28 Andromedae

28 Andromedae (abbreviated 28 And) is a Delta Scuti variable star in the constellation Andromeda. 28 Andromedae is the Flamsteed designation. It also bears the variable star name GN Andromedae. Its apparent magnitude is 5.214, varying by less than 0.1 magnitudes.

28 Andromedae
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension  00h 30m 07.36s[1]
Declination +29° 45′ 05.6″[1]
Apparent magnitude (V) 5.214[2]
Characteristics
Spectral type A7 III[3]
U−B color index +0.08[4]
B−V color index +0.26[4]
Variable type δ Sct[5]
Astrometry
Radial velocity (Rv)−10.3 ± 0.6[6] km/s
Proper motion (μ) RA: 44.983±0.344[7] mas/yr
Dec.: 55.668±0.176[7] mas/yr
Parallax (π)16.3540 ± 0.1743[7] mas
Distance199 ± 2 ly
(61.1 ± 0.7 pc)
Absolute magnitude (MV)1.29[8]
Details
Mass1.77[9] M☉
Radius3.19[7] R☉
Luminosity25.007[7] L☉
Surface gravity (log g)3.95±0.06[10] cgs
Temperature7,335±69[10] K
Metallicity [Fe/H]−0.09±0.05[10] dex
Rotational velocity (v sin i)21±2[11] km/s
Age1.159[9] Gyr
Other designations
BD+28°75, HD 2628, HIP 2355, HR 114, SAO 74041
Database references
SIMBADdata

Description

28 Andromedae is an A-type giant star,[3] meaning it is colored bluish-white. Parallax estimates made by the Hipparcos spacecraft put the star at a distance of about 199 light years (61 parsecs).[1] It is moving towards the solar system at a velocity of 10.30 km/s.[6]

Multiplicity of the system

Two stars near 28 Andromedae share a common proper motion with the primary star, which is then a candidate triple system. The orbital parameters are currently unknown. The second and third component have masses of 0.71 M☉ and 0.14 M☉ respectively.[12]

Variability cycle

28 Andromedae A is a Delta Scuti variable, so it displays small luminosity variations at timescales less than a day due to star pulsation. There is evidence for two periodic cycles of 5,014 and 5,900 seconds, respectively. The amplitude variations, though, are not constant in time, and the pulsation modes are not radial.[13]

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References
  1. 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.Vizier catalog entry
  2. Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  3. Cowley, A.; Fraquelli, D. (1974). "MK Spectral Types for Some Bright F Stars". Publications of the Astronomical Society of the Pacific. 86 (509): 70. Bibcode:1974PASP...86...70C. doi:10.1086/129562.
  4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  5. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  6. 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.
  7. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  8. Huang, W.; et al. (2012). "A catalogue of Paschen-line profiles in standard stars". Astronomy & Astrophysics. 547: A62. arXiv:1210.7893. Bibcode:2012A&A...547A..62H. doi:10.1051/0004-6361/201219804.
  9. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.
  10. Prugniel, Ph. (1986). "The atmospheric parameters and spectral interpolator for the MILES stars". Astronomy & Astrophysics. 531: A165. arXiv:1104.4952. Bibcode:2011A&A...531A.165P. doi:10.1051/0004-6361/201116769.
  11. Royer, F.; Grenier, S.; Baylac, M. -O.; Gómez, A. E.; Zorec, J. (2002). "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i". Astronomy and Astrophysics. 393: 897–911. arXiv:astro-ph/0205255. Bibcode:2002A&A...393..897R. doi:10.1051/0004-6361:20020943.
  12. De Rosa, R. J.; Patience, J.; Wilson, P. A.; Schneider, A.; Wiktorowicz, S. J.; Vigan, A.; Marois, C.; Song, I.; Macintosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Thomas, S.; Lai, O. (2014). "The VAST Survey - III. The multiplicity of A-type stars within 75 pc". Monthly Notices of the Royal Astronomical Society. 437 (2): 1216–1240. Bibcode:2014MNRAS.437.1216D. doi:10.1093/mnras/stt1932.
  13. Rodriguez, E.; Rolland, A.; Lopez-Gonzalez, M. J.; Costa, V. (1998). "Extreme amplitude variations in 28 And". Astronomy and Astrophysics. 338: 905–908. Bibcode:1998A&A...338..905R.
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