WISE 1828+2650 (full designation WISEPA J182831.08+265037.8) is a possibly binary brown dwarf or rogue planet of spectral class >Y2, located in constellation Lyra at approximately 32.5 light-years from Earth. It is the "archetypal member" of the Y spectral class.
History of observations
Discovery
WISE 1828+2650 was discovered in 2011 from data collected by NASA's 40 cm (16 in) Wide-field Infrared Survey Explorer (WISE) space telescope at infrared wavelength. WISE 1828+2650 has two discovery papers: Kirkpatrick et al. (2011) and Cushing et al. (2011), however, basically with the same authors and published nearly simultaneously.
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 1828+2650 – coolest of them. 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. These seven objects are also the faintest seven of 98 brown dwarfs, presented in Kirkpatrick et al. (2011).
Distance
Currently the most accurate distance estimate of WISE 1828+2650 is a trigonometric parallax, published in 2021 by Kirkpatrick et al.: , corresponding to a distance of , or .
Proper motion
WISE 1828+2650 has a proper motion of milliarcseconds per year.
Physical properties
Until the discovery of WISE 0855−0714 in 2014 WISE 1828+2650 was considered as the coldest currently known brown dwarf or the first example of free-floating planet (it is not currently known if it is a brown dwarf or a free-floating planet). It has a temperature in the range and was initially estimated below 300 K, or about . It has been assigned the latest known spectral class (>Y2, initially estimated as >Y0).
The mass of WISE 1828+2650 is in the range for ages of 0.1–10 Gyr.
High tangential velocity of WISE 1828+2650, characteristic of an old disk population, indicates possible age of WISE 1828+2650 in the range 2–4 Gyr, leading to mass estimate of about .
WISE 1828+2650 is similar in appearance to the other Y-type object WD 0806-661 B. WD 0806-661 B could have formed as a planet close to its primary, WD 0806-661 A, and later, when the primary became a white dwarf and lost most of its mass, have migrated into a larger orbit of 2500 AU, and similarity between WD 0806-661 B and WISE 1828+2650 may indicate that WISE 1828+2650 had formed in the same way.
Possible binarity
Comparison between WISE 1828+2650 and WD 0806-661 B may suggest that WISE 1828+2650 is a system of two equal-mass objects. Observations with Hubble Space Telescope (HST) and Keck-II LGS-AO system had not revealed binarity, suggesting that if any such companion exists, it would have an orbit less than 0.5 AU, and no direct evidence for binarity yet exists. However, the spectrum of the system best fits a pair of brown dwarfs, each with an effective temperature of about 325 K and a mass of about .
JWST NIRCam imaging observations did not find a companion at a separation larger than 0.5 astronomical units. NIRSpec low resolution prism observations cannot be explained with existing Sonora Bobcat models of planetary objects, neither single nor multiple. The binary model fails to provide an improved fit for the existing photometric data.
Comparison
See also
The other six discoveries of brown dwarfs, published by Cushing et al. in 2011: WISE 0148−7202 (T9.5) WISE 0410+1502 (Y0) WISE 1405+5534 (Y0 (pec?)) WISE 1541−2250 (Y0.5) WISE 1738+2732 (Y0) WISE 2056+1459 (Y0)
Notes
References
External links
NASA news release
Science news
Solstation.com (New Objects within 20 light-years)