2 Andromedae
{{Short description|Binary star system in the constellation Andromeda}}
{{distinguish|Andromeda II}}
{{Starbox begin}}
{{Starbox image
| image=
{{Location mark
|image=Pegasus constellation map.svg|alt=|float=center|width=280
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=2 And
|x=424|y=22
}}
|caption=Location of 2 Andromedae (circled)
}}
{{Starbox observe
| epoch = J2000
| constell = Andromeda
| dec = {{DEC|+42|45|28.0628}}
| appmag_v = 5.09 (5.26 + 7.43)
}}
{{Starbox character
| component1 = 2 And A
| component2 = 2 And B
| variable2 = δ Sct?
}}
{{Starbox astrometry
| component1 = 2 And A
| parallax = 7.74
| p_error = 0.51
| absmag_v = {{val|−0.39|0.16}}
| component2 = 2 And B
| absmag_v2 = {{val|1.88|0.16}}
}}
{{Starbox orbit
| period = {{val|73.997|0.509}}
| axis = {{Val|0.225|0.011}}
| eccentricity = {{Val|0.800|0.056}}
| inclination = {{Val|21.7|46.0}}
| node = {{Val|159.5|2.0}}
| periastron = {{Val|1870.280|0.595}}
| periarg = {{Val|356.4|3.0}}
}}
{{Starbox detail
| component1 = 2 And A
| radius =
| temperature = {{Val|8950|250|fmt=commas}}
| metal_fe =
| age_myr = {{Val|100|309|88}}
| component2 = 2 And B
| temperature2 = {{Val|7720|250|fmt=commas}}
| gravity2 = {{Val|3.90|0.16}}
}}
{{Starbox catalog
| names = {{odlist | F=2 And | BD=+41°4665 | GJ=886.1 | HD=217782 | HIP=113788 | HR=8766 | SAO=52623 | PPM=63742 | WDS=23026+4245 }}
}}
{{Starbox reference
| Simbad = HD+217782 | sn=2 And
| Simbad2 = 2+And+A | sn2=2 And A
| Simbad3 = 2+And+B | sn3=2 And B
}}
{{Starbox end}}
Image:2AndLightCurve.png 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 {{Val|7.7|ul=mas}}, 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.
References
External links
- [http://aladin.u-strasbg.fr/AladinPreview?-c=*+++2+And&ident=*+++2+And&submit=Aladin+previewer Image 2 Andromedae]
{{Stars of Andromeda}}
{{DEFAULTSORT:2 Andromedae}}
Category:A-type main-sequence stars
Category:F-type main-sequence stars
Category:Delta Scuti variables