Ahernar
  | |
| Položaj na nebu Epoha J2000 Ravnodnevnica J2000 | |
|---|---|
| Sazvežđe | Eridan |
| Rektascenzija | 01h 37m 42.84548s[1] |
| Deklinacija | –57° 14′ 12.3101″[1] |
| Prividna magnituda (V) | 0.40 - 0.46[2] |
| Karakteristike | |
| Spektralni tip | B6 Vep[3] |
| U−B indeks boja | −0.66[4] |
| B−V indeks boja | −0.16[4] |
| Varijabilni tip | Be[2] |
| Astrometrija | |
| Radijalna brzina (Rv) | +16[5] km/s |
| Sopstveno kretanje (μ) | RA: 87.00 ± 0.58[1] mas/g Dek.: −38.24 ± 0.50[1] mas/g |
| Paralaksa (π) | 23.39 ± 0.57[1] mas |
| Rastojanje | 139 ± 3 ly (43 ± 1 ps) |
| Apsolutna magnituda (MV) | –1.46[6] |
| Detalji | |
| Masa | 6.7[7] M☉ |
| Poluprečnik | 7.3 × 11.4[8] R☉ |
| Luminoznost | 3,150[8] L☉ |
| Površinska gravitacija (log g) | 3.5[9] cgs |
| Temperatura | ~15,000[9] K |
| Rotaciona brzina (v sin i) | 250[9] km/s |
| Starost | 37.3[10] Myr |
| Druge oznake | |
| Referentne baze podataka | |
| SIMBAD | data |
Ahernar[12] je primarna (ili 'A') komponenta[13] binarnog sistema[7] označenog sa Alfa Eridani (α Eridani, skraćeno Alfa Eri, α Eri), koji je najsjajnija zvezda u sazvežđu Eridan, i deveta najsjajnija zvezda noćnog neba. Dve komponente su označene kao Alfa Eridani A (primarna) i B (sekundarna, takođe poznata pod nazivom Ahernar B). Kao što je utvrđeno pomoću astromerskog satelita Hiparkos,[14][15] ova zvezda je udaljena oko 139 ly (43 pc) od Sunca.[1]
Od deset naizgled najsjajnijih zvezda na noćnom nebu,[nb 1] Alfa Eridani je najtoplija i najviše plave boje, zbog toga što je Ahernar spektralnog tipa B. Ahernar ima neobično veliku brzinu rotacije, zbog čega poprima spljošteni u oblik. Sekundarna zvezda je manja, spektralnog tipa A, i orbitira Ahernar na udaljenosti od oko 12 astronomskih jedinica (AU).
Napomene[уреди | уреди извор]
- ^ The ten brightest stars in the nighttime sky in terms of apparent magnitude are, from brightest to least brightest, Sirius, Canopus, Alpha Centauri, Arcturus, Vega, Capella, Rigel, Procyon, Achernar and Betelgeuse
Reference[уреди | уреди извор]
- ^ а б в г д ђ van Leeuwen, F. (novembar 2007). „Validation of the new Hipparcos reduction”. Astronomy and Astrophysics. 474 (2): 653—664. Bibcode:2007A&A...474..653V. arXiv:0708.1752
. doi:10.1051/0004-6361:20078357.
- ^ а б Samus, N. N.; Durlevich, O. V.; et al. (2009). „VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)”. VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: 02025. Bibcode:2009yCat....102025S.
- ^ Nazé, Y. (novembar 2009). „Hot stars observed by XMM-Newton. I. The catalog and the properties of OB stars”. Astronomy and Astrophysics. 506 (2): 1055—1064. Bibcode:2009A&A...506.1055N. arXiv:0908.1461 . doi:10.1051/0004-6361/200912659.
- ^ а б Ducati, J. R. (2002). „VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system”. CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
- ^ Evans, D. S. (20—24. 6. 1966). „The Revision of the General Catalogue of Radial Velocities”. Ур.: Batten, Alan Henry; Heard, 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.
- ^ Moujtahid, A.; Zorec, J. (2000). „The Visual Absolute Magnitude of the Central Objects in Be Stars”. The be Phenomenon in Early-Type Stars. 214: 55. Bibcode:2000ASPC..214...55M.
- ^ а б Kervella, P.; Domiciano de Souza, A.; Bendjoya, Ph. (jun 2008). „The close-in companion of the fast rotating Be star Achernar”. Astronomy and Astrophysics. 484 (1): L13—L16. Bibcode:2008A&A...484L..13K. arXiv:0804.3465 . doi:10.1051/0004-6361:200809765.
- ^ а б Carciofi, A. C.; et al. (mart 2008). „On the Determination of the Rotational Oblateness of Achernar”. The Astrophysical Journal. 676 (1): L41—L44. Bibcode:2008ApJ...676L..41C. arXiv:0801.4901 . doi:10.1086/586895.
- ^ а б в Kervella, P.; et al. (januar 2009). „The environment of the fast rotating star Achernar. II. Thermal infrared interferometry with VLTI/MIDI”. Astronomy and Astrophysics. 493 (3): L53—L56. Bibcode:2009A&A...493L..53K. arXiv:0812.2531 . doi:10.1051/0004-6361:200810980.
- ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011). „A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun”. Monthly Notices of the Royal Astronomical Society. 410 (1): 190. Bibcode:2011MNRAS.410..190T. arXiv:1007.4883 . doi:10.1111/j.1365-2966.2010.17434.x.
- ^ „Achernar -- Be Star”. SIMBAD. Centre de Données astronomiques de Strasbourg. Приступљено 16. 2. 2010.
- ^ „Achernar”. Merriam-Webster Dictionary.
- ^ „Naming Stars”. IAU.org. Приступљено 16. 12. 2017.
- ^ Perryman, M. A. C.; Lindegren, L.; Kovalevsky, J.; et al. (jul 1997). „The Hipparcos Catalogue”. Astronomy and Astrophysics. 323: L49—L52. Bibcode:1997A&A...323L..49P.
- ^ Perryman, Michael (2010). The Making of History's Greatest Star Map. The Making of History's Greatest Star Map. Astronomers’ Universe. Heidelberg: Springer-Verlag. Bibcode:2010mhgs.book.....P. ISBN 978-3-642-11601-8. doi:10.1007/978-3-642-11602-5.
Literatura[уреди | уреди извор]
- Lovekin, C. C.; Deupree, R. G.; Short, C. I. (2006). „Surface Temperature and Synthetic Spectral Energy Distributions for Rotationally Deformed Stars”. The Astrophysical Journal. 643 (1): 460—470. Bibcode:2006ApJ...643..460L. arXiv:astro-ph/0602084 . doi:10.1086/501492.
- Carciofi, A. C.; et al. (decembar 2007). „Achernar: Rapid Polarization Variability as Evidence of Photospheric and Circumstellar Activity”. The Astrophysical Journal. 671 (1): L49—L52. Bibcode:2007ApJ...671L..49C. arXiv:0710.4163 . doi:10.1086/524772.
