WISE 1534–1043 (or WISEA J153429.75-104303.3, and referred to as "The Accident") is a

brown dwarf Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big en ...

(substellar object), Class Y, the coolest class, visible only in the infrared. It was accidentally discovered via the

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

. The brown dwarf is 50 light years from Earth, with a transverse velocity of over 200 km/s – over 25% faster than the next fastest stellar object of its kind. Its relative color components are unique among brown dwarfs observed to date. The best guess as to its origins are that it is a very old and low-metallicity object. On the 245th meeting of the AAS it was announced that JWST confirmed the object as a brown dwarf.

Discovery

WISE 1534-1043 was first noticed by Dan Caselden, a security engineer and citizen scientist of the

Backyard Worlds Backyard Worlds: Planet 9 is a NASA-funded citizen science project which is part of the Zooniverse (citizen science project), Zooniverse web portal. It aims to discover new brown dwarfs, faint objects that are less massive than stars, some of whi ...

Zooniverse Zooniverse is a citizen science web portal owned and operated by the Citizen Science Alliance. It is home to some of the Internet's largest, most popular and most successful Citizen science, citizen science projects. The organization grew from ...

project. He built his own online program to find brown dwarfs and found this source by accident, while looking at another source. It was first announced as a brown dwarf by the CatWISE team, who used

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

for follow-up observations. It had the highest proper motion in this sample and was undetected in Palomar/WIRC. This already hinted at the

subdwarf A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system. They are defined as stars with luminosity 1.5 to 2 magnitudes lower than that of main-sequence stars of the same ...

nature of this object. Subsequent observations with the Hubble Space Telescope WFC3 and Keck MOSFIRE uncovered the faintness of the source in the J-band. By combining Spitzer and Hubble data, a robust

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

was measured, establishing it as a possible subdwarf of type Y.

Properties

The parallax measurement for WISE 1534–1043 showed a distance of 16 parsec, resulting in a faint

absolute Absolute may refer to: Companies * Absolute Entertainment, a video game publisher * Absolute Radio, (formerly Virgin Radio), independent national radio station in the UK * Absolute Software Corporation, specializes in security and data risk ma ...

ch2 magnitude and therefore a low temperature. New spectroscopic models for metal-poor brown dwarfs, resulted in a temperature lower than 500 K (<227

°C The degree Celsius is the unit of temperature on the Celsius temperature scale "Celsius temperature scale, also called centigrade temperature scale, scale based on 0 ° for the melting point of water and 100 ° for the boiling point ...

), making WISE 1534–1043 a Y-dwarf. The moderate red Spitzer ch1-ch2 color in WISE 1534–1043 is likely caused by

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

in the atmosphere. Methane absorbs around the

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

of 3.6 μm, corresponding to the W1 (WISE) and ch1 (Spitzer) bands, causing a red color for T and Y-dwarfs. Other late T- and Y-dwarfs show a much redder ch1-ch2 color when compared to WISE 1534–1043. The low amount of

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

in WISE 1534–1043 causes the atmosphere to contain less methane and explains the moderate red ch1-ch2 color. The red J-W2 color is caused by a faint J-band magnitude. A likely cause for the faint J-band in metal-poor T/Y-dwarfs is collision-induced absorption of

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

molecules, which is enhanced in metal-poor brown dwarfs and broadly absorbs in the

near-infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those of ...

. Additional evidence hint to a peculiar Y/J-band spectrum for WISE 1534–1043. The metal-poor scenario fits with the high tangential velocity of about 200 km/s. Metal-poor objects belong to older stellar population, which are in a different orbit around the

galactic center The Galactic Center is the barycenter of the Milky Way and a corresponding point on the rotational axis of the galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a ...

compared to the

sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

. WISE 1534–1043 has such a high velocity that it is suggested to be a halo member. A pre-print paper from January 2023 describes the first J-band magnitude measurement of WISE 1534–1043, taken with Flamingos-2 at

Gemini South The Gemini Observatory comprises two 8.1-metre (26.6 ft) telescopes, Gemini North and Gemini South, situated in Hawaii and Chile, respectively. These twin telescopes offer extensive coverage of the northern and southern skies and rank among ...

. The previous J-band magnitude was estimated from a Hubble F110W measurement. Based on the model tracks and associated iso-temperature the most consistent temperature is between about 400 K and 550 K, while the most consistent metallicity is

/H lesssim-0.5dex

. The metallicity could be significantly lower and especially the extreme red J-W2 color suggests it could be cold even for a Y-dwarf. The researchers are not able to determine the Y-dwarf status of WISE 1534–1043 with absolute certainty, due to the T/Y-dwarf transition occurring at about 485 K. The researchers suggest that JWST spectroscopy is needed to determine the detailed physical properties of this object. JWST observations were approved for cylcle 2 with

NIRSpec The NIRSpec (Near-Infrared Spectrograph) is one of the four scientific instruments flown on the James Webb Space Telescope (JWST). The JWST is the follow-on mission to the Hubble Space Telescope (HST) and is developed to receive more information ...

and

MIRI Miri () is a coastal city in north-eastern Sarawak, Malaysia, located near the border of Brunei, on the island of Borneo. The city covers an area of , located northeast of Kuching and southwest of Kota Kinabalu. Miri is the second largest ...

. In the spectrum of WISE 1534–1043 researchers made the first detection of

silane Silane (Silicane) is an inorganic compound with chemical formula . It is a colorless, pyrophoric gas with a sharp, repulsive, pungent smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental ...

(SiH₄) in the atmosphere of a

substellar object A substellar object, sometimes called a substar, is an astronomical object, the mass of which is smaller than the smallest mass at which hydrogen fusion can be sustained (approximately 0.08 solar masses). This definition includes brown dwarfs and f ...

. The publication concerning this discovery is in review. WISE 1534–1043 has the bluest F110W-J color available for late T and Y-dwarfs.

Disproven alternative explanations

Previous alternative explanations included an extremely low-mass and young brown dwarf. This scenario cannot explain the high velocity, as young objects usually show a low tangential velocity. Another alternative was an ejected

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

. Even for a young and recently ejected exoplanet, models predicted a mass of about 0.3 .

Microlensing Gravitational microlensing is an astronomical phenomenon caused by the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronome ...

surveys have shown that ejected exoplanets with such high masses are extremely rare and it is unlikely to find any in the neighbourhood of the Sun. An ultra-cold stellar remnant cannot fully explain the colors of WISE 1534–1043. It would also require a

white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

that is older than the Milky Way or an exotic scenario in which the white dwarf got stripped to its bare core by a source and then ripped from its ablating source. Finding such a source near the Sun is highly improbable. All these explanations were disproven after JWST observations in 2025, which confirmed it as a metal-poor brown dwarf.

Notes

Reference

External links