Theta Apodis
Template:Location mark Location of θ Apodis (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Apus |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 4.65 - 6.20[2] |
| Characteristics | |
| Spectral type | M7 III[3] |
| U−B Template:Engvar | +1.07[4] |
| B−V Template:Engvar | +1.48[4] |
| Variable type | SRb[3] |
| Astrometry | |
| Radial velocity (Rv) | +9.0[5] km/s |
| Proper motion (μ) | RA: −88.586 mas/yr[1] Dec.: −32.655 mas/yr[1] |
| Parallax (π) | 8.3808±0.3574 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | 0.7[3] |
| Details | |
| Mass | Template:Val[6] Template:Solar mass |
| Radius | 208[7] Template:Solar radius |
| Luminosity | Template:Val[6] Template:Solar luminosity |
| Surface gravity (log g) | +0.0[6] cgs |
| Temperature | Template:Val[6] K |
| Metallicity [Fe/H] | −0.20[8] dex |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[9] | |
| Database references | |
| SIMBAD | data |
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Theta Apodis is a variable star in the southern circumpolar constellation of Apus. Its identifier is a Bayer designation that is Latinized from θ Apodis, and abbreviated Tet Aps or θ Aps, respectively. This is a variable star with an apparent visual magnitude range of 4.65 to 6.20,[3] which, according to the Bortle Dark-Sky Scale, means it is a faint star but visible to the naked eye from dark suburban skies. The distance to Theta Apodis is approximately Template:Convert, based upon parallax measurements made from the Gaia telescope.[1] It is unusual in that it is a red star with a high proper motion (greater than 50 milliarcseconds a year).[10]
Benjamin Apthorp Gould announced that Theta Apodis is a variable star, in 1879.[12] It is a semiregular pulsating variable and its brightness changes over a range of 0.56 magnitudes with a period of 119[3] days. A longer period of around 1,000 days has also been detected.[11]
This is an evolved red giant that is currently on the asymptotic giant branch,[13] with a stellar classification of M7 III.[3] It shines with a luminosity approximately 3879 times that of the Sun and has a surface temperature of Template:Val.[7] It is losing mass at the rate of 1.1 × 10−7 times the mass of the Sun per year through its stellar wind. Dusty material ejected from this star is interacting with the surrounding interstellar medium, forming a bow shock as the star moves through the galaxy. The stand-off distance for this front is located at about Template:Convert from Theta Apodis.[13]
Theta Apodis has been identified as an astrometric binary, indicating that it has an orbiting companion that causes gravitational perturbation of the primary star.[14]
References
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