WISE 0855-0714

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Brown dwarf
WISE J085510.83−071442.5
Time-lapse photo sequence of the movement of WISE 0855-0714 in the sky, created from images of the space telescopes WISE and Spitzer. [1]
Time-lapse photo sequence of the movement of WISE 0855-0714 in the sky, created from images from the space telescopes WISE and Spitzer.
Observation
dates equinoxJ2000.0 , epoch : J2000.0
Constellation Water snake
Right ascension 08 h 55 m 10.83 s
declination -07 ° 14 ′ 42.5 ″
parallax 433 ± 15 mas
distance 7.53 ± 0.26  ly
(2.31 ± 0.08  pc )
Typing
Spectral class Y
Physical Properties
Dimensions approx. 3 to 10 M
Effective temperature 225 to 260 K
Other names
and catalog entries
Further designations:

WISE 0855-0714

WISE 0855-0714 (full name: WISE J085510.83-071442.5 ) is a Sub-Brown Dwarf (Y dwarf or object of planetary mass ) in 2.31 ± 0.08 parsecs (7.53 ± 0.26 light years ) Distance from Earth, the discovery of which was announced in April 2014 by Kevin Luhman based on data from the Wide-field Infrared Survey Explorer (WISE).

The object has (as of 2014) the third highest proper movement (8130 ± 22 mas / a ) after Barnard's star (10300 mas / a) and Kapteyn's star (8600 mas / a). Furthermore, it has (as of: 2014) the fourth highest parallax (433 ± 15 mas) of all known stars and brown dwarfs, what it is called the fifth closest extrasolar system to the Sun, after Proxima , Alpha Centauri , Barnard's Arrow Star , Luhman 16 (also WISE 1049− 5319). It is also the coldest object of its type found in interstellar space, at a temperature between 225 and 260 K (−48 to −13 ° C , −55 to 8 ° F ).

characterization

Observations

The sun is closest stars and brown dwarfs, including WISE 0855-0714 . The year in which the distance was determined is indicated.

The WISE object was discovered in March 2013 and subsequent observations were made with the Spitzer Space Telescope and the Gemini Nord Telescope . The designation WISE J085510.83−071442.5 contains the coordinates and indicates that the object is located in the constellation Water Snake.

Distance and proper movement

Based on direct observations, WISE 0855-0714 has a large parallax. This geometric measurement method gives a distance of around 7.53 ± 0.26 light years, with a small error due to the strength of the parallax effect and the accuracy of the observations. The proper motion of WISE 0855-0714 in the sky has also been directly observed over time, which contributed to its discovery as it stood out in the observations, but the proper motion itself is a combination of its speed in the galactic neighborhood relative to the solar system and its proximity to it. If the object were to move just as fast (but further away) or slower (but closer), or faster near the sun (but at a higher angle in the direction of the sun or away from it), it would have a slower proper movement.

Determination of the distance for WISE 0855-0714

source Parallax ( mas ) Distance ( pc ) Distance ( Lj ) Distance ( Pm )
Luhman (2014) 454 ± 45 2.2 +0.24 -0.2 7.2 +0.8 -0.6 68 +7.5 −6.1
Wright et al. (2014) (e-print v1) 448 ± 32 2.23 +0.17 -0.15 7.3 +0.6 -0.5 68.9 +5.3 -4.6
Wright et al. (2014) 448 ± 33 2.23 +0.18 -0.15 7.3 +0.6 -0.5 68.9 +5.5 -4.7
Luhman & Esplin (2014) 433 ± 15 2.31 ± 0.08 7.53 +0.27 -0.25 71.3 +2.6 -2.4

Non-trigonometric distance determinations are marked in italics . The most precise determination is marked in bold .

Determination of the proper movement for WISE 0855-0714

source μ (mas / a) PA ( ° ) μ α cos (δ) (mas / a) μ δ (mas / a)
Luhman (2014) 8090 ± 96 275 ± 0.5 −8060 ± 90 700 ± 70
Wright et al. (2014) (e-print v1) 8072 ± 29 274.17 ± 0.3 −8051 ± 26 587 ± 40
Wright et al. (2014) 8078 ± 51 274.7 ± 0.4 −8051 ± 47 657 ± 50
Luhman & Esplin (2014) 8130 ± 22 274.94 ± 0.15 −8100 ± 20 700 ± 20

The most precise determinations are marked in bold . Calculated values ​​are in italics, values ​​that are specified in the sources are not in italics.

Spectrometry

The luminosity of WISE 0855-0714 in the thermal infrared, combined with its absolute brightness - as its distance is known - was used to put it in context with different models. The best characterization of its brightness was in the W2 band at 4.6 µm with an apparent brightness of 13.89 ± 0.05 mag, although it appears brighter in the lower infrared. Infrared images by the Magellan-Baade Telescope suggest the existence of water clouds.

classification

Based on the brown dwarf models, it is estimated that WISE 0855-0714 has a mass of 3 to 10 Jupiter masses . So far there is no consensus in science on the designation of such objects. As a criterion as the lower limit for brown dwarfs, a mass of 13 Jupiter masses is used, above which objects are capable of deuterium fusion . Objects of lesser mass are then generally referred to as objects of planetary mass (or simply as planets, although this does not correspond to the current definition of this term by the IAU). Since this WISE object has no gravitationally bound companion, it could therefore also be called a vagabonding planet , similar to Cha 110913-773444 , which was identified as the first such object in 2004. An alternative type of classification takes into account the formation process and designates objects that have been created by the collapse of a gas cloud and are in the range of the mass of planets as sub- brown dwarfs or planetary-mass brown dwarfs .

Its luminosity, distance, and mass combined, WISE 0855-0714 is the coldest sub-brown dwarf (or brown dwarf of planetary mass), with a modeled temperature of 225 to 260 K (-48 to -13 ° C), depending on the model .

further reading

  • Beichman, C .; Gelino, Christopher R .; Kirkpatrick, J. Davy; Cushing, Michael C .; Dodson-Robinson, Sally et al .: WISE Y Dwarfs As Probes of the Brown Dwarf-Exoplanet Connection . 2014, arxiv : 1401.1194v2 (WISE 0855-0714 is not mentioned in this publication; it refers to other objects of the spectral class Y that were discovered with WISE).

Web links

Individual evidence

  1. a b c d e f g h NASA: NASA's Spitzer and WISE Telescopes Find Close, Cold Neighbor of Sun. Retrieved March 23, 2015 .
  2. a b c d e Kevin Luhman: A New Parallax Measurement for the Coldest Known Brown Dwarf . arxiv : 1409.5899 .
  3. a b c d Kevin Luhman: Discovery of a ~ 250 K Brown Dwarf at 2 pc from the Sun . arxiv : 1404.6501 .
  4. a b c d Edward L. Wright, Amy Mainzer, J. Davy Kirkpatrick, Frank Masci, Michael C. Cushing, James Bauer, Sergio Fajardo-Acosta, Christopher R. Gelino, Charles A. Beichman, MF Skrutskie, T. Grav , Peter RM Eisenhardt, Roc Cutri: NEOWISE-R Observation of the Coolest Brown Dwarf . arxiv : 1405.7350 .
  5. Jacqueline K. Faherty, CG Tinney, Andrew Skemer, Andrew J. Monson: Indications of Water Clouds in the Coldest Known Brown Dwarf . arxiv : 1408.4671 .
  6. ^ Leonidas Papadopoulos: Between the Planet and the Star: A New Ultra-Cold, Sub-Stellar Object Discovered Close to Sun. Retrieved March 23, 2015 .