Alpha Telescopii
 Location of α Telescopii (circled) |
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| Constellation | Telescopium |
| Right ascension | 18h 26m 58.41604s[1] |
| Declination | –45° 58′ 06.4498″[1] |
| Apparent magnitude (V) | 3.51[2] |
| Characteristics | |
| Spectral type | B3 IV[3] |
| U−B color index | –0.64[2] |
| B−V color index | –0.17[2] |
| Variable type | SPB[4] |
| Astrometry | |
| Radial velocity (Rv) | –0.2[5] km/s |
| Proper motion (μ) | RA: –16.95[1] mas/yr Dec.: –53.09[1] mas/yr |
| Parallax (π) | 11.74 ± 0.17[1] mas |
| Distance | 278 ± 4 ly (85 ± 1 pc) |
| Details | |
| Mass | 5.2 ± 0.4[4] M☉ |
| Radius | 3.3 ± 0.5[4] R☉ |
| Surface gravity (log g) | 4.12 ± 0.20[4] |
| Luminosity | 794[4] L☉ |
| Temperature | 16,700 ± 800[4] K |
| Rotational velocity (v sin i) | 14 ± 8[4] km/s |
| Other designations | |
Alpha Telescopii (α Tel, α Telescopii) is the brightest star in the constellation Telescopium, with an apparent visual magnitude of 3.5.[2] Ptolemy included it in constellation Corona Australis, but it was moved to Telescopium when that constellation was created by Nicolas Louis de Lacaille in the 18th century.[7] Parallax measurements put it at a distance of 278 light-years (85 parsecs) from Earth.
This star is much larger than the Sun, with about five times the mass and three times the radius.[4] The spectrum of the star matches a stellar classification of B3 IV,[3] where the luminosity class of 'IV' indicates this is a subgiant star that has nearly exhausted the supply of hydrogen at its core and is evolving away from the main sequence. Alpha Telescopii is a bright star that is radiating nearly 800 times the Sun's luminosity. This energy is being emitted from the star's outer envelope at an effective temperature of around 16,700 K,[4] giving it the characteristic blue-white hue of a B-type star.[8]
This is a type of variable star known as a slowly pulsating B star. It has a longitudinal magnetic field with a mean strength of –233 ± 43 G.[4] A projected stellar rotation velocity of about 14 km s–1 is considered low for a star of this type,[4] which may indicate it is being viewed from nearly pole-on.[9]
[edit] References
- ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, Bibcode 2007A&A...474..653V, doi:10.1051/0004-6361:20078357
- ^ a b c d Johnson, H. L. et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory 4 (99). Bibcode 1966CoLPL...4...99J.
- ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode 1975mcts.book.....H
- ^ a b c d e f g h i j k Hubrig, S. et al. (April 2009), "New magnetic field measurements of β Cephei stars and slowly pulsating B stars", Astronomische Nachrichten 330 (4): 317, Bibcode 2009AN....330..317H, doi:10.1002/asna.200811187
- ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode 1967IAUS...30...57E
- ^ "alf Tel -- Star", SIMBAD (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alpha+Telescopii, retrieved 2012-01-15
- ^ Ridpath, Ian, "Corona Austalis, the Southern Crown", Ian Ridpath's Star Tales, http://www.ianridpath.com/startales/coronaaustralis.htm, retrieved 2012-01-15
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16
- ^ Kaler, James B., "ALPHA TEL (Alpha Telescopii)", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/alphatel.html, retrieved 2012-01-15
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