WISE 1639−6847
Brown dwarf in the constellation Triangulum Australe
From Wikipedia, the free encyclopedia
WISE J163940.83−684738.6 (designation is abbreviated to WISE 1639−6847[5], or W1639[4]) is a brown dwarf of spectral class Y0 pec,[2] located in the constellation Triangulum Australe at 15.5 light-years from Earth.[1] It is the closest star or brown dwarf in its constellation,[6]: 84 and the second closest known Y dwarf as of February 2024.[7]
WISE 1639-6847 in near-infrared with Hubble. It shows the brown dwarf moving within 1 ½ years Credit: Hubble Space Telescope; Fontanive et al. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Triangulum Australe |
| Right ascension | 16h 39m 39.730s[1] |
| Declination | −68° 47′ 06.69″[1] |
| Characteristics | |
| Spectral type | Y0 pec[2] |
| Astrometry | |
| Proper motion (μ) | RA: 576.94±0.22 mas/yr[1] Dec.: −3108.48±0.21 mas/yr[1] |
| Parallax (π) | 211.11±0.56 mas[1] |
| Distance | 15.45 ± 0.04 ly (4.74 ± 0.01 pc) |
| Other designations | |
| GJ 12393[3],WISEPC J163940.83-684738.6[4] WISE 1639-6847[5] W1639[4] | |
| Database references | |
| SIMBAD | data |
  WISE 1639−6847 Location of WISE 1639−6847 in the constellation Triangulum Australe | |
Discovery
WISE 1639−6847 was discovered in 2012 by C. G. Tinney et al. from data, collected by Wide-field Infrared Survey Explorer (WISE) Earth-orbiting satellite—NASA infrared-wavelength 40 cm (16 in) space telescope, which mission lasted from December 2009 to February 2011.
In 2012 Tinney et al. carried out follow-up observations of WISE 1639−6847 using the FourStar infrared mosaic camera mounted on the 6.5 m Magellan Baade telescope at Las Campanas Observatory, Chile (on 2012 May 10–11 (UT)); and spectroscopy using the Folded-port Infrared Echellette (FIRE) also mounted on the 6.5 m Magellan Baade telescope (on 2012 July 10 (UT)).
In 2012 Tinney et al. published a paper in The Astrophysical Journal, where they presented discovery of a newfound by WISE Y-type brown dwarf WISE 1639−6847 (the only brown dwarf discovery, presented in the article): the paper was accepted for publication on 20 September 2012, submitted to arXiv on 27 September 2012, and published in November 2012.[4]
Physical properties
WISE 1639−6847 has absolute magnitude in J-band 22.14 ± 0.22.[4] WISE 1639−6847 was first classified to have a spectral type between Y0 and Y0.5. Observations with Hubble WFC3 near-infrared grism spectroscopy showed that the J-band peak matched with the Y0 standard. The Y-band peak and the Y-J color showed that it was unusual compared to other Y-dwarfs and therefore a spectral type of Y0 pec was applied. The pec stands for peculiar or unusual.[2] Modelling of this Y-dwarf struggles to reproduce the spectrum. Only with rather unrealistic high temperature and low gravity it was possible to reproduce the spectrum.[8]