WISE 1541-2250

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Coordinates: Sky map 15h 41m 51.57s, −22° 50′ 25.03″

WISEPA J154151.66-225025.2
Observation data
Epoch MJD 55424.68[1]      Equinox J2000[1]
Constellation Libra
Right ascension 15h 41m 51.57s[1]
Declination –22° 50′ 25.03″[1]
Spectral type Y0.5[2]
Apparent magnitude (J (MKO filter system)) 21.16 ± 0.36[1]
Apparent magnitude (H (MKO filter system)) 20.99 ± 0.52[1]
Proper motion (μ) RA: -0.857 ± 0.012[3] mas/yr
Dec.: -0.087 ± 0.013[3] mas/yr
Parallax (π) 176 ± 9[3] mas
Distance 18.5 ± 0.9 ly
(5.7 ± 0.3 pc)
Mass 12 (8–12)[4] MJup
Radius 1.01 (1.01–1.07)[4] RJup
Surface gravity (log g) 4.50 (4.25–4.5)[4] cgs
Temperature 350[4] K
Other designations
WISEPA J154151.66-225025.2[1]
WISEP J1541-2250[4]
WISE J1541-2250[1]
WISE 1541-2250[1]
Artist's vision of a Y-dwarf

WISEPA J154151.66-225025.2 (designation is abbreviated to WISE 1541-2250) is a sub-brown or brown dwarf of spectral class Y0.5,[2] located in constellation Libra at approximately 18.5 light-years from Earth.[3] This object received popular attention when its discovery was announced in 2011 at a distance estimated to be only about 9 light-years, which would have made it the closest brown dwarf known.[5] (For really close brown dwarfs see, for example, Luhman 16, WISE 1506+7027, Epsilon Indi Ba, Bb, or UGPS 0722-05). It is not the farthest known Y-type brown dwarf to Earth.

History of observations[edit]


WISE 1541-2250 was discovered in 2011 from data collected by the Wide-field Infrared Survey Explorer (WISE), an infrared-wavelength space telescope of 40 cm (16 in) aperture, whose mission lasted from December 2009 to February 2011. WISE 1541-2250 has two discovery papers: Kirkpatrick et al. (2011) and Cushing et al. (2011) with mostly the same authors and published nearly simultaneously.[1][4]

  • Kirkpatrick et al. presented the discovery of 98 brown dwarf systems with components of spectral types M, L, T and Y, among which was WISE 1541-2250.[1][~ 1]
  • Cushing et al. presented the discovery of seven brown dwarfs, one of the T9.5 type and six of the Y-type, the first members of the Y spectral class discovered and spectroscopically confirmed, including an "archetypal member" of the Y spectral class, WISE 1828+2650, and WISE 1541-2250.[4] 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 1541-2250 is a trigonometric parallax, published in 2014 by Beichman et al.: 0.176 ± 0.009 arcsec, corresponding to a distance 5.68+0.31
pc, or 18.5+1.0

For several months after its discovery, before publication of parallax by Kirkpatrick et al. in 2012,[2] WISE 1541-2250 was considered to be the nearest known brown dwarf at approximately 9 light-years from the Sun, and the seventh-nearest of all star systems, at slightly more than twice the distance of the nearest known star system Alpha Centauri. This view existed because of very rough preliminary parallax with baseline 1.2 years, published in the discovery paper: 0.351 ± 0.108 arcsec, corresponding to a distance 2.8+1.3
pc, or 9.3+4.1
ly.[1] Also, there were other estimates: spectrophotometric distance estimate 8.2 pc (26.7 ly),[1] and photometric distance estimate 1.8+0.2
pc (5.9+0.6

WISE 1541-2250 distance estimates

Source Parallax, mas Distance, pc Distance, ly Ref.
Kirkpatrick et al. (2011), Table 6 8.2 26.7 [1]
Kirkpatrick et al. (2011), Table 7 351 ± 108 2.8+1.3
Cushing et al. (2011), Table 7 1.8+0.2
Kirkpatrick et al. (2012), Tables 4 & 8 ~ 238 ~ 4.2 ~ 13.7 [2]
Marsh et al. (2013)
(according Kirkpatrick et al. (2012))
87 ± 54 11.5+18.8
Marsh et al. (2013) −21 ± 94 >6.0[~ 2] >19.6 [6]
Dupuy & Kraus (2013) 74 ± 31[~ 3] 13.5+9.7
Beichman et al. (2014) 176 ± 9 5.68+0.31

Non-trigonometric distance estimates are marked in italic. The best estimate is marked in bold.

Space motion[edit]

WISE 1541-2250 has proper motion of about 861 milliarcseconds per year.[3]

WISE 1541-2250 proper motion estimates

Source μ,
P. A.,
Kirkpatrick et al. (2011) 810 254 −780 ± 234 −218 ± 249 [1]
Marsh et al. (2013) 1021 254 −983 ± 111 −276 ± 116 [6]
Dupuy & Kraus (2013) 870 ± 130 269 ± 4 −870 ± 130 −13 ± 58 [7]
Beichman et al. (2014) 861 264 -857 ± 12 -87 ± 13 [3]

The most accurate estimates are marked in bold.

