Astronomy:AA Tauri
 A visual band light curve for AA Tauri, adapted from Bouvier et al. (2013).[1] The main plot shows the long term variation, and the inset plot shows the periodic variation after the dramatic dimming in 2011. | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 34m 55.42019s[2] |
| Declination | +24° 28′ 53.0336″[2] |
| Apparent magnitude (V) | 12.2 to 16.1[3] |
| Characteristics | |
| Spectral type | K7Ve[4] |
| Variable type | T Tauri-type?[4] |
| Astrometry | |
| Radial velocity (Rv) | 16.98±0.04[5] km/s |
| Proper motion (μ) | RA: +5.323[2] mas/yr Dec.: −20.680[2] mas/yr |
| Parallax (π) | 7.4255 ± 0.0868[2] mas |
| Distance | 439 ± 5 ly (135 ± 2 pc) |
| Details | |
| Mass | 0.76[6] M☉ |
| Radius | 1.81[6] R☉ |
| Luminosity | 0.8[6] L☉ |
| Temperature | 4,060[6] K |
| Rotational velocity (v sin i) | 12.8±1.1[5] km/s |
| Age | 2.4[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
AA Tauri is a young variable star in the equatorial constellation of Taurus, located in the Taurus-Auriga star-forming region. It is too faint to view with the naked eye, having an apparent visual magnitude that varies from 12.2 down to 16.1.[3] The star is located approximately 439 light-years (135 parsecs) away from the Sun based on parallax, and is drifting further away with a radial velocity of +17 km/s.[5]
The stellar classification for this object is K7Ve,[4] matching a K-type main-sequence star that displays emission features. It is an eruptive variable of the T Tauri type[3] with an estimated age of 2.4 million years. The object has 76% of the mass of the Sun, 181% of the Sun's radius,[6] and is spinning with a projected rotational velocity of 13 km/s.[5] AA Tauri is radiating 80% of the luminosity of the Sun at an effective temperature of 4,060 K.[6]
Variability
AA Tauri shows brightness variations of one to two magnitudes over an 8.2-day period. The brightness has been described as "roughly constant, interrupted by quasi-cyclic fading episodes".[8] The periodic variations are ascribed to eclipses of the star by a warped dust disk around it.[9]
In 2011, AA Tauri faded by about two magnitudes and has remained at the fainter level since then. The star also became significantly more reddened. The eight-day variations continue, with a maximum brightness now around magnitude 14 and magnitude 16.5 at its faintest. It is theorised that the root cause of this dimness is a warp in the accretion disk, located at a distance of 7.7 AU or more from the centre, that was brought into the line of sight by its elliptical motion around the central star.[1]
Search for planets
In their 2003 paper, Bouvier et al. invoked the possible presence of a substellar object to explain peculiar and periodic eclipses occurring to the young star every 8.3 days, though they considered it unlikely that such a companion could be responsible for said variability.[8] They inferred a mass of 20 times that of Jupiter for the perturbing object and an orbital separation of 0.08 Astronomical Units. Later studies find no evidence for a planet, instead finding multiple rings with accretion streams between them.[9]
References
- ↑ 1.0 1.1 Bouvier, J.; Grankin, K.; Ellerbroek, L. E.; Bouy, H.; Barrado, D. (2013). "AA Tauri's sudden and long-lasting deepening: Enhanced extinction by its circumstellar disk". Astronomy & Astrophysics 557: A77. doi:10.1051/0004-6361/201321389. Bibcode: 2013A&A...557A..77B.
- ↑ 2.0 2.1 2.2 2.3 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.
- ↑ 3.0 3.1 3.2 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ 4.0 4.1 4.2 Herbig, G. H. (1977). "Radial velocities and spectral types of T Tauri stars". Astrophysical Journal 214: 747–758. doi:10.1086/155304. Bibcode: 1977ApJ...214..747H.
- ↑ 5.0 5.1 5.2 5.3 Nguyen, Duy Cuong et al. (February 2012). "Close Companions to Young Stars. I. A Large Spectroscopic Survey in Chamaeleon I and Taurus-Auriga". The Astrophysical Journal 745 (2): 25. doi:10.1088/0004-637X/745/2/119. 119. Bibcode: 2012ApJ...745..119N.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Güdel (2007). "The XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST)". Astronomy and Astrophysics 468 (2): 353–377. doi:10.1051/0004-6361:20065724. Bibcode: 2007A&A...468..353G.
- ↑ "AA Tau". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=AA+Tau.
- ↑ 8.0 8.1 Bouvier (2003). "Eclipses by circumstellar material in the T Tauri star AA Tau. II. Evidence for non-stationary magnetospheric accretion". Astronomy and Astrophysics 409: 169–192. doi:10.1051/0004-6361:20030938. Bibcode: 2003A&A...409..169B.
- ↑ 9.0 9.1 Loomis, Ryan A.; Öberg, Karin I.; Andrews, Sean M.; MacGregor, Meredith A. (2017). "A Multi-ringed, Modestly Inclined Protoplanetary Disk around AA Tau". The Astrophysical Journal 840 (1): 23. doi:10.3847/1538-4357/aa6c63. Bibcode: 2017ApJ...840...23L.
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