  | |
| Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 18h 49m 34.99649s [1] |
| Declination | −43° 26′ 02.7522″ [1] |
| Apparent magnitude (V) | 5.59±0.01 [2] |
| Characteristics | |
| Evolutionary stage | main sequence star [3] |
| Spectral type | B9 IV [4] |
| B−V color index | −0.08 [5] |
| Astrometry | |
| Radial velocity (Rv) | −23.0±4.3 [6] km/s |
| Proper motion (μ) |
RA: −2.963
mas/
yr
[1] Dec.: −25.374 mas/ yr [1] |
| Parallax (π) | 4.25 ± 0.1158 mas [1] |
| Distance | 770 ± 20
ly (235 ± 6 pc) |
| Absolute magnitude (MV) | −0.24 [7] |
| Details | |
| Mass | 3.23±0.08 [3] M☉ |
| Radius | 5.82±0.31 [8] R☉ |
| Luminosity | 171+20 −18 [3] L☉ |
| Surface gravity (log g) | 3.47 [9] cgs |
| Temperature | 10,940±255 [3] K |
| Metallicity [Fe/H] | +0.06 [9] dex |
| Rotational velocity (v sin i) | 30 [10] km/s |
| Age | 213 [11] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta2 Coronae Australis (Eta2 CrA), Latinized from η2 Coronae Australis, is a solitary star [14] located in the southern constellation of Corona Australis. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.59. [2] Gaia DR3 parallax measurements imply a distance of 770 light years from the Solar System, [1] but it is drifting closer with a radial velocity of −23 km/s. [6] At its current distance Eta2 CrA's brightness is diminished by 0.27 magnitudes due to stellar extinction from interstellar dust [15] and it has an absolute magnitude of −0.24. [7]
This object has a stellar classification of B9 IV, [4] indicating that is a slightly evolved a B-type subgiant star. However, Zorec & Royer (2012) model it to be a dwarf star that has completed 80.4% of its main sequence lifetime. [3] It is estimated to be 213 million years old [11] and it has a mass that is 3.23 times that of the Sun. [3] The star is radiating 171 times the luminosity of the Sun [3] from its photosphere 5.82 times the radius of the Sun [8] at an effective temperature of 10,940 K. [3] Eta2 CrA has a near-solar metallicity at [Fe/H] = +0.06 [9] and spins modestly with a projected rotational velocity of 30 km/s. [10] Some earlier catalogues listed the object as a chemically peculiar star but that status is now considered to be doubtful. [16]
Sources
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211. Bibcode: 2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode: 2000A&A...355L..27H. ISSN 0004-6361. S2CID 17128864.
- ^ a b c d e f g h Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars IV: Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv: 1201.2052. Bibcode: 2012A&A...537A.120Z. doi: 10.1051/0004-6361/201117691. eISSN 1432-0746. ISSN 0004-6361. S2CID 55586789.
- ^ a b Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. Vol. 2. Bibcode: 1978mcts.book.....H.
- ^ Corben, P. M.; Stoy, R. H. (1968). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of Southern Africa. 27: 11. Bibcode: 1968MNSSA..27...11C.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv: 1606.08053. Bibcode: 2006AstL...32..759G. doi: 10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
- ^ a b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971. Bibcode: 2012AstL...38..331A. doi: 10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
- ^ a b Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants. Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics. 426 (1): 297–307. arXiv: astro-ph/0404180. Bibcode: 2004A&A...426..297K. doi: 10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361. S2CID 6077801.
- ^ a b c Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv: 1904.11302. Bibcode: 2019A&A...628A..94A. doi: 10.1051/0004-6361/201935765. eISSN 1432-0746. ISSN 0004-6361. S2CID 131780028.
- ^ a b Levato, Hugo; Grosso, Mónica (June 2004). "New Projected Rotational Velocities of All Southern B-type Stars of the Bright Star Catalogue". Symposium - International Astronomical Union. 215: 51–52. Bibcode: 2004IAUS..215...51L. doi: 10.1017/S0074180900195191. ISSN 0074-1809.
- ^ a b Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv: 1606.09028, Bibcode: 2012AstL...38..694G, doi: 10.1134/S1063773712110035, S2CID 119108982.
- ^ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode: 1879RNAO....1.....G.
- ^ "Eta02 CrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved March 8, 2023.
- ^ Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv: 0806.2878. Bibcode: 2008MNRAS.389..869E. doi: 10.1111/j.1365-2966.2008.13596.x. eISSN 1365-2966. ISSN 0035-8711. S2CID 14878976.
