WISEPA J173835.53+273258.9

WISEPA J173835.53+273258.9 (abbreviated WISE 1738+2732) is a brown dwarf of spectral class Y0,^[1][2] located in the constellation Hercules at 24.9 light-years from Earth.^[6]

WISEPA J173835.53+273258.9

WISE 1738+2732 Credit: unWISE
Observation data Epoch MJD 55451.22[1]      Equinox J2000[1]
Constellation	Hercules
Right ascension	17h 38m 35.54s[1]
Declination	27° 32′ 58.78″[1]
Characteristics
Spectral type	Y0[1][2]
Apparent magnitude (J (MKO filter system))	19.47 ± 0.08[1]
Apparent magnitude (H (MKO filter system))	20.66 ± 0.38[1]
Astrometry
Proper motion (μ)	RA: 36.08 ±0.20 mas/yr[3] Dec.: –341.46 ±0.17 mas/yr[3]
Parallax (π)	133.65±0.83 mas[3]
Distance	24.4 ± 0.2 ly (7.48 ± 0.05 pc)
Details[4]
Mass	13+11 −7 MJup
Radius	1.14±0.03 RJup
Luminosity	3.02+0.37 −0.27×10−7 L☉
Surface gravity (log g)	4.46+0.26 −0.34 cgs
Temperature	402+12 −9 K
Rotation	6 hours
Age	1–4 Gyr
Other designations
WISEPA J173835.53+273258.9[1] WISEP J1738+2732[5] WISE J1738+2732[1] WISE 1738+2732[1]
Database references
SIMBAD	data

History of observations

WISE 1738+2732 was discovered in 2011 from data, collected by the 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. WISE 1738+2732 has two discovery papers: Kirkpatrick et al. (2011) and Cushing et al. (2011), however, basically with the same authors and published nearly simultaneously.^[1][5]

• Kirkpatrick et al. presented discovery of 98 new found by WISE brown dwarf systems with components of spectral types M, L, T and Y, among which also was WISE 1738+2732.^{[1][~ 1]}
• Cushing et al. presented discovery of seven brown dwarfs — one of T9.5 type, and six of Y-type — first members of the Y spectral class, ever discovered and spectroscopically confirmed, including "archetypal member" of the Y spectral class WISE 1828+2650, and WISE 1738+2732.^[5] These seven objects are also the faintest seven of 98 brown dwarfs, presented in Kirkpatrick et al. (2011).^[1]

Currently the most accurate distance estimate of WISE 1738+2732 is a trigonometric parallax, published in 2021 by Kirkpatrick et al.: 130.9±2.1 mas, corresponding to a distance of 7.6±0.1 pc, or 24.9±0.4 ly.^[6] WISE 1738+2732 has a proper motion of 481.2±1.1 milliarcseconds per year.^[6]

Properties

The object's temperature estimate is 350 (350–400) K.^[5] Its spectrum is similar with spectrum of another Y-dwarf WISE 1405+5534.

Disequilibrium chemistry models suggest that this Y-dwarf has a low mass of about 3-9 M_Jup, making it a possible isolated planetary-mass object, together with WISE 0350-5658.^[7] A more recent paper finds a mass of 5-14 M_Jup.^[8]

WISE 1405 is variable in the near- and mid-infrared. The observations were made with the Gemini Observatory and Spitzer. It has a rotation period of 6.0±0.1 hours and the amplitude is 3% for 4.5 μm and may be as high as 5-30% in the near-infrared. This dependence on wavelength can be reproduced with patchy cloud layers made up of potassium chloride (KCl) and sodium sulfide (Na₂S).^[9]

See also

• List of star systems within 20–25 light-years
• List of Y-dwarfs
• WISE 0148-7202 (T9.5)
• WISE 0410+1502 (Y0)
• WISE 1405+5534 (Y0 (pec?))
• WISE 1541-2250 (Y0.5)
• WISE 1828+2650 (≥Y2)
• WISE 2056+1459 (Y0)

Notes

1. These 98 brown dwarf systems are only among first, not all brown dwarf systems, discovered from data, collected by WISE: six discoveries were published earlier (however, also listed in Kirkpatrick et al. (2011)) in Mainzer et al. (2011) and Burgasser et al. (2011), and the other discoveries were published later.