WISE J064723.23−623235.5 (abbreviated WISE 0647−6232) is a nearby brown dwarf of spectral type , located in constellation Pictor at approximately 32.5 light-years from Earth. It is one of the two or three reddest and one of the four latest-type brown dwarfs known.
History of observations
Discovery WISE 0647−6232 was discovered by Kirkpatrick 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. The discovery was announced in 2013. WISE 0647−6232 was first imaged by WISE on 9 May 2010. On 17 June 2010 after preliminary data processing it was uncovered as a very cold brown dwarf candidate.
Then were carried out follow-up observations: using the Infrared Array Camera (IRAC) on Spitzer Space Telescope, starting from MJD 55458.43 (possibly 16 September 2010); J- and H-band images using Persson's Auxiliary Nasmyth Infrared Camera (PANIC) at the 6.5-meter Magellan Baade telescope at the Las Campanas Observatory, Chile, on 25 November 2010; with the FourStar infrared camera also at Magellan Baade telescope on 15 January 2013 and 23 March 2013; with the Folded-port InfraRed Echellette (FIRE) spectrograph also at Magellan Baade telescope on 24 March 2013; using the Wide Field Camera 3 (WFC3) on Hubble Space Telescope on 13–14 May 2013, and pre-image was obtained on 11 February 2013.
On 25 August 2013 Kirkpatrick et al. submitted the discovery paper to The Astrophysical Journal. WISE 0647−6232 became the 17th Y-type dwarf discovered and confirmed spectroscopically (in addition, WD 0806-661B is also almost certainly a Y-type dwarf, which was found before discovery of WISE 0647−6232, but it still lacks a spectroscopical confirmation).
Distance Currently the most accurate distance estimate of WISE 0647−6232 is a trigonometric parallax, published in 2019 by Kirkpatrick et al.: pc, or ly.
+ WISE 0647-6232 distance estimates Source Parallax, mas Distance, pc Distance, ly Ref. Kirkpatrick et al. (2013) 115 8.7 28.4 Kirkpatrick et al. (2019) 100.3 10.0 32.5
The most reliable estimate is marked in bold.
Properties WISE 0647−6232 has effective temperature 350–400 K and mass ~, but its kinematics suggests that it may belong to Columba moving group (probability of this is 92.9%, and corresponding radial velocity should be ~22 km/s), if it is so, it may be very young (~30 Myr) and have even lower mass (<). Its blue J − H color may suggest that its surface gravity may be relatively low (log(g)=3.0–3.5, where g is in units of cm·s−2). For ages from 0.1 to more than 10 Gyr log(g)=4.0–5.0. One team found a 93.2% probability of this object belonging to a group called OCEMG, which would result in a mass of .
The only redder than WISE 0647−6232 confirmed Y dwarf is WISE 1828+2650. WD 0806-661B may also be redder than WISE 0647−6232.
The other three latest-type Y dwarfs are: WISE 0350−5658 (Y1), WISE 0535−7500 (≥Y1) and WISE 1828+2650 (≥Y2).
See also List of star systems within 30–35 light-years List of Y-dwarfs
References