EU Andromedae

EU Andromedae

A visual band light curve for EU Andromedae, from AAVSO data[1]
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]
Distance5,000 ± 400 ly
(1,500 ± 100 pc)
Details
Radius82[2] R☉
Luminosity983[2] L☉
Temperature3,579[2] 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.[3]

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.[7] 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.[8][9]

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]

  1. ^ Cite error: The named reference aavso was invoked but never defined (see the help page).
  2. ^ a b c d e f g h i Cite error: The named reference Gaia was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference GCVS was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference barnbaum was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference TYCHO was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference 2MASS Cat was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Benson1987 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Ohnaka2008 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference silicate was invoked but never defined (see the help page).