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] |
Distance | 1,900 ± 100 ly (600 ± 30 pc) |
Absolute magnitude (MV) | −3.19 [5] |
Details | |
T Vul A | |
Mass | 4.9 [5] M☉ |
Radius | 35.6±4.4 [7] R☉ |
Luminosity | 1,620 [5] L☉ |
Surface gravity (log g) | 1.75 [8] cgs |
Temperature | 6,220 [8] K |
Metallicity [Fe/H] | 0.01 [9] dex |
Age | 120 [9] Myr |
T Vul B | |
Mass | 2.1 [5] M☉ |
Other designations | |
T Vul, AAVSO 2047+27, BD+27° 3890, HD 198726, HIP 102949, HR 7988, SAO 89216 [10] | |
Database references | |
SIMBAD | data |
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]