WISE 1541−2250

WISE 1541−2250 (full designation WISEPA J154151.66−225025.2) is a brown dwarf of spectral class Y0.5, located in the constellation Libra at approximately 18.6 light-years from Earth. A brown dwarf is like a star, but it is not big enough to start burning energy like our Sun does. Instead, it glows because of the heat left over from when it formed.

This object got a lot of attention when it was discovered in 2011. At first, people thought it was only about 9 light-years away, which would have made it the closest brown dwarf known. While that distance was later found to be a bit farther, it is still very close to us in space terms.

Brown dwarfs like WISE 1541−2250 are interesting because they are different from stars and planets. They can help scientists learn more about how stars form and what happens when objects aren’t big enough to become true stars. Other close brown dwarfs include Luhman 16, WISE 1506+7027, Epsilon Indi Ba, Bb, and UGPS 0722-05.

History of observations

WISE 1541−2250 was discovered in 2011 using data from the Wide-field Infrared Survey Explorer (WISE). WISE collected infrared images from December 2009 to February 2011. Two groups of scientists published papers about this discovery almost at the same time.

One group, led by Kirkpatrick, reported finding 98 brown dwarf systems, including WISE 1541−2250. Another group, led by Cushing, reported finding seven brown dwarfs, including WISE 1541−2250 and the first members of the Y-type spectral class, which are very cool and faint stars.

Distance

WISE 1541−2250 is a brown dwarf star located about 18.6 light-years from Earth. Scientists measured its distance using a method called trigonometric parallax.

When WISE 1541−2250 was first found in 2011, they thought it might be much closer — about 9 light-years away. This would have made it the nearest known brown dwarf. But later, more precise measurements showed it is actually farther away.

Space motion

WISE 1541−2250 moves across the sky at a speed of about 899 milliarcseconds each year. This measurement, called proper motion, helps astronomers understand how objects in space are moving relative to Earth.

Physical properties

WISE 1541−2250 is one of the coldest known brown dwarfs. It belongs to the Y-class, which are the coolest types of stars. This brown dwarf has a temperature of about 381 K, which is roughly 108 °C or 226 °F.

Scientists think there might be water clouds in its atmosphere, but they are still learning more about its composition. Studies using the JWST have found more carbon monoxide and carbon dioxide than expected. The atmosphere seems to have thick clouds, possibly made of different chemicals, but it’s still a mystery how exactly these clouds form.