T Vulpeculae

T Vulpeculae

A visual band light curve for T Vulpeculae, adapted from Kiss (1998)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Vulpecula
Right ascension 20h 51m 28.23825s[2]
Declination +28° 15′ 01.8166″[2]
Apparent magnitude (V) 5.754[3] (5.41 – 6.09)[4]
Characteristics
Spectral type F5 Ib + A0.8 V[5]
B−V color index +0.616±0.049[6]
Variable type δ Cep[4]
Astrometry
Radial velocity (Rv)−2.6±0.6[6] km/s
Proper motion (μ) RA: +3.496[2] mas/yr
Dec.: −15.087[2] mas/yr
Parallax (π)1.6738 ± 0.0891 mas[2]
Distance1,900 ± 100 ly
(600 ± 30 pc)
Absolute magnitude (MV)−3.19[5]
Details
T Vul A
Mass4.9[5] M☉
Radius35.6±4.4[7] R☉
Luminosity1,620[5] L☉
Surface gravity (log g)1.75[8] cgs
Temperature6,220[8] K
Metallicity [Fe/H]0.01[9] dex
Age120[9] Myr
T Vul B
Mass2.1[5] M☉
Other designations
T Vul, BD+27° 3890, HD 198726, HIP 102949, HR 7988, SAO 89216[10]
Database references
SIMBADdata

T Vulpeculae is a possible binary star system in the northern constellation of Vulpecula, near the star Zeta Cygni, close to the pair 31 Vulpeculae and 32 Vulpeculae.[11] It is visible to the naked eye with an apparent visual magnitude that ranges around 5.75.[3] The distance to this system is around 1,900 light years, as determined from its annual parallax shift of 1.67 mas.[2]

A well-studied Classical Cepheid variable and one of the brightest known,[12] the apparent magnitude of T Vulpeculae ranges from 5.41 to 6.09[4] over a period of 4.435 days.[3] It is a yellow-white hued supergiant of spectral type F5 Ib.[5] The variability of T Vul was discovered in 1885 by Edwin Sawyer.[13] Observations between 1885 and 2003 shows a small but continuous decrease in the period of variability amounting to 0.25 seconds per year.[14]

The companion star was detected in 1992;[12] it is an A-type main-sequence star with a class of A0.8 V and 2.1 times the Sun's mass.[5] Orbital periods of 738 and 1,745 days have been proposed for the pair, although, as of 2015, there remains doubt as to whether this is an actual binary system.[15]

  1. ^ Cite error: The named reference Kiss was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Evans2015b was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference AAVSOT was invoked but never defined (see the help page).
  5. ^ a b c d e f g Cite error: The named reference evans13 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Gallenne2012 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference gray2001 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference marsakov2013 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Moore2000 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference Evans1992 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Sawyer1886 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Meyer was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Gallenne2015 was invoked but never defined (see the help page).