WISE 0458+6434

WISEPC J045853.90+643451.9 (designation is abbreviated to WISE 0458+6434) is a binary system of two (A and B) ultracool brown dwarfs of spectral classes T8.5 and T9.5, respectively, located in constellation Camelopardalis at approximately 47 ly from Earth.

Discovery
WISE 0458+6434 A was discovered in 2010 by A. Mainzer 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 2010 Mainzer et al. had conducted follow-up observations of WISE 0458+6434:
 * on 2010 March 17 (UT) YJH photometry with FanCam, an infrared imager operating at the University of Virginia’s Fan Mountain 31 in telescope;
 * on 2010 March 19 (UT) 1.5–2.3 μm spectroscopy with LUCIFER near-infrared camera/spectrograph at the Large Binocular Telescope (LBT);
 * on 2010 Sep 12 (UT) 0.8–2.5 μm spectroscopy with SpeX on the 3.0 m NASA Infrared Telescope Facility on Mauna Kea.

In early 2011 Mainzer et al. published a paper in The Astrophysical Journal, where they presented discovery of one new found by WISE brown dwarf — ultra-cool object WISE 0458+6434. This object became the first brown dwarf, found by WISE.

Several months later, also in 2011, Kirkpatrick et al. published a paper in The Astrophysical Journal Supplement, where they presented characteristics of 104 first discovered by WISE brown dwarf systems — 98 new found systems and six systems, presented in published earlier papers (one in Mainzer et al. (2011), and five in Burgasser et al. (2011)), among which also was WISE 0458+6434.

Discovery of the companion
WISE 0458+6434 B was discovered in 2011 by Gelino et al., when they examined for binarity nine brown dwarfs using Laser Guide Star Adaptive Optics system (LGS-AO) on Keck II telescope on Mauna Kea; seven of these nine brown dwarfs were also newfound, and two were discovered before, including WISE 0458+6434. These observations had indicated that two of these nine brown dwarfs, including WISE 0458+6434, are binary. Angular separation of WISE 0458+6434 components was 80 mas. Component B is also of late T-type — T9.5 (initially was estimated as T9).

Distance
Currently the most accurate distance estimate of WISE 0458+6434 is a trigonometric parallax, measured using Spitzer Space Telescope and published in 2013 by Trent Dupuy and Adam Kraus: 0.070 ± 0.019 arcsec, corresponding to a distance 14.3$43$ pc, or 46.6$5$ ly.

WISE 0458+6434 distance estimates

Non-trigonometric distance estimates are marked in italic. The best estimate is marked in bold.

Space motion
WISE 0458+6434 has proper motion of about 347 milliarcseconds per year.

WISE 0458+6434 proper motion estimates

The most accurate estimates are marked in bold.

Physical properties
The brown dwarfs' temperature estimates are 600 K, or 327 °C (A) and 500 K, or 227 °C (B), both cooler than Venus.

NH3 in the spectrum of component B
According proposed by Cushing et al. in 2011 T/Y transition standard, WISE J0458+6434 B does not relate to Y-type. However, its spectrum has feature similar to those in the spectra of the Y0 dwarfs WISE 1405+5534 and WISE 1738+2732, which were tentatively attributed to NH3 (ammonia) absorption — a compelling evidence for NH3 absorption.