Theta1 Orionis D
Theta1 Orionis D (θ1 Orionis D) is a member of the Trapezium open cluster that lies within the Orion Nebula. It is a B class blue main sequence star with several faint companions.
 Theta1 Orionis D and companions in the Trapezium cluster | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 17.19248s[1] |
| Declination | −05° 23′ 14.4551″[1] |
| Apparent magnitude (V) | 6.70[2] |
| Characteristics | |
| Spectral type | B1.5 Vp[3] |
| U−B color index | −0.71[2] |
| B−V color index | +0.09[2] |
| Astrometry | |
| Radial velocity (Rv) | +32.4[4] km/s |
| Proper motion (μ) | RA: −7.11[1] mas/yr Dec.: 8.29[1] mas/yr |
| Parallax (π) | −27.24 ± 8.21[1] mas |
| Distance | 450 ± 50[5] pc |
| Absolute magnitude (MV) | −3.3[5] |
| Details | |
| Mass | 18 ± 6[5] M☉ |
| Radius | 5.6 ± 0.8[5] R☉ |
| Luminosity | 29,500[5] L☉ |
| Surface gravity (log g) | 4.2 ± 0.1[5] cgs |
| Temperature | 32,000 ± 1,000[5] K |
| Rotational velocity (v sin i) | 49.0 ± 0.9[5] km/s |
| Age | 2.5 ± 0.5[5] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
θ1 Orionis consists of multiple components, primarily the four stars of the Trapezium cluster (A, B, C, and D) all within one arc-minute of each other. θ2 Orionis is a more distant grouping of three main stars plus several fainter companions, 1-2 arc-minutes from θ1.
θ1 D itself has a faint optical companion 1.4" away and a spectroscopic companion in a 40-day orbit. Infrared Optical Telescope Array observations suggest another companion at 18.6 mas.[6]
References
- 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
- 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.
- Levenhagen, R. S.; Leister, N. V. (2006). "Spectroscopic analysis of southern B and Be stars". Monthly Notices of the Royal Astronomical Society. 371: 252. arXiv:astro-ph/0606149. Bibcode:2006MNRAS.371..252L. doi:10.1111/j.1365-2966.2006.10655.x.
- Olivares, J.; Sánchez, L. J.; Ruelas-Mayorga, A.; Allen, C.; Costero, R.; Poveda, A. (2013). "Kinematics of the Orion Trapezium Based on Diffracto-Astrometry and Historical Data". The Astronomical Journal. 146 (5): 106. arXiv:1310.0769. Bibcode:2013AJ....146..106O. doi:10.1088/0004-6256/146/5/106.
- Simón-Díaz, S.; Herrero, A.; Esteban, C.; Najarro, F. (2006). "Detailed spectroscopic analysis of the Trapezium cluster stars inside the Orion nebula". Astronomy and Astrophysics. 448 (1): 351–366. arXiv:astro-ph/0510288. Bibcode:2006A&A...448..351S. doi:10.1051/0004-6361:20053066. ISSN 0004-6361.
- 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. arXiv:1301.3045. Bibcode:2013A&A...550A..82G. doi:10.1051/0004-6361/201220192.
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