TT Aquilae

TT Aquilae

A visual band light curve for TT Aquilae, adapted from Kiss (1998)[1]
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
Mass6.2 - 8.6[8] M☉
Radius83.8 - 100.5[9] R☉
Luminosity5,284[8] L☉
Surface gravity (log g)1.10 - 1.70[7] cgs
Temperature5,007 - 5,630[7] (- 6,200[10]) K
Metallicity+0.10[7]
Other designations
TT Aql, HD 178359, HIP 93390, BD+01°3899, SAO 124305
Database references
SIMBADdata
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

TT Aquilae (TT Aql) is a Classical Cepheid (δ Cep) variable star in the constellation Aquila.

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]

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