2 Andromedae

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title: "2 Andromedae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["a-type-main-sequence-stars", "f-type-main-sequence-stars", "delta-scuti-variables", "shell-stars", "binary-stars", "circumstellar-disks", "andromeda-(constellation)", "durchmusterung-objects", "flamsteed-objects", "gliese-and-gj-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects"] description: "Binary star system in the constellation Andromeda" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/2_Andromedae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Binary star system in the constellation Andromeda ::

| image= |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) | epoch = J2000 | constell = Andromeda | ra = | dec = | appmag_v = 5.09 (5.26 + 7.43) | component1 = 2 And A | class = A1V | b-v = +0.08 | u-b = +0.10 | component2 = 2 And B | class2 = F1V/F4V | variable2 = δ Sct? | component1 = 2 And A | radial_v = | prop_mo_ra = 56.38 | prop_mo_dec = −4.47 | parallax = 7.74 | p_error = 0.51 | parallax_footnote = | absmag_v = | component2 = 2 And B | absmag_v2 = | reference = | period = | axis = | eccentricity = | inclination = | node = | periastron = | periarg = | component1 = 2 And A | mass = | radius = | luminosity = 130.50 | temperature = | metal_fe = | gravity = | rotational_velocity = 212 | age_myr = | component2 = 2 And B | mass2 = | temperature2 = | gravity2 = | names = | Simbad = HD+217782 | sn=2 And | Simbad2 = 2+And+A | sn2=2 And A | Simbad3 = 2+And+B | sn3=2 And B

::figure[src="https://upload.wikimedia.org/wikipedia/commons/7/7e/2AndLightCurve.png" caption="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 , 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

References

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