Acrux
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Crux |
Pronunciation | /ˈeɪkrʌks/[citation needed] |
Right ascension | 12h 26m 35.89522s[1] |
Declination | −63° 05′ 56.7343″[1] |
Apparent magnitude (V) | 0.76[2] (1.33 + 1.75)[3] |
Characteristics | |
Spectral type | B0.5IV + B1V[4] |
B−V color index | −0.26[2] |
Variable type | |
Astrometry | |
Radial velocity (Rv) | −11.2 / −0.6[6] km/s |
Proper motion ( | RA: −35.83[1] mas/yr Dec.: −14.86[1] mas/yr |
Parallax ( | 10.13 ± 0.50 mas[1] |
Distance | 320 ± 20 ly (99 ± 5 pc) |
Absolute magnitude (MV) | −3.77[7] (−2.2 + −2.7[8]) |
Orbit[9] | |
Primary | |
Companion | |
Period (P) | 75.7794±0.0037 d |
Eccentricity (e) | 0.46±0.03 |
Periastron epoch (T) | 2,417,642.3±1.6 JD |
Argument of periastron ( (secondary) | 21±6° |
Semi-amplitude (K1) (primary) | 41.7±1.2 km/s |
Details | |
Mass | 17.80 + 6.05[3] M☉ |
Radius | 7.29 ± 0.34[5][a] R☉ |
Luminosity | 31,110+3,190 −2,910[5] L☉ |
Temperature | 28,840[5] K |
Rotational velocity (v sin i) | 124[5] km/s |
Mass | 15.52[3] M☉ |
Radius | 5.53[10] R☉ |
Luminosity | 16,000[11] L☉ |
Temperature | 28,000[12] K |
Rotational velocity (v sin i) | 200[12] km/s |
Age | 10.8[13] Myr |
Other designations | |
Database references | |
SIMBAD | |
Acrux is the brightest star in the southern constellation of Crux. It has the Bayer designation
To the naked eye Acrux appears as a single star, but it is actually a multiple star system containing six components. Through optical telescopes, Acrux appears as a triple star, whose two brightest components are visually separated by about 4 arcseconds and are known as Acrux A and Acrux B,
Nomenclature
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Deep_Crux_wide_field_with_fog.jpg/220px-Deep_Crux_wide_field_with_fog.jpg)
The historical name Acrux for
Since Acrux is at −63° declination, making it the southernmost first-magnitude star, it is only visible south of latitude 27° North. It barely rises from cities such as Miami, United States, or Karachi, Pakistan (both around 25°N) and not at all from New Orleans, United States, or Cairo, Egypt (both about 30°N). Because of Earth's axial precession, the star was visible to ancient Hindu astronomers in India who named it Tri-shanku. It was also visible to the ancient Romans and Greeks, who regarded it as part of the constellation of Centaurus.[23]
In Chinese,
This star is known as Estrela de Magalhães ("Star of Magellan") in Portuguese.[26]
Stellar properties
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/32/Acrux.png/220px-Acrux.png)
The two components,
Photometry with the TESS satellite has shown that one of the stars in the
Rizzuto and colleagues determined in 2011 that the
The cooler, less-luminous B-class star HR 4729 (HD 108250) lies 90 arcseconds away from triple star system
On 2 October 2008, the Cassini–Huygens spacecraft resolved three of the components (A, B and C) of the multiple star system as Saturn's disk occulted it.[33][34]
Separation (arcsec) |
Projected separation ( |
Orbital period |
Spectral type |
Mass (M☉) |
App. mag. (V) | ||||
---|---|---|---|---|---|---|---|---|---|
Acrux ABC | HR 4729 ABC (Acrux C & CP) [orbit note 1] |
2.1 | 220 | 930 years | M0V | 0.47 | 15.0 | ||
HR 4729 AB | HR 4729 A | 0.00046 | 0.048 | 1.225 days | B4V | 8.68 | 4.9 (combined) | ||
HR 4729 B | G?V | 0.97 | |||||||
Acrux AB ( [orbit note 1] |
4.4 | 460 | 1470 years | B1Vn | 15.52 | 1.8 | |||
Acrux Aa | 0.0094 | 0.99 | 75.8 days | B0.5IV | 17.80 | 1.3 (combined) | |||
Acrux ab | B7?V | 4.49 |
In culture
[edit]Acrux is represented in the flags of Australia, New Zealand, Samoa, and Papua New Guinea as one of five stars that compose the Southern Cross. It is also featured in the flag of Brazil, along with 26 other stars, each of which represents a state; Acrux represents the state of São Paulo.[35] As of 2015, it is also represented on the cover of the Brazilian passport.
The Brazilian oceanographic research vessel Alpha Crucis is named after the star.
See also
[edit]Notes
[edit]- ^ Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
- .
References
[edit]- ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600
- ^ a b Corben, P. M. (1966). "Photoelectric magnitudes and colours for bright southern stars". Monthly Notes of the Astron. Soc. Southern Africa. 25: 44. Bibcode:1966MNSSA..25...44C.
- ^ a b c d Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124 (1): 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181. ISSN 0365-0138.
- ^ Houk, Nancy (1979), "Michigan catalogue of two-dimensional spectral types for the HD stars", Ann Arbor: Dept. Of Astronomy, 1, Bibcode:1978mcts.book.....H
- ^ a b c d e f Sharma, Awshesh N.; Bedding, Timothy R.; Saio, Hideyuki; White, Timothy R. (2022). "Pulsating B stars in the Scorpius–Centaurus Association with TESS". Monthly Notices of the Royal Astronomical Society. 515 (1): 828–840. arXiv:2203.02582. Bibcode:2022MNRAS.515..828S. doi:10.1093/mnras/stac1816.
