Alpha Pictoris
 The red dot shows the location of Alpha Pictoris. |
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| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Pictor |
| Right ascension | 06h 48m 11.4523s[1] |
| Declination | −61° 56′ 29.010″[1] |
| Apparent magnitude (V) | 3.30 |
| Characteristics | |
| Spectral type | A7IV[2] |
| U−B color index | +0.13[3] |
| B−V color index | +0.21[3] |
| Astrometry | |
| Radial velocity (Rv) | +20.6[4] km/s |
| Proper motion (μ) | RA: -68.39[1] mas/yr Dec.: 242.03[1] mas/yr |
| Parallax (π) | 32.96 ± 2.14[1] mas |
| Distance | 99 ± 6 ly (30 ± 2 pc) |
| Absolute magnitude (MV) | 0.86[5] |
| Details | |
| Mass | 2.04[5] M☉ |
| Radius | 1.6[6] R☉ |
| Luminosity | 13[7] L☉ |
| Surface gravity (log g) | 3.48[8] |
| Temperature | 7,530[8] K |
| Rotational velocity (v sin i) | 206[9] km/s |
| Age | 0.66[10][11] Gyr |
| Other designations | |
Alpha Pictoris (α Pic, α Pictoris) is the brightest star in the constellation Pictor with an apparent magnitude of 3.30. It is located about 99 light years from the Sun.[1] This is a relatively young Lambda Boötis star[13] at 660 million years of age,[10][11] and is rotating rapidly with a projected stellar rotation rate of 206 km/s or greater.[9]
Spectroscopy shows narrow, time-varying absorption features being caused by circumstellar gas moving toward the star. This is not the result of interstellar matter, but instead may be a shell of gas along the orbital plane. Alpha Pictoris is categorized as a rapidly rotating shell star that may have recently ejected mass from the outer atmosphere.[2][8]
Data from the Hipparcos mission indicate this may be an unresolved binary with a companion orbiting at a semimajor axis of 1 AU, or the same distance that the Earth orbits the Sun.[13] Alpha Pictoris is an X-ray source, which is unusual for an A-type star since stellar models don't predict them to have magnetic dynamos. This emission may instead be originating from the companion.[8][14]
The space velocity components of this star are U = -22, V = -20 and W = -9 km/s.[15]
Alpha Pictoris has the distinction of being the south pole star of Mercury.[citation needed]
[edit] References
- ^ a b c d e f Perryman, M. A. C. et al (1997). "The Hipparcos Catalogue". Astronomy & Astrophysics 323: L49–L52. Bibcode 1997A&A...323L..49P.
- ^ a b Roberge, Aki; Weinberger, Alycia J. (March 2008). "Debris Disks around Nearby Stars with Circumstellar Gas". The Astrophysical Journal 676 (1): 509–517. Bibcode 2008ApJ...676..509R. doi:10.1086/527314. http://iopscience.iop.org/0004-637X/676/1/509/fulltext.
- ^ a b Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar & Planetary Laboratory 4: 99–110. Bibcode 1966CoLPL...4...99J.
- ^ Wilson, R. E. (1953). General Catalogue of Stellar Radial. Washington D.C.: Carnegie Institude Publication 601. Bibcode 1953GCRV..C......0W.
- ^ a b Pizzolato, N.; Maggio, A.; Sciortino, S. (September 2000), "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases", Astronomy and Astrophysics 361: 614–628, Bibcode 2000A&A...361..614P
- ^ Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics 367 (2): 521–524. arXiv:astro-ph/0012289. Bibcode 2001A&A...367..521P. doi:10.1051/0004-6361:20000451.
- ^ Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series 85 (3): 1015–1019, Bibcode 1990A&AS...85.1015M
- ^ a b c d Hempel, M.; Schmitt, J. H. M. M. (2003). "High resolution spectroscopy of circumstellar material around A stars". Astronomy and Astrophysics 408 (3): 971–979. Bibcode 2003A&A...408..971H. doi:10.1051/0004-6361:20030946.
- ^ a b Royer, F.; Zorec, J.; Gómez, A. E. (February 2007). "Rotational velocities of A-type stars. III. Velocity distributions". Astronomy and Astrophysics 463 (2): 671–682. arXiv:astro-ph/0610785. Bibcode 2007A&A...463..671R. doi:10.1051/0004-6361:20065224.
- ^ a b Su, K. Y. L.; et al. (December 2006). "Debris Disk Evolution around A Stars". The Astrophysical Journal 653 (1): 675–689. arXiv:astro-ph/0608563. Bibcode 2006ApJ...653..675S. doi:10.1086/508649.
- ^ a b Song, Inseok; Caillault, J.-P.; Barrado y Navascués, David; Stauffer, John R. (January 2001). "Ages of A-Type Vega-like Stars from uvbyβ Photometry". The Astrophysical Journal 546 (1): 352–357. arXiv:astro-ph/0010102. Bibcode 2001ApJ...546..352S. doi:10.1086/318269.
- ^ "LTT 2656 – High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=LTT+2656. Retrieved 2009-09-10.
- ^ a b Goldin, A.; Makarov, V. V. (November 2007). "Astrometric Orbits for Hipparcos Stochastic Binaries". The Astrophysical Journal Supplement Series 173 (1): 137–142. Bibcode 2007ApJS..173..137G. doi:10.1086/520513.
- ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007). "X-ray emission from A-type stars". Astronomy and Astrophysics 475 (2): 677–684. Bibcode 2007A&A...475..677S. doi:10.1051/0004-6361:20077429.
- ^ Gliese, W. (1969). "Catalogue of Nearby Stars". Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg 22: 1. Bibcode 1969VeARI..22....1G.
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