Astronomy:Theta Apodis
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Apus |
| Right ascension | 14h 05m 19.881s[1] |
| Declination | −76° 47′ 48.34″[1] |
| Apparent magnitude (V) | 4.65 - 6.20[2] |
| Characteristics | |
| Spectral type | M7 III[3] |
| U−B color index | +1.07[4] |
| B−V color index | +1.48[4] |
| Variable type | SRb[3] |
| Astrometry | |
| Radial velocity (Rv) | +9.0[5] km/s |
| Proper motion (μ) | RA: −88.586[1] mas/yr Dec.: −32.655[1] mas/yr |
| Parallax (π) | 8.3808 ± 0.3574[1] mas |
| Distance | 390 ± 20 ly (119 ± 5 pc) |
| Absolute magnitude (MV) | 0.7[3] |
| Details | |
| Mass | 1.0±0.3[6] M☉ |
| Radius | 208[7] R☉ |
| Luminosity | 3,050±460[6] L☉ |
| Surface gravity (log g) | +0.0[6] cgs |
| Temperature | 2,850±160[6] K |
| Metallicity [Fe/H] | −0.20[8] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
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 390 light-years (120 parsecs), 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 3,131 K.[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 0.134 ly (0.041 pc) 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
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ VSX, https://www.aavso.org/vsx/index.php?view=detail.top&oid=844, retrieved 2018-10-29.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Yeşilyaprak, C. et al. (December 2004), "Period-luminosity relation for M-type semiregular variables from Hipparcos parallaxes", Monthly Notices of the Royal Astronomical Society 355 (2): 601–607, doi:10.1111/j.1365-2966.2004.08344.x, Bibcode: 2004MNRAS.355..601Y.
- ↑ 4.0 4.1 Wisse, P. N. J. (May 1981), "Three colour observations of southern red variable giant stars", Astronomy and Astrophysics Supplement Series 44: 273–303, Bibcode: 1981A&AS...44..273W.
- ↑ Feast, M. W. et al. (1972), "The kinematics of semi-regular red variables in the solar neighbourhood", Monthly Notices of the Royal Astronomical Society 158: 23–46, doi:10.1093/mnras/158.1.23, Bibcode: 1972MNRAS.158...23F.
- ↑ 6.0 6.1 6.2 6.3 Ohnaka, K. (January 2014), "High spectral resolution spectroscopy of the SiO fundamental lines in red giants and red supergiants with VLT/VISIR", Astronomy and Astrophysics 561, doi:10.1051/0004-6361/201321581, Bibcode: 2014A&A...561A..47O, https://www.aanda.org/articles/aa/pdf/2014/01/aa21581-13.pdf
- ↑ 7.0 7.1 McDonald, I. et al. (2017), "Fundamental parameters and infrared excesses of Tycho-Gaia stars", Monthly Notices of the Royal Astronomical Society 471 (1): 770, doi:10.1093/mnras/stx1433, Bibcode: 2017MNRAS.471..770M.
- ↑ Anders, F. et al. (2019), "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18", Astronomy and Astrophysics 628: A94, doi:10.1051/0004-6361/201935765, Bibcode: 2019A&A...628A..94A
- ↑ "tet Aps -- Semi-regular pulsating Star", SIMBAD (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+122250, retrieved 2012-07-08.
- ↑ Jiménez-Esteban, F. M. et al. (2012), "Identification of red high proper-motion objects in Tycho-2 and 2MASS catalogues using Virtual Observatory tools", Astronomy & Astrophysics 539: 12, doi:10.1051/0004-6361/201118375, Bibcode: 2012A&A...539A..86J
- ↑ 11.0 11.1 Moon, T. T. (2008), "Combining Visual and Photoelectric Observations of Semiregular Red Variables", Journal of the American Association of Variable Star Observers 36 (1): 77, Bibcode: 2008JAVSO..36...77M
- ↑ Gould, Benjamin Apthorp (1879), "Uranometria Argentina: Brightness and position of every fixed star, down to the seventh magnitude, within one hundred degrees of the South Pole; with atlas", Resultados del Observatorio Nacional Argentino 1: I-387, Bibcode: 1879RNAO....1....1G, https://articles.adsabs.harvard.edu/pdf/1879RNAO....1D...1G, retrieved 19 December 2024
- ↑ 13.0 13.1 Cox, N. L. J. et al. (January 2012), "A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants", Astronomy & Astrophysics 537: A35, doi:10.1051/0004-6361/201117910, Bibcode: 2012A&A...537A..35C. See table 1, IRAS 14003-7633.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E
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