Astronomy:S Ori 70
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 38m 10.10s[1] |
| Declination | −02° 36′ 00.0″[1] |
| Characteristics | |
| Spectral type | T6[2][3] |
| Apparent magnitude (H) | 20.07[4] |
| Astrometry | |
| Proper motion (μ) | RA: 10[1] mas/yr Dec.: 5[1] mas/yr |
| Distance | 1,150[5] ly (352[4] pc) |
| Details | |
| Mass | 3[6] MJup |
| Surface gravity (log g) | 3.5[6] cgs |
| Age | 3[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
S Ori 70 or S Ori J053810.1-023626 is a mid-T type astronomical object in the foreground of the σ Orionis cluster, which is approximately 1,150 light-years from Earth. It was discovered on November 24, 2002 by M. R. Zapatero-Osorio and E. L. Martin's team at the Roque de los Muchachos Observatory. It has yet to be determined if it is a field brown dwarf or a 3-million-year-old planet that is part of a cluster. Near-infrared spectroscopy images taken three years after its discovery led to the first motion measurements for the object. Its behavior is significantly different from what may be expected; it was further described as either a low-gravity atmosphere or an atmosphere with metallicity. The object's small proper motion suggests that it is further away than expected if it were a single field T dwarf.
Discovery
The σ Orionis open cluster has been the focus of Osorio's team observations due to the age of the cluster (approximately 3 to 8 million years). The cluster also has low extinction, its distance is convenient, and it is observed to be rich and dense. Using the 4.2-meter (170-inch) William Herschel Telescope in a pencil-beam deep mini-survey measuring 55 square minutes of arc at a sensitivity of 21 magnitudes in the J and H Bands[6] allowed the team to find S Ori 70. The raw data collected was reduced to IRAF (an acronym for Image Reduction and Analysis Facility), a standard technique used with near-infrared images; after subtracting the sky background and dark current, an extracted object spectrum was derived. It was the faintest and coolest member found in the cluster and was named S Ori 70.
Argument of the initial study
Adam J. Burgasser[9][10] examined the claims of Osorio's T-type brown dwarf discovery and its spectroscopically verified low-mass. A comparison of the J band spectrum between S Ori 70 and other field objects was done. The J band spectrum revealed a distinct triangular-shaped spectral morphology which was previously explained by Zapatero-Osorio and Martín was due to the surface's low gravity. In order to see if similar discrepancies occurred in the T dwarf's behavior, Burgasser's team compared data from the claims of Osorio to that of standard COND models. Identical wavelength scales interpolated through both empirical and model spectra were Gaussian smoothed; this showed that best-fit spectral models can yield skewed gravities for late-type field T dwarfs which resulted in the underestimation of age and mass. Burgasser concluded that S Ori 70 is not a member of the Sigma Ori cluster but is rather a foreground field brown dwarf. Further study of the object suggest that the low gravity was not from the field T dwarf but rather a nearby background star.[9] As of 2009 no direct scientific data have dispelled nor confirmed either conclusion.
It could be the first "free floating" non-stellar planet discovered[5] with a mass of 3 MJ, but needs confirmation.
See also
- List of exoplanet firsts
- S Ori 52
References
- ↑ 1.0 1.1 1.2 1.3 Faherty, Jacqueline K.; Burgasser, Adam J.; Cruz, Kelle L.; Shara, Michael M.; Walter, Frederick M.; Gelino, Christopher R. (2009). "The Brown Dwarf Kinematics Project I. Proper Motions and Tangential Velocities for a Large Sample of Late-Type M, L, and T Dwarfs". The Astronomical Journal 137 (1): 1. doi:10.1088/0004-6256/137/1/1. Bibcode: 2009AJ....137....1F.
- ↑ Zapatero-Osorio, María Rosa; Béjar, V. J. S.; Bihain, G.; Martín, Eduardo L.; Rebolo, Rafael; Villó-Pérez, I.; Díaz-Sánchez, A.; Pérez Garrido, A. et al. (2008). "New constraints on the membership of the T dwarf S Ori 70 in theσ Orionis cluster". Astronomy & Astrophysics 477 (3): 895–900. doi:10.1051/0004-6361:20078600. Bibcode: 2008A&A...477..895Z.
- ↑ Martín, Eduardo L.; Zapatero-Osorio, María Rosa (2003). "Spectroscopic Estimate of Surface Gravity for a Planetary Member in the σ Orionis Cluster". The Astrophysical Journal 593 (2): L113. doi:10.1086/378313. Bibcode: 2003ApJ...593L.113M.
- ↑ 4.0 4.1 Peña Ramírez, K.; Zapatero-Osorio, María Rosa; Béjar, V. J. S.; Martin, Eduardo L.; Rebolo, Rafael; Villo-Perez, I.; Diaz-Sanchez, A.; Perez-Garrido, A. et al. (2015). "Characterization of the known T-type dwarfs towards the σ Orionis cluster". Astronomy and Astrophysics 574: A118. doi:10.1051/0004-6361/201424816. Bibcode: 2015A&A...574A.118P.
- ↑ 5.0 5.1 "Mysterious Object Might be First Extrasolar Planet Photographed". Silver Star Academy. http://www.silverstar-academy.com/Archive/Astral/Kuiper_Objects/Object_SOri70/object_sori70.htm. Retrieved 2010-02-08.
- ↑ 6.0 6.1 6.2 6.3 Martín, Eduardo L. (2004). "S Ori 70: Still a strong cluster planet candidate". arXiv:astro-ph/0410678.
- ↑ Kenyon, M. J.; Jeffries, R. D.; Naylor, Tim; Oliveira, J. M.; Maxted, P. F. L. (2005). "Membership, binarity and accretion among very low-mass stars and brown dwarfs of the σ Orionis cluster". Monthly Notices of the Royal Astronomical Society 356 (1): 89. doi:10.1111/j.1365-2966.2004.08455.x. Bibcode: 2005MNRAS.356...89K.
- ↑ Burgasser, Adam J.; Geballe, T. R.; Leggett, S. K.; Kirkpatrick, J. Davy; Golimowski, David A. (2006). "A Unified Near-Infrared Spectral Classification Scheme for T Dwarfs". The Astrophysical Journal 637 (2): 1067–1093. doi:10.1086/498563. Bibcode: 2006ApJ...637.1067B.
- ↑ 9.0 9.1 Burgasser, Adam J.; Kirkpatrick, J. Davy; McGovern, Mark R.; McLean, Ian S.; Prato, L.; Reid, I. Neill (2004). "S Orionis 70: Just a Foreground Field Brown Dwarf?". The Astrophysical Journal 604 (2): 827–831. doi:10.1086/382129. Bibcode: 2004ApJ...604..827B.
- ↑ "T dwarfs". MIT.edu. http://web.mit.edu/ajb/www/tdwarf/. Retrieved 2010-02-08.
 |  |
