Astronomy:Theta1 Orionis A
280px Trapezium stars | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 15.84743s[1] |
| Declination | −05° 23′ 14.3441″[1] |
| Apparent magnitude (V) | 6.72 - 7.65[2] |
| Characteristics | |
| Spectral type | B0.5V[3] + G[4] + F PMS[5] |
| Variable type | Algol[2] |
| Astrometry | |
| Radial velocity (Rv) | 32.354±0.062[4] km/s |
| Proper motion (μ) | RA: 4.81±0.10[6] mas/yr Dec.: −2.53±0.12[6] mas/yr |
| Parallax (π) | 2.626 ± 0.100[6] mas |
| Distance | 1,272.0 ± 6.5 ly (390±2 pc) |
| Absolute magnitude (MV) | −2.80[3] |
| Orbit[4] | |
| Primary | A1 |
| Companion | A3 |
| Period (P) | 65.433300±0.000019 days |
| Semi-major axis (a) | 178.56 ± 0.45 R☉ (0.8304 ± 0.0021 astronomical unit|au) |
| Eccentricity (e) | 0.64383±0.00029 |
| Inclination (i) | 87.090±0.014° |
| Periastron epoch (T) | 2,459,441.257±0.016 HJD |
| Argument of periastron (ω) (secondary) | 177.88±0.06° |
| Semi-amplitude (K1) (primary) | 28.499±0.082 km/s |
| Semi-amplitude (K2) (secondary) | 151.43±0.76 km/s |
| Details[4] | |
| A1 | |
| Mass | 15.01±0.32 M☉ |
| Radius | 4.20±0.05 R☉ |
| Luminosity | 15,800+3,200 −2,700 L☉ |
| Surface gravity (log g) | 4.37±0.01 cgs |
| Temperature | 30,500±800 K |
| Age | 0.7 Myr |
| A3 | |
| Mass | 2.825±0.145 M☉ |
| Radius | 6.415±0.055 R☉ |
| Luminosity | 54+11 −9 L☉ |
| Surface gravity (log g) | 3.28±0.04 cgs |
| Temperature | 5,550±500 K |
| Age | 0.7 Myr |
| A2 | |
| Mass | 4[7][5] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Theta1 Orionis A (θ1 Ori A) is a trinary star in the constellation Orion. The system consists of an close pair of eclipsing stars orbited by a visual companion farther away. Its apparent magnitude range is 6.72 to 7.65 with a period of 65.432 days. It is one of the main stars in The Trapezium in Orion, along with B, C, and D, as well as the fainter E.
Variability
θ1 Orionis A varies in brightness, showing dips from magnitude 6.72 to 7.65 every 65.432 days. These are caused by eclipses of the central pair. θ1 Orionis A has been assigned the variable star designation V1016 Orionis.[2]
System
θ1 Orionis A1 and θ1 Orionis A3 form an eclipsing binary system, where only the primary is detected in the spectrum.[10][11] The components orbit around each other with an orbital period of roughly 65.4 days, following a highly-eccentric path with a semi-major axis of 0.8304 ± 0.0021 au and an eccentricity of 0.644. The primary is an B0.5V star with a temperature of 30,500 K, 15 times the mass of the Sun, 4.2 times the Sun's radius, and a luminosity 16,000 times solar.[4] The secondary has been proposed to be a T Tauri star, possibly of spectral class A,[12][11] but later confirmed to be of spectral class G with a temperature of 5,600±500 K. It has a mass 2.8 times solar and an inflated radius of 6.4 times that of the Sun, radiating a luminosity 54 times brighter than the Sun's.[4]
θ1 Orionis A2 is an F-type pre-main-sequence star, 1.63 fainter than the inner pair in the K band and with an estimated mass of 4 solar masses. It was proven to be gravitationally bound to the system in 2018 using long-term astrometric measurements. Its separation from the inner pair has changed from 0.227" in 1995 to 0.193" in late 2011. At the system's distance, the angular separations correspond to a projected separation of 90–100 astronomical unit|AU. Its orbital period has been determined at 214 years.[5]
References
- ↑ 1.0 1.1 Kounkel, Marina; Hartmann, Lee; Loinard, Laurent; Mioduszewski, Amy J.; Dzib, Sergio A.; Ortiz-León, Gisela N.; Rodríguez, Luis F.; Pech, Gerardo et al. (2014). "The Gould's Belt Very Large Array Survey. III. The Orion Region". The Astrophysical Journal 790 (1): 49. doi:10.1088/0004-637X/790/1/49. Bibcode: 2014ApJ...790...49K.