- ^ Wilson, Ralph Elmer (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
- ^ Kaltcheva, N. T.; Golev, V. K.; Moran, K. (2014). "Massive stellar content of the Galactic supershell GSH 305+01-24". Astronomy & Astrophysics. 562: A69. arXiv:1312.5592. Bibcode:2014A&A...562A..69K. doi:10.1051/0004-6361/201321454. S2CID 54222753.
- ^ Van De Kamp, Peter (1953). "The Twenty Brightest Stars". Publications of the Astronomical Society of the Pacific. 65 (382): 30. Bibcode:1953PASP...65...30V. doi:10.1086/126523.
- ^ Thackeray, A. D.; Wegner, G. (April 1980), "An improved spectroscopic orbit for
α 1 Crucis", Monthly Notices of the Royal Astronomical Society, 191 (2): 217–220, Bibcode:1980MNRAS.191..217T, doi:10.1093/mnras/191.2.217 - ^ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3 ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
The angular diameter used (0.52 milliarcseconds) is from CADARS. Distance (99 parsecs) is from Hipparcos.
- ^ a b c d Kaler, James B. (2002). "Acrux". The Hundred Greatest Stars. pp. 4–5. doi:10.1007/0-387-21625-1_2. ISBN 978-0-387-95436-3.
- ^ a b Dravins, Dainis; Jensen, Hannes; Lebohec, Stephan; Nuñez, Paul D. (2010). "Stellar intensity interferometry: Astrophysical targets for sub-milliarcsecond imaging". Proceedings of the SPIE. Optical and Infrared Interferometry II. 7734: 77340A. arXiv:1009.5815. Bibcode:2010SPIE.7734E..0AD. doi:10.1117/12.856394. S2CID 55641060.
- ^ 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): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
- ^ Bordeleau, André G. (12 August 2013). "Federative Republic of Brazil: Constellations in the Breeze". Flags of the Night Sky. New York: Springer. pp. 1–72. doi:10.1007/978-1-4614-0929-8_1. ISBN 978-1-4614-0928-1.
- ^ Perryman, Michael (2010), The Making of History's Greatest Star Map, Astronomers' Universe, Heidelberg: Springer-Verlag, Bibcode:2010mhgs.book.....P, doi:10.1007/978-3-642-11602-5, ISBN 978-3-642-11601-8
- ^ https://cfah.org.za/outreach/crux/
- ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
- ^ a b "I
AU Catalog of Star Names". Retrieved 21 November 2016. - ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
- ^ Memoirs of the Rev. Walter M. Lowrie: missionary to China (1849), p. 93. Described as an "Americanism" in The Geographical Journal, vol. 92, Royal Geographical Society, 1938.
- ^ "I
AU Working Group on Star Names (WGSN)". Retrieved 22 May 2016. - ^ "Bulletin of the I
AU Working Group on Star Names, No. 2" (PDF). Retrieved 12 October 2016. - ^ Richard Hinckley Allen, Star Names: Their Lore and Meaning, Dover Books, 1963.
- ^ (in Chinese)
中國 星座 神話 , written by陳 久金 . Published by台灣 書房 出版 有限 公司 , 2005, ISBN 978-986-7332-25-7. - ^ (in Chinese)
香港 太 空 館 -研究 資源 -亮 星 中 英 對照 表 Archived 2010-09-03 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010. - ^ Silva, Guilherme Marques dos Santos; Ribas, Felipe Braga; Freitas, Mário Sérgio Teixeira de (2008). "Transformação de coordenadas aplicada à construção da maquete tridimensional de uma constelação". Revista Brasileira de Ensino de Física. 30: 1306.1–1306.7. doi:10.1590/S1806-11172008000100007.
- ^ Nomoto, K. (1984). "Evolution of 8-10 solar mass stars toward electron capture supernovae. I - Formation of electron-degenerate O + NE + MG cores". Astrophysical Journal. 277: 791. Bibcode:1984ApJ...277..791N. doi:10.1086/161749.
- ^ S. E. Woosley, Alexander Heger (May 25, 2015). "The Remarkable Deaths of 9 - 11 Solar Mass Stars". Astrophysics. 810 (1): 34. arXiv:1505.06712. Bibcode:2015ApJ...810...34W. doi:10.1088/0004-637X/810/1/34. S2CID 119163256.
- ^ Rizzuto, Aaron; Ireland, Michael; Robertson, J. G. (October 2011), "Multidimensional Bayesian membership analysis of the Sco OB2 moving group", Monthly Notices of the Royal Astronomical Society, 416 (4): 3108–3117, arXiv:1106.2857, Bibcode:2011MNRAS.416.3108R, doi:10.1111/j.1365-2966.2011.19256.x, S2CID 54510608.
- ^ Shatsky, N.; Tokovinin, A. (2002). "The mass ratio distribution of B-type visual binaries in the Sco OB2 association". Astronomy and Astrophysics. 382: 92–103. arXiv:astro-ph/0109456. Bibcode:2002A&A...382...92S. doi:10.1051/0004-6361:20011542. S2CID 16697655.
- ^ Eggleton, Peter; Tokovinin, A. (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. S2CID 14878976.
- ^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
- ^ "Cassini raw image". NASA/JPL/Space Science Institute. Retrieved 2017-10-31.
- ^ Cassini "Kodak Moments" - Unmanned Spaceflight.com. Retrieved 2008-10-21
- ^ "Astronomy of the Brazilian Flag". FOTW Flags Of The World website.
External links
[edit]- http://jumk.de/astronomie/big-stars/acrux.shtml
- http://www.daviddarling.info/encyclopedia/A/Acrux.html