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.[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 19m 58.8815s[2] |
| Declination | +47° 14′ 34.576″[2] |
| Apparent magnitude (V) | 10.7 – 11.8 variable [3] |
| Characteristics | |
| Spectral type | C-J5− C25 j3.5[4] |
| Apparent magnitude (B) | 12.84[5] |
| Apparent magnitude (V) | 10.38[5] |
| Apparent magnitude (G) | 9.0005[2] |
| Apparent magnitude (J) | 5.526[6] |
| Apparent magnitude (H) | 4.492[6] |
| Apparent magnitude (K) | 4.018[6] |
| B−V color index | 2.5687[5] |
| Variable type | Lb?[3] |
| Astrometry | |
| Proper motion (μ) | RA: 2.062±0.080 [2] mas/yr Dec.: −3.263±0.072[2] mas/yr |
| Parallax (π) | 0.6515 ± 0.0561 mas[2] |
| Distance | 5,000 ± 400 ly (1,500 ± 100 pc) |
| Details | |
| Radius | 82[2] R☉ |
| Luminosity | 983[2] L☉ |
| Temperature | 3,579[2] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
EU Andromedae was reported to be a carbon star by Oliver J. Lee et al. in 1947, based on objective prism observations undertaken as part of a Dearborn Observatory study of faint red stars.[7][8] Years later, the variability of EU Andromedae was discovered by French amateur astronomer Roger Weber, who examined the star on photographic plates that he and Giuliano Romano had taken from May 1959 through October 1961. Weber announced the discovery in 1962 and noted that it was probably a long period variable, but he could not determine if it was a semi-regular or a Mira variable. It is number 149 in his catalog.[9][10] There is some disagreement in the literature about what class of variable star EU Andromedae belongs to, with some researchers listing it as a slow irregular variable,[3] and others listing it as a semi-regular variable.[11]
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.[8] 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.[12][13]
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.[4]
References
edit- ^ "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 30 October 2024.
- ^ 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.
- ^ a b c d 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.
- ^ 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.
- ^ 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.
- ^ a b c Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (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.
- ^ Lee, Oliver J.; Gore, Greenville D.; Bartlett, Thomas J. (1947). "Carbon Stars in Zones 40[degrees] to 90[degrees]. Dearborn Survey of Faint Red Stars". Annals of the Dearborn Observatory of Northwestern University. 5: 287–292. Bibcode:1947AnDea...5..287L. Retrieved 2 November 2024.
- ^ a b 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.
- ^ Weber, R. (1962). "Onze étoiles variables nouvelles". Journal des Observateurs. 45: 18–30. Bibcode:1962JO.....45...18W. Retrieved 1 November 2024.
- ^ Schweitzer, Emile. "The names and catalogues of variable stars". Observatoire de Strasbourg. Retrieved 1 November 2024.
- ^ Dimitrov, D; Popov, V. (March 2007). "Variable Stars in NSVS Database I. 86 New Variables in Andromeda". Peremennye Zvezdy (Variable Stars). 27 (2). Bibcode:2007PZ.....27....2D. Retrieved 1 November 2024.
- ^ 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.
- ^ 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.