- ↑ 2.0 2.1 2.2 Samus, N. N. 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. Bibcode: 2009yCat....102025S.
- ↑ 3.0 3.1 Nieva, María-Fernanda; Przybilla, Norbert (2014). "Fundamental properties of nearby single early B-type stars". Astronomy & Astrophysics 566: A7. doi:10.1051/0004-6361/201423373. Bibcode: 2014A&A...566A...7N.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Sowell, James R.; Fekel, Francis C.; Henry, Gregory W.; Williamson, Michael H.; Armstrong, James D.; Aipa, Ryan; Stino, Martino (2026-07-13). "The Properties of V1016 Orionis, the Eclipsing Binary in the Trapezium System θ1 Orionis A". The Astronomical Journal 172 (2): 78. doi:10.3847/1538-3881/ae7c7b. ISSN 0004-6256.
- ↑ 5.0 5.1 5.2 GRAVITY Collaboration; Karl, Martina; Pfuhl, Oliver; Eisenhauer, Frank; Genzel, Reinhard; Grellmann, Rebekka; Habibi, Maryam; Abuter, Roberto et al. (2018-12-01). "Multiple star systems in the Orion nebula". Astronomy and Astrophysics 620: A116. doi:10.1051/0004-6361/201833575. ISSN 0004-6361. Bibcode: 2018A&A...620A.116G.
- ↑ 6.0 6.1 6.2 Kounkel, Marina et al. (2017). "The Gould's Belt Distances Survey (GOBELINS) II. Distances and Structure toward the Orion Molecular Clouds". The Astrophysical Journal 834 (2): 142. doi:10.3847/1538-4357/834/2/142. Bibcode: 2017ApJ...834..142K.
- ↑ Grellmann, R.; Preibisch, T.; Ratzka, T.; Kraus, S.; Helminiak, K. G.; Zinnecker, H. (2013). "The multiplicity of massive stars in the Orion Nebula Cluster as seen with long-baseline interferometry". Astronomy & Astrophysics 550: A82. doi:10.1051/0004-6361/201220192. Bibcode: 2013A&A...550A..82G.
- ↑ "Download Data". AAVSO. https://www.aavso.org/data-download.
- ↑ Lloyd, C.; Stickland, D. J. (November 1999). "The Nature of the Bright Early-Type Eclipsing Binary Theta 1 Ori A = V1016 Orionis". Information Bulletin on Variable Stars 4809: 1. Bibcode: 1999IBVS.4809....1L. https://ui.adsabs.harvard.edu/abs/1999IBVS.4809....1L. Retrieved 8 February 2022.
- ↑ Bossi, M.; Gaspani, A.; Scardia, M.; Tadini, M. (1989). "Orionis A - A pre-main sequence low Q binary system?". Astronomy and Astrophysics 222: 117. Bibcode: 1989A&A...222..117B.
- ↑ 11.0 11.1 Vitrichenko, E. A.; Klochkova, V. G. (2000). "A Spectroscopic Study of V1016 Ori". Astronomy Letters 26 (2): 104. doi:10.1134/1.20373. Bibcode: 2000AstL...26..104V.
- ↑ Petr, Monika G.; Coudé Du Foresto, Vincent; Beckwith, Steven V. W.; Richichi, Andrea; McCaughrean, Mark J. (1998). "Binary Stars in the Orion Trapezium Cluster Core". The Astrophysical Journal 500 (2): 825. doi:10.1086/305751. Bibcode: 1998ApJ...500..825P.
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External links
- "Trapezium (Theta1 Orionis)". The Worlds of David Darling. http://www.daviddarling.info/encyclopedia/T/Trapezium.html. Retrieved 31 July 2014.
- "Theta-1 Orionis". http://stars.astro.illinois.edu/sow/theta1ori.html. Retrieved 31 July 2014.
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