Spectral class and temperature[edit]

WISE 1541-2250 is among the first known examples of a Y-class brown dwarf, the coldest spectral class of stars, and has temperature about 350 K[4] (about 77 °C / 170 °F). Its spectral class is Y0.5[2] (initially was estimated as Y0).[1][4]

See also[edit]

The other six discoveries of brown dwarfs, published in Cushing et al. (2011):[4]



  1. ^ These 98 brown-dwarf systems are among the first brown-dwarf systems discovered in data collected by WISE and 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.
  2. ^ In this parallax and distance estimates the most probable distance value does not equal to inverse maximum likelihood parallax value, as would be in the case of exact parallax and distance values. This is due to the fact that Marsh et al. used a more sophisticated method of converting maximum likelihood parallaxes into most probable distances, that uses also some prior information, and not just the calculation of the inverse value. (The method description see in Marsh et al. (2013), Section 4).
  3. ^ Relative parallax.


  1. ^ a b c d e f g h i j k l m n o p q r Kirkpatrick, J. Davy; Cushing, Michael C.; Gelino, Christopher R.; Griffith, Roger L.; Skrutskie, Michael F.; Marsh, Kenneth A.; Wright, Edward L.; Mainzer, A.; Eisenhardt, Peter R.; McLean, Ian S.; Thompson, Maggie A.; Bauer, James M.; Benford, Dominic J.; Bridge, Carrie R.; Lake, Sean E.; Petty, Sara M.; Stanford, S. A.; Tsai, Chao-Wei; Bailey, Vanessa; Beichman, Charles A.; Bloom, Joshua S.; Bochanski, John J.; Burgasser, Adam J.; Capak, Peter L.; Cruz, Kelle L.; Hinz, Philip M.; Kartaltepe, Jeyhan S.; Knox, Russell P.; Manohar, Swarnima; Masters, Daniel; Morales-Calderon, Maria; Prato, Lisa A.; Rodigas, Timothy J.; Salvato, Mara; Schurr, Steven D.; Scoville, Nicholas Z.; Simcoe, Robert A.; Stapelfeldt, Karl R.; Stern, Daniel; Stock, Nathan D.; Vacca, William D. (2011). "The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)". The Astrophysical Journal Supplement 197 (2): 19. arXiv:1108.4677v1. Bibcode:2011ApJS..197...19K. doi:10.1088/0067-0049/197/2/19.  edit
  2. ^ a b c d e f Kirkpatrick, J. D.; Gelino, C. R.; Cushing, M. C.; Mace, G. N.; Griffith, R. L.; Skrutskie, M. F.; Marsh, K. A.; Wright, E. L.; Eisenhardt, P. R.; McLean, I. S.; Mainzer, A. K.; Burgasser, A. J.; Tinney, C. G.; Parker, S.; Salter, G. (2012). "Further Defining Spectral Type "Y" and Exploring the Low-mass End of the Field Brown Dwarf Mass Function". The Astrophysical Journal 753 (2): 156. arXiv:1205.2122. Bibcode:2012ApJ...753..156K. doi:10.1088/0004-637X/753/2/156.  edit
  3. ^ a b c d e f g h Beichman, C.; Gelino, Christopher R.; Kirkpatrick, J. Davy; Cushing, Michael C.; Dodson-Robinson, Sally; Marley, Mark S.; Morley, Caroline V.; Wright, E. L. (2014). "WISE Y Dwarfs As Probes of the Brown Dwarf-Exoplanet Connection". The Astrophysical Journal 783 (2): 68. arXiv:1401.1194v2. Bibcode:2014ApJ...783...68B. doi:10.1088/0004-637X/783/2/68.  edit
  4. ^ a b c d e f g h i j k l Cushing, Michael C.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Griffith, Roger L.; Skrutskie, Michael F.; Mainzer, A.; Marsh, Kenneth A.; Beichman, Charles A.; Burgasser, Adam J.; Prato, Lisa A.; Simcoe, Robert A.; Marley, Mark S.; Saumon, D.; Freedman, Richard S.; Eisenhardt, Peter R.; Wright, Edward L. (2011). "The Discovery of Y Dwarfs using Data from the Wide-field Infrared Survey Explorer (WISE)". arXiv:1108.4678v1 [astro-ph.SR]. Bibcode 2011ApJ...743...50C. doi:10.1088/0004-637X/743/1/50. edit
  5. ^ "NASA'S Wise Mission Discovers Coolest Class of Stars". WISE Mission News (2011-263). 2011-08-23. 
  6. ^ a b Marsh, Kenneth A.; Wright, Edward L.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Cushing, Michael C.; Griffith, Roger L.; Skrutskie, Michael F.; Eisenhardt, Peter R. (2013). "Parallaxes and Proper Motions of Ultracool Brown Dwarfs of Spectral Types Y and Late T". The Astrophysical Journal 762 (2): 119. arXiv:1211.6977. Bibcode:2013ApJ...762..119M. doi:10.1088/0004-637X/762/2/119.  edit
  7. ^ a b Dupuy, Trent J.; Kraus, Adam L. (2013). "Distances, Luminosities, and Temperatures of the Coldest Known Substellar Objects". arXiv:1309.1422v1 [astro-ph.SR]. Bibcode 2013arXiv1309.1422D.

External links[edit]