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EU Andromedae

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EU Andromedae
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 23h 19m 58.8815s[1]
Declination +47° 14′ 34.576″[1]
Apparent magnitude (V) 10.7 – 11.8 variable [2]
Characteristics
Spectral type C-J5− C25 j3.5[3]
Apparent magnitude (B) 12.84[4]
Apparent magnitude (V) 10.38[4]
Apparent magnitude (G) 9.0005[1]
Apparent magnitude (J) 5.526[5]
Apparent magnitude (H) 4.492[5]
Apparent magnitude (K) 4.018[5]
B−V color index 2.5687[4]
Variable type Lb?[2]
Astrometry
Proper motion (μ) RA: 2.062±0.080 [1] mas/yr
Dec.: −3.263±0.072[1] mas/yr
Parallax (π)0.6515 ± 0.0561 mas[1]
Distance5,000 ± 400 ly
(1,500 ± 100 pc)
Details
Radius82[1] R☉
Luminosity983[1] L☉
Temperature3,579[1] K
Other designations
2MASS J23195888+4714345, TYC 3640-752-1
Database references
SIMBADdata

EU Andromedae (often abbreviated to EU And) is a carbon star in the constellation Andromeda. Its apparent visual magnitude varies in an irregular manner between 10.7 and 11.8.[2]

Infrared observations of EU Andromedae show the presence of silicate grains, indicating the presence of an oxygen-rich circumstellar shell around the star, a combination known as a silicate star. Subsequently, a water maser was detected around this star (and for the first time around a carbon star), confirming the existence of the shell.[6] The most recent observations suggest that the maser originated in a circumstellar disc, seen nearly edge-on, around an unseen companion with a minimum mass of 0.5 M☉. Carbon dioxide has been detected for the first time in a silicate carbon star around EU Andromedae.[7][8]

EU Andromedae is given as the standard star for the C-J5− spectral class. C-J spectral types are assigned to stars with strong isotopic bands of carbon molecules, defined as the ratio of 12
C
 to 13
C
 being less than four. A more complete spectral type includes the abundance indices C25 j3.5, which indicate the Swan band strength and the isotopic band ratio.[3]

References

  1. ^ a b c d e f g h i 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.
  2. ^ a b c EU And, database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2018-10-17.
  3. ^ a b Barnbaum, Cecilia; Stone, Remington P. S.; Keenan, Philip C. (1996). "A Moderate-Resolution Spectral Atlas of Carbon Stars: R, J, N, CH, and Barium Stars". The Astrophysical Journal Supplement Series. 105: 419. Bibcode:1996ApJS..105..419B. doi:10.1086/192323.
  4. ^ a b c Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy & Astrophysics, 355: L27–L30, Bibcode:2000A&A...355L..27H.
  5. ^ a b c Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; et al. (June 2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues (2246): II/246. Bibcode:2003yCat.2246....0C.
  6. ^ Benson, P. J.; Little-Marenin, I. R. (1987). "A Water Maser Associated with EU Andromedae: A Carbon Star near an Oxygen-rich Circumstellar Shell". Astrophysical Journal Letters. 316: L37. Bibcode:1987ApJ...316L..37B. doi:10.1086/184887.
  7. ^ Ohnaka, K.; Boboltz, D. A. (2008). "Imaging the oxygen-rich disk toward the silicate carbon star EU Andromedae". Astronomy and Astrophysics. 478 (3): 809–814. arXiv:0712.2395. Bibcode:2008A&A...478..809O. doi:10.1051/0004-6361:20079030. S2CID 55988822.
  8. ^ Lloyd Evans, T. (1990). "Carbon stars with silicate dust shells - I. Carbon stars with enhanced 13C (J stars)". Monthly Notices of the Royal Astronomical Society. 243: 336. Bibcode:1990MNRAS.243..336L.
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