TT Aquilae
Star in the constellation Aquila / From Wikipedia, the free encyclopedia
TT Aquilae (TT Aql) is a Classical Cepheid (δ Cep) variable star in the constellation Aquila.
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Aquila |
Right ascension | 19h 08m 13.75081s[2] |
Declination | +01° 17′ 55.1600″[2] |
Apparent magnitude (V) | 6.52 - 7.65[3] |
Characteristics | |
Spectral type | G0/2Ib[4] (F6-G5[3]) |
U−B color index | +0.638 - +1.601[5] |
B−V color index | +0.932 - +1.637[5] |
Variable type | δ Cep[3] |
Astrometry | |
Radial velocity (Rv) | 3.00[6] km/s |
Proper motion (μ) | RA: +1.17[2] mas/yr Dec.: −3.33[2] mas/yr |
Parallax (π) | 0.18 ± 1.26 mas[2] |
Absolute magnitude (MV) | −4.26[7] |
Details | |
Mass | 6.2 - 8.6[8] M☉ |
Radius | 83.8 - 100.5[9] R☉ |
Luminosity | 5,284[8] L☉ |
Surface gravity (log g) | 1.10 - 1.70[7] cgs |
Temperature | 5,007 - 5,630[7] (- 6,200[10]) K |
Metallicity | +0.10[7] |
Other designations | |
Database references | |
SIMBAD | data |
Data sources: | |
Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
The visual apparent magnitude of TT Aql ranges from 6.52 to 7.65 over 13.7546 days.[3] The light curve is asymmetric, with the rise from minimum to maximum brightness only taking half the time of the fall from maximum to minimum.[11]
TT Aql is a yellow-white supergiant around five thousand times brighter than the sun. It pulsates and varies in temperature between about 5,000 K and 6,000 K,[10] and the spectral type varies between F6 and G5. The radius is 91.4 R☉ at maximum brightness, varying between 84 R☉ and 100 R☉ as the star pulsates.[9]
Cepheid masses can be estimated using Baade-Wesselink relations and this gives 8.6 M☉. The mass estimated by matching to evolutionary tracks is 7.7 M☉. The mass calculated by modelling the pulsations is 6.2 M☉. The discrepancies between the masses obtained by the different methods occurs for most Cepheid variables.[8]