HD 192685
B-type star in the constellation Vulpecula
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HD 192685, also known as QR Vulpeculae or HR 7739, is a binary star[3] about 1,000 ly away in the Vulpecula constellation. It is visible to the naked eye.
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vulpecula |
| Right ascension | 20h 15m 15.89542s[1] |
| Declination | +25° 35′ 31.0549″[1] |
| Apparent magnitude (V) | 4.60 - 4.80[2] |
| Characteristics | |
| Spectral type | B3Ve + A7V[3] |
| U−B color index | −0.73[4] |
| Variable type | γ Cas[2] |
| Astrometry | |
| Radial velocity (Rv) | −7.00[5] km/s |
| Proper motion (μ) | RA: +6.93[1] mas/yr Dec.: −3.89[1] mas/yr |
| Parallax (π) | 3.29±0.51 mas[1] |
| Distance | approx. 1,000 ly (approx. 300 pc) |
| Absolute magnitude (MV) | −2.56[6] |
| Details | |
| A | |
| Mass | 4.7[3] M☉ |
| Luminosity | 3331[6] L☉ |
| Surface gravity (log g) | 3.49[7] cgs |
| Temperature | 18,700[8] K |
| Metallicity [Fe/H] | −0.10[7] dex |
| Rotational velocity (v sin i) | 160[9] km/s |
| Age | 100[3] Myr |
| B | |
| Mass | 1.8[3] M☉ |
| Age | 100[3] Myr |
| Other designations | |
| QR Vul, BD+25°4165, CCDM J20153+2536AB, GC 28140, HIP 99824, HR 7739, HD 192685, SAO 88410, WDS J20153+2536AB | |
| Database references | |
| SIMBAD | data |
Description
In 1982 Krešimir Pavlovski and Hrvoje Božić announced their discovery that HD 192685 is a variable star.[12] It was given its variable star designation, QR Vulpeculae, in 1985.[13] HD 192685 varies slightly in brightness and is classified as a γ Cassiopeiae variable.[2]
The stellar components have a projected separation of 70 astronomical units and have an estimated orbital period of 217 years. Component A is a Be star with a spectral type of B3Ve, having a mass 4.7 times that of the Sun, while component B has a class of A3V and is 1.8 times as massive as the Sun.[3]
In July 1982, HD 192685 was observed to have its Hα spectral line, previously a broad absorption line,[10] in emission with a central absorption core, and it was classified as a Be star.[14] In late 1982 the emission increased in strength and the star brightened rapidly and briefly by over 0.1 magnitudes.[10]
HD 192685 has excess infrared emissions (12-100 μm) which are interpreted to be free-free radiation in the gas surrounding the star.[15]