Astronomy:2MASS J12195156+3128497
Coordinates: 
12h 19m 51.56s, +31° 28′ 49.71″
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Coma Berenices |
| Right ascension | 12h 19m 51.561s[1] |
| Declination | +31° 28′ 49.714″[1] |
| Characteristics | |
| Spectral type | L8[2] |
| Apparent magnitude (J) | 15.913 ± 0.082[1] |
| Apparent magnitude (H) | 14.907 ± 0.074[1] |
| Apparent magnitude (K) | 14.305 ± 0.072[1] |
| Astrometry | |
| Radial velocity (Rv) | −19.0 ± 4.2[2] km/s |
| Proper motion (μ) | RA: –233.0 ± 23.7[3] mas/yr Dec.: –49.6 ± 14.7[3] mas/yr |
| Distance | 66.2 ± 9.8 ly (20.3 ± 3.0[4] pc) |
| Details[2] | |
| Mass | 0.047+0.022 −0.025 M☉ |
| Radius | 0.100+0.027 −0.013 R☉ |
| Surface gravity (log g) | 5.1 ± 0.5 cgs |
| Temperature | 1330 ± 140 K |
| Rotation | 1.14+0.03 −0.01 h |
| Rotational velocity (v sin i) | 79.0 ± 3.4 km/s |
| Age | 0.9+12.8 −0.8 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
2MASS J12195156+3128497 (abbreviated to 2MASS J1219+3128) is a rapidly-rotating brown dwarf of spectral class L8, located in the constellation Coma Berenices about 66 light-years from Earth. With a photometrically measured rotation period of 1.14 hours, it is one of the fastest-rotating known brown dwarfs announced by a team of astronomers led by Megan E. Tannock in March 2021. With a rotational velocity of about 80 km/s (50 mi/s), it is approaching the predicted rotational speed limit beyond which it would break apart due to centripetal forces. As a consequence of its rapid rotation, the brown dwarf is slightly flattened at its poles to a similar degree as Saturn, the most oblate planet in the Solar System.[5] Its rapid rotation may enable strong auroral radio emissions via particle interactions in its magnetic field, as observed in other known rapidly-rotating brown dwarfs.[2]
Discovery
2MASS J1219+3128 was first catalogued as a point source in June 2003 by the Two Micron All-Sky Survey (2MASS) organized by the University of Massachusetts Amherst and the Infrared Processing and Analysis Center under the California Institute of Technology.[6] It was discovered to be a brown dwarf of the spectral class L8 by K. Chiu and collaborators, based on near-infrared observations obtained from the Sloan Digital Sky Survey (SDSS) at Apache Point Observatory in New Mexico, United States. Their discovery and classification of 71 L and T dwarfs including 2MASS J1219+3128 (designated alternatively as SDSS J121951.45+312849.4) was published in The Astronomical Journal in June 2006.[7]
Distance
The distance of 2MASS J1219+3128 from Earth has not yet been measured with trigonometric parallax, so instead it is calculated from the spectrophotometric relation of spectral type and near-infrared absolute magnitude.[4] Schmidt et al. (2010) estimate a spectrophotometric distance of 18.1 ± 3.7 parsecs (59 ± 12 ly) from combined SDSS iz-band and 2MASS JHK-band photometry[3] whereas Buenzli et al. (2014) estimate a spectrophotometric distance of 20.3 ± 3.0 parsecs (66.2 ± 9.8 ly) from 2MASS H-band photometry.[4]
Proper motion
2MASS J1219+3128 has a net proper motion of 238.2 mas/yr with position angle 257.98 degrees,[lower-alpha 1][lower-alpha 2] indicating motion in south-west direction on the sky.[3]
See also
The other two discoveries of rapidly-rotating brown dwarfs, presented in Tannock et al. (2021):[2]
- 2MASS J04070752+1546457 – L3.5 spectral class brown dwarf with a period of 1.23±0.01 h
- 2MASS J03480772−6022270 – T7 spectral class brown dwarf with a period of 1.080+0.004
−0.005 h
Notes
- ↑ The net proper motion is given by: [math]\displaystyle{ \mu = \sqrt{ {\mu_\delta}^2 + {\mu_\alpha}^2 \cdot \cos^2 \delta } \approx 238.2 }[/math] mas/yr, where [math]\displaystyle{ \mu_\alpha }[/math] and [math]\displaystyle{ \mu_\delta }[/math] are the components of proper motion in the RA and Dec, respectively.
- ↑ The position angle of proper motion is given by [math]\displaystyle{ \tan^{-1} \left (\frac{\mu_{\delta}}{\mu_{\alpha}} \right ) }[/math]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "2MASS J12195156+3128497 -- Brown Dwarf (M<0.08solMass)". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=2MASS+J12195156%2B3128497.
- ↑ 2.0 2.1 2.2 2.3 2.4 Tannock, Megan E.Expression error: Unrecognized word "etal". (March 2021). "Weather on Other Worlds. V. The Three Most Rapidly Rotating Ultra-cool Dwarfs". The Astronomical Journal 161 (5): 224. doi:10.3847/1538-3881/abeb67. Bibcode: 2021AJ....161..224T.
- ↑ 3.0 3.1 3.2 3.3 Schmidt, Sarah J.; West, Andrew A.; Hawley, Suzanne L.; Pineda, J. Sebastian (May 2010). "Colors and Kinematics of L Dwarfs from the Sloan Digital Sky Survey". The Astronomical Journal 139 (5): 1808–1821. doi:10.1088/0004-6256/139/5/1808. Bibcode: 2010AJ....139.1808S.
- ↑ 4.0 4.1 4.2 Buenzli, Esther; Apai, Dániel; Radigan, Jacqueline; Reid, I. Neill; Flateau, Davin (February 2014). "Brown Dwarf Photospheres are Patchy: A Hubble Space Telescope Near-infrared Spectroscopic Survey Finds Frequent Low-level Variability". The Astronomical Journal 782 (2): 18. doi:10.1088/0004-637X/782/2/77. 77. Bibcode: 2014ApJ...782...77B.
- ↑ Cofield, Calla (7 April 2021). "Trio of Fast-Spinning Brown Dwarfs May Reveal a Rotational Speed Limit". Jet Propulsion Laboratory (NASA). https://www.jpl.nasa.gov/news/trio-of-fast-spinning-brown-dwarfs-may-reveal-a-rotational-speed-limit.
- ↑ Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E. et al. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues 2246: II/246. Bibcode: 2003yCat.2246....0C. http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=II/246.
- ↑ Chiu, K.; Fan, X.; Leggett, S. K.; Golimowski, D. A.; Zheng, W.; Schneider, D. P.; Brinkmann, J. (June 2006). "Seventy-One New L and T Dwarfs from the Sloan Digital Sky Survey". The Astronomical Journal 131 (5): 2722–2736. doi:10.1086/501431. Bibcode: 2006AJ....131.2722C. https://www.stsci.edu/~golim/papers/chiu2006.pdf.
External links
- Trio of Fast-Spinning Brown Dwarfs May Reveal a Rotational Speed Limit, Calla Cofield, Jet Propulsion Laboratory, 7 April 2021
- Western space scientists identify fastest-spinning "failed stars" ever found, Jeff Renaud, University of Western Ontario, 7 April 2021
- Caught Speeding: Clocking the Fastest-Spinning Brown Dwarfs, NOIRLab, 7 April 2021
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