WISE 0647−6232

WISE J064723.23−623235.5 (abbreviated WISE 0647−6232) is a nearby brown dwarf of spectral type Y1 ± 0.5, located in constellation Pictor at approximately 32.5 light-years from Earth.^[3] It is one of the two or three reddest and one of the four latest-type brown dwarfs known.^[1]

WISE J064723.23−623235.5

WISE 0647-6232 Credit: unWISE
Observation data Epoch J2000[1]      Equinox J2000[1]
Constellation	Pictor
Right ascension	06h 47m 23.2270s[1]
Declination	−62° 32′ 39.744″[1]
Characteristics
Spectral type	Y1 ± 0.5[1]
Apparent magnitude (J (LCO filter system))	>23.0 ± 0.1[1]
Apparent magnitude (J (MKO filter system))	22.65 ± 0.27[1]
Apparent magnitude (H (LCO filter system))	>21.7 ± 0.3[1]
Apparent magnitude (H (MKO filter system))	23.40 ± 0.29[1]
Apparent magnitude (W1)	>19.09[1]
Apparent magnitude (W2)	15.32 ± 0.08[1]
Apparent magnitude (W3)	>13.49[1]
Apparent magnitude (W4)	>9.66[1]
Astrometry
Proper motion (μ)	RA: 1.19 ±1.18 mas/yr[2] Dec.: 393.81 ±0.78 mas/yr[2]
Parallax (π)	110.06±2.25 mas[2]
Distance	29.6 ± 0.6 ly (9.1 ± 0.2 pc)
Details
Mass	5–30[1] MJup
Surface gravity (log g)	3.0–5.0[1] cgs
Temperature	350–400[1] K
Other designations
WISE J064723.23-623235.5[1] WISE 0647-6232[1]
Database references
SIMBAD	data

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).^[1]

Distance

Currently the most accurate distance estimate of WISE 0647−6232 is a trigonometric parallax, published in 2019 by Kirkpatrick et al.: 10.0+0.2
−0.2 pc, or 32.5+0.8
−0.8 ly.^[3]

WISE 0647-6232 distance estimates

Source	Parallax, mas	Distance, pc	Distance, ly	Ref.
Kirkpatrick et al. (2013)	115 ± 12	8.7+1.0 −0.8	28.4+3.3 −2.7	[1]
Kirkpatrick et al. (2019)	100.3 ± 2.4	10.0+0.2 −0.2	32.5+0.8 −0.8	[3]

The best estimate is marked in bold.

Properties

WISE 0647−6232 has effective temperature 350–400 K and mass ~5–30 M_Jup, 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 (<2 M_Jup). 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.^[1]

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)^[4] and WISE 1828+2650 (≥Y2).^[1]

See also

• List of star systems within 30–35 light-years
• List of Y-dwarfs