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2 Andromedae

A light curve for 2 Andromedae, plotted from TESS data
Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda
Right ascension	23 02 36.38176
Declination	+42° 45′ 28.0628″
Apparent magnitude (V)	5.09 (5.26 + 7.43)
Characteristics
2 And A
Spectral type	A1V
U−B color index	+0.10
B−V color index	+0.08
2 And B
Spectral type	F1V/F4V
Variable type	δ Sct?
Astrometry
2 And A
Radial velocity (Rv)	2.1±2.4 km/s
Proper motion (μ)	RA: 56.38 mas/yr Dec.: −4.47 mas/yr
Parallax (π)	7.74 ± 0.51 mas
Distance	420 ± 30 ly (129 ± 9 pc)
Absolute magnitude (MV)	−0.39±0.16
2 And B
Absolute magnitude (MV)	1.88±0.16
Orbit
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
Mass	2.7±0.1 M☉
Luminosity	130.50 L☉
Surface gravity (log g)	3.40±0.12 cgs
Temperature	8,950±250 K
Rotational velocity (v sin i)	212 km/s
Age	100+309 −88 Myr
2 And B
Mass	1.78±0.06 M☉
Surface gravity (log g)	3.90±0.16 cgs
Temperature	7,720±250 K
Other designations
2 And, BD+41° 4665, GJ 886.1, HD 217782, HIP 113788, HR 8766, SAO 52623, PPM 63742, WDS 23026+4245
Database references
SIMBAD	2 And
	2 And A
	2 And B

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 7.7 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 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. 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

1. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
2. ^ van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.Vizier catalog entry
3. ^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
4. ^ Rica Romero, F. M. (2010). "Orbital elements for eight binaries. Study of the nature of wide components. I" (PDF). Revista Mexicana de Astronomía y Astrofísica. 46: 263–277. Bibcode:2010RMxAA..46..263R. Archived from the original (PDF) on 2014-02-25. Retrieved 2014-09-01.
5. ^ Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
6. ^ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
7. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
8. ^ Jerzykiewicz, M.; et al. (2015). "The 2003–2004 multisite photometric campaign for the β Cephei and eclipsing star 16 (EN) Lacertae with an appendix on 2 Andromedae, the variable comparison star". Monthly Notices of the Royal Astronomical Society. 454 (1): 724–740. arXiv:1508.05250. Bibcode:2015MNRAS.454..724J. doi:10.1093/mnras/stv1958. S2CID 119220117.
9. ^ Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.
10. Gullikson, Kevin; et al. (August 2016). "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars". The Astronomical Journal. 152 (2): 13. arXiv:1604.06456. Bibcode:2016AJ....152...40G. doi:10.3847/0004-6256/152/2/40. S2CID 119179065. 40.
11. "2 And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 11, 2018.
12. Burnham, S. W. (1894). "Sixteenth Catalogue of New Double Stars Discovered at the Lick Observatory". Publications of Lick Observatory. 2: 197–205. Bibcode:1894PLicO...2..197B.
13. Paunzen, E.; et al. (June 2003). "A study of lambda Bootis type stars in the wavelength region beyond 7000 Å". Astronomy and Astrophysics. 404 (2): 579–591. arXiv:astro-ph/0303191. Bibcode:2003A&A...404..579P. doi:10.1051/0004-6361:20030284.
14. Roberge, Aki; Weinberger, Alycia J. (March 2008). "Debris Disks around Nearby Stars with Circumstellar Gas". The Astrophysical Journal. 676 (1): 509–517. arXiv:0711.4561. Bibcode:2008ApJ...676..509R. doi:10.1086/527314. S2CID 18407657.

External links

• Image 2 Andromedae

v t e Constellation of Andromeda
Adhil Andromeda in Chinese astronomy List of Andromeda's satellite galaxies List of stars in Andromeda
Stars	Bayer α (Alpheratz) β (Mirach) γ (Almach) δ ε ζ η θ ι κ λ μ ν ξ (Adhil) ο π ρ σ τ υ (Titawin) φ χ ψ ω A b c υ Per (Nembus) Flamsteed 2 3 4 5 6 7 8 9 10 11 12 13 14 (Veritate) 15 18 22 23 26 28 32 36 39 41 44 45 47 55 56 58 59 63 64 65 66 6 Per Variable R T U W Z RT RV RX SU SW TU TW WZ XZ AB AC AD AE AF AR BM BX CC CG CN DS DX EG ET EU FF GO GP GQ GX GR GY HH HN IW KK KX KZ LL LN LP LQ OP OS OU PX PY QR QV QX V385 V428 V439 V455 V529 V807 HR 1 40 56 78 104 122 134 178 275 282 283 289 379 410 483 687 746 748 8884 8925 8950 8962 8973 9011 9074 9075 9105 HD 16175 (Buna) 222155 Other 3XMM J004232.1+411314 ADS 48 HAT-P-6 (Sterrennacht) HAT-P-16 HAT-P-19 HAT-P-28 M31-RV KELT-1 NGC 44 NGC 82 NGC 84 NGC 91 NGC 162 NGC 464 Qatar-3 Qatar-4 Qatar-5 PA-99-N2 WASP-1 WISE 0146+4234 WISE J0005+3737 WISE J004945.61+215120.0
Exoplanets 14 Andromedae b κ Andromedae b υ Andromedae b c d Gliese 15 Ab c HD 13931 b HD 16175 b HAT-P-6b HAT-P-32b WASP-1b WASP-33b Qatar-4b Qatar-5b
Star clusters	NGC 206 272 752 956 7686 Other Mayall II RBC EXT8
Nebulae	NGC 7662
Galaxies	Messier 32 110 NGC 5 11 13 19 20 21 27 39 43 48 49 51 67 68 69 70 71 72 74 76 79 80 81 83 85 86 90 93 94 96 97 108 109 112 140 149 160 169 181 183 184 214 218 226 228 229 233 243 252 258 260 262 280 304 317 389 393 404 425 431 477 512 513 523 528 529 531 536 542 561 605 620 668 679 687 700 703 704 705 708 709 710 712 714 717 721 732 753 759 801 812 834 891 906 910 911 912 913 920 937 980 995 996 999 1000 7640 7836 Numbered I II III IV V VIII IX X XI XVIII XIX XXI Other 3C 66A 3C 66B Andromeda Galaxy Arp 273 Donatiello I UGC 1840
Galaxy clusters Abell 262 NGC 68 group
Astronomical events GRB 101225A SN 1885A (S)
Category

• 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