- ^ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv: 1709.01160. Bibcode: 2017MNRAS.472.3805G. doi: 10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
- ^ Renson, P.; Manfroid, J. (19 March 2009). "Catalogue of Ap, HgMn and Am stars". Astronomy & Astrophysics. 498 (3): 961–966. Bibcode: 2009A&A...498..961R. doi: 10.1051/0004-6361/200810788. eISSN 1432-0746. ISSN 0004-6361. S2CID 55849045.
| |
| Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 18h 49m 34.99649s [1] |
| Declination | −43° 26′ 02.7522″ [1] |
| Apparent magnitude (V) | 5.59±0.01 [2] |
| Characteristics | |
| Evolutionary stage | main sequence star [3] |
| Spectral type | B9 IV [4] |
| B−V color index | −0.08 [5] |
| Astrometry | |
| Radial velocity (Rv) | −23.0±4.3 [6] km/s |
| Proper motion (μ) |
RA: −2.963
mas/
yr
[1] Dec.: −25.374 mas/ yr [1] |
| Parallax (π) | 4.25 ± 0.1158 mas [1] |
| Distance | 770 ± 20
ly (235 ± 6 pc) |
| Absolute magnitude (MV) | −0.24 [7] |
| Details | |
| Mass | 3.23±0.08 [3] M☉ |
| Radius | 5.82±0.31 [8] R☉ |
| Luminosity | 171+20 −18 [3] L☉ |
| Surface gravity (log g) | 3.47 [9] cgs |
| Temperature | 10,940±255 [3] K |
| Metallicity [Fe/H] | +0.06 [9] dex |
| Rotational velocity (v sin i) | 30 [10] km/s |
| Age | 213 [11] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta2 Coronae Australis (Eta2 CrA), Latinized from η2 Coronae Australis, is a solitary star [14] located in the southern constellation of Corona Australis. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.59. [2] Gaia DR3 parallax measurements imply a distance of 770 light years from the Solar System, [1] but it is drifting closer with a radial velocity of −23 km/s. [6] At its current distance Eta2 CrA's brightness is diminished by 0.27 magnitudes due to stellar extinction from interstellar dust [15] and it has an absolute magnitude of −0.24. [7]
This object has a stellar classification of B9 IV, [4] indicating that is a slightly evolved a B-type subgiant star. However, Zorec & Royer (2012) model it to be a dwarf star that has completed 80.4% of its main sequence lifetime. [3] It is estimated to be 213 million years old [11] and it has a mass that is 3.23 times that of the Sun. [3] The star is radiating 171 times the luminosity of the Sun [3] from its photosphere 5.82 times the radius of the Sun [8] at an effective temperature of 10,940 K. [3] Eta2 CrA has a near-solar metallicity at [Fe/H] = +0.06 [9] and spins modestly with a projected rotational velocity of 30 km/s. [10] Some earlier catalogues listed the object as a chemically peculiar star but that status is now considered to be doubtful. [16]
Sources
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211. Bibcode: 2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode: 2000A&A...355L..27H. ISSN 0004-6361. S2CID 17128864.
- ^ a b c d e f g h Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars IV: Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv: 1201.2052. Bibcode: 2012A&A...537A.120Z. doi: 10.1051/0004-6361/201117691. eISSN 1432-0746. ISSN 0004-6361. S2CID 55586789.
- ^ a b Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. Vol. 2. Bibcode: 1978mcts.book.....H.
- ^ Corben, P. M.; Stoy, R. H. (1968). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of Southern Africa. 27: 11. Bibcode: 1968MNSSA..27...11C.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv: 1606.08053. Bibcode: 2006AstL...32..759G. doi: 10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
- ^ a b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971. Bibcode: 2012AstL...38..331A. doi: 10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
- ^ a b Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants. Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics. 426 (1): 297–307. arXiv: astro-ph/0404180. Bibcode: 2004A&A...426..297K. doi: 10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361. S2CID 6077801.
- ^ a b c Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv: 1904.11302. Bibcode: 2019A&A...628A..94A. doi: 10.1051/0004-6361/201935765. eISSN 1432-0746. ISSN 0004-6361. S2CID 131780028.
- ^ a b Levato, Hugo; Grosso, Mónica (June 2004). "New Projected Rotational Velocities of All Southern B-type Stars of the Bright Star Catalogue". Symposium - International Astronomical Union. 215: 51–52. Bibcode: 2004IAUS..215...51L. doi: 10.1017/S0074180900195191. ISSN 0074-1809.
- ^ a b Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv: 1606.09028, Bibcode: 2012AstL...38..694G, doi: 10.1134/S1063773712110035, S2CID 119108982.
- ^ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode: 1879RNAO....1.....G.
- ^ "Eta02 CrA". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved March 8, 2023.
- ^ Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv: 0806.2878. Bibcode: 2008MNRAS.389..869E. doi: 10.1111/j.1365-2966.2008.13596.x. eISSN 1365-2966. ISSN 0035-8711. S2CID 14878976.
- ^ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv: 1709.01160. Bibcode: 2017MNRAS.472.3805G. doi: 10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
- ^ Renson, P.; Manfroid, J. (19 March 2009). "Catalogue of Ap, HgMn and Am stars". Astronomy & Astrophysics. 498 (3): 961–966. Bibcode: 2009A&A...498..961R. doi: 10.1051/0004-6361/200810788. eISSN 1432-0746. ISSN 0004-6361. S2CID 55849045.