parallax (π)	7.74±0.51 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	Template:Val
2 And B
Absolute magnitude (MV)	Template:Val
Orbit
Period (P)	Template:Val yr
Semi-major axis (a)	Template:Val″
Eccentricity (e)	Template:Val
Inclination (i)	Template:Val°
Longitude of the node (Ω)	Template:Val°
Periastron epoch (T)	Template:Val
Argument of periastron (ω) (secondary)	Template:Val°
Details
2 And A
Mass	Template:Val Template:Solar mass
Luminosity	130.50 Template:Solar luminosity
Surface gravity (log g)	Template:Val cgs
Temperature	Template:Val K
Rotational velocity (v sin i)	212 km/s
Age	Template:Val Myr
2 And B
Mass	Template:Val Template:Solar mass
Surface gravity (log g)	Template:Val cgs
Temperature	Template:Val K
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBAD	2 And
	2 And A
	2 And B

File:2AndLightCurve.png

A light curve for 2 Andromedae, plotted from TESS data

2 Andromedae, abbreviated 2 And, is a binary star 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. Based upon an annual parallax shift of Template:Val, 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. The pair orbit each other over a period of 74 years with a high eccentricity of 0.8.

The magnitude 5.26 primary, designated component A, is an A-type main-sequence star based on a stellar classification of A1V or A2V, although it may have already left the main sequence. 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. Although 2 Andromedae 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. The star is about 100 million years old and is spinning rapidly with a projected rotational velocity of 212 km/s.

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

External links

• Image 2 Andromedae