W1055+5443 is a Y-type brown dwarf, observations find

Utilizing the Keck II telescope, astronomers have carried out near-infrared spectroscopic observations of a close-by brown dwarf often known as CWISE J105512.11+544328.3, or W1055+5443 for brief. Outcomes of the observational marketing campaign, offered October 14 on the pre-print server arXiv, reveal that this object belongs to the uncommon class of ultracool brown dwarfs, dubbed Y dwarfs.

Brown dwarfs are intermediate substellar objects between planets and stars with plenty beneath the hydrogen burning restrict—about 80 Jupiter plenty. One uncommon subclass of brown dwarfs, with efficient temperatures decrease than 500 Okay, is named Y dwarfs. They’re the best and least luminous substellar objects up to now detected.

W1055+5443 is a brown dwarf at a distance of some 22.5 light years, found in 2012 and initially categorised as a T dwarf (a subclass of brown dwarfs with efficient temperatures between 500 and 1,500 Okay). Nevertheless, new observations made by a crew of astronomers led by Grady Robbins of the College of Florida, counsel that the thing needs to be reclassified as a Y dwarf. The discovering relies on the info collected with the Close to-Infrared Echellette Spectrometer (NIRES) on the Keck II telescope.

“Close to-infrared spectral evaluation is up to now the best technique for classifying late T and early Y dwarfs, as they’re very faint within the optical,” the researchers defined.

The observations discovered that W1055+5443 has an efficient temperature of about 500 Okay and an absolute magnitude of 15.18 magazine. These outcomes point out that W1055+5443 is most definitely an early Y dwarf reasonably than a late T dwarf.

Furthermore, the crew discovered that the spectrum of W1055+5443 exhibits robust ammonia absorption plus methane and water absorption within the H-band, what additional helps the Y-type classification. The astronomers added that the brown dwarf showcases an anomalously excessive H-band peak amplitude.

The research additionally discovered that the Okay-band flux of W1055+5443 is surprisingly excessive. In line with the authors of the paper, the Okay-band spectrum of this object seems higher matched to that of a mid-late T dwarf reasonably than a Y dwarf, but it’s nonetheless not an ideal match. The tangential velocity of W1055+5443 was estimated to be at a stage of fifty km/s—due to this fact comparatively excessive when in comparison with the solar neighborhood median worth for brown dwarfs.

The astronomers famous that the bizarre properties of W1055+5443 could also be defined by a beforehand undetected companion object. Nevertheless, based mostly on the accessible knowledge and binary modeling carried out by them, they excluded this risk.

Summing up the outcomes, the scientists concluded that W1055+5443 is of spectral kind Y0. They suggest additional observations of this brown dwarf as a lot of its properties like age or mass are nonetheless undetermined.

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