T Vulpeculae information

T Vulpeculae
	; A visual band light curve for T Vulpeculae, adapted from Kiss (1998)
Observation data; Epoch J2000 Equinox J2000
Constellation	Vulpecula
Right ascension	20h 51m 28.23825s
Declination	+28° 15′ 01.8166″
Apparent magnitude (V)	5.754 (5.41 – 6.09)
Characteristics
Spectral type	F5 Ib + A0.8 V
B−V color index	+0.616±0.049
Variable type	δ Cep
Astrometry
Radial velocity (Rv)	−2.6±0.6 km/s
Proper motion (μ)	RA: +3.496 mas/yr ; Dec.: −15.087 mas/yr
Parallax (π)	1.6738 ± 0.0891 mas
Distance	1,900 ± 100 ly ; (600 ± 30 pc)
Absolute magnitude (MV)	−3.19
Details
T Vul A
Mass	4.9 M☉
Radius	35.6±4.4 R☉
Luminosity	1,620 L☉
Surface gravity (log g)	1.75 cgs
Temperature	6,220 K
Metallicity [Fe/H]	0.01 dex
Age	120 Myr
T Vul B
Mass	2.1 M☉
Other designations
	T Vul, BD+27° 3890, HD 198726, HIP 102949, HR 7988, SAO 89216
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]

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[Anderson2012-6] Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).

[Gallenne2012-7] Cite error: The named reference Gallenne2012 was invoked but never defined (see the help page).

[gray2001-8] Cite error: The named reference gray2001 was invoked but never defined (see the help page).

[marsakov2013-9] Cite error: The named reference marsakov2013 was invoked but never defined (see the help page).

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[Evans1992-12] Cite error: The named reference Evans1992 was invoked but never defined (see the help page).

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[Gallenne2015-15] Cite error: The named reference Gallenne2015 was invoked but never defined (see the help page).

Observation data Epoch J2000 Equinox J2000
A visual band light curve for T Vulpeculae, adapted from Kiss (1998)^[1]
Constellation	Vulpecula
Right ascension	20^h 51^m 28.23825^s^[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 (R_v)	−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 (M_V)	−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, BD+27° 3890, HD 198726, HIP 102949, HR 7988, SAO 89216^[10]
Database references
SIMBAD	data

T Vulpeculae information

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QQ Vulpeculae

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ER Vulpeculae

PU Vulpeculae

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