| 词条 | WISE 0855−0714 |
| 释义 |
| name = WISE J085510.83−071442.5{{Starbox image | image = | caption = Time-lapsed photo sequence of WISE 0855−0714's movement in the sky using captured images from the WISE and the Spitzer telescopes.{{Starbox observe | epoch = J2000 | constell = Hydra | ra = {{RA|08|55|10.83}} | dec = {{DEC|-07|14|42.5}} | appmag_v = {{Starbox character | type = Sub-brown dwarf | class = Class Y2 | appmag_1_passband = J | appmag_1 = {{val|25.00|0.53}}[1]{{Starbox astrometry | radial_v = | prop_mo_ra = {{val|p=−|8118|8}}[3] | prop_mo_dec = {{val|680|7}}[3] | parallax = 449 | p_error = 8 | parallax_footnote = [3] | dist_ly = {{val|7.27|0.13}} | dist_pc = {{val|2.23|0.04}} | absmag_v = {{Starbox detail | mass_mj = ~3–10 | radius_rj = | luminosity = | luminosity_bolometric = | luminosity_visual = | gravity = | temperature = 225-260 | metal = | metal_fe = | rotation = | rotational_velocity = | age = {{Starbox catalog | names = {{nowrap|WISEA J085510.74-071442.5}}{{Starbox reference | Simbad = WISEA+J085510.74-071442.5{{Starbox end}}WISE 0855−0714 (full designation WISE J085510.83−071442.5[6]) is a sub-brown dwarf {{val|2.23|0.04|u=parsecs}} ({{val|7.27|0.13|u=light-years}})[3] from Earth, the discovery of which was announced in April 2014 by Kevin Luhman using data from the Wide-field Infrared Survey Explorer (WISE). {{As of|2014}}, WISE 0855−0714 has the third-highest proper motion ({{val|8118|8|u=mas/yr}})[3] after Barnard's Star ({{val|10300|u=mas/yr}}) and Kapteyn's Star ({{val|8600|u=mas/yr}})[6] and the fourth-largest parallax ({{val|449|8|u=mas}})[3] of any known star or brown dwarf, meaning it is the fourth-closest extrasolar system to the Sun. It is also the coldest object of its type found in interstellar space, having a temperature in the range {{convert|225|to|260|K|C F}}. CharacterizationObservationsThe WISE object was detected in March 2013, and follow-up observations were taken by the Spitzer Space Telescope and the Gemini North telescope. The name WISE J085510.83−071442.5 includes the coordinates and indicates that the object is located in the constellation Hydra. Distance and proper motionBased on direct observations, WISE 0855−0714 has a large parallax, which specifically relates to its distance from the Solar System. This phenomenon results in a distance of around {{val|7.27|0.13|u=light-years}},[3] with a small margin of error due to the strength of the parallax effect and the clarity of observations. WISE 0855−0714's proper motion across the sky is also directly observed over time, causing it to stand out in the observations, but the proper motion is itself a combination of its speed in the galactic neighborhood relative to the Solar System as well as its proximity to the Solar System. If it were moving exactly as fast but farther away, if it were moving more slowly but closer, or if it were moving more quickly near to the Sun but moving at a high angle towards or away from the Sun, it would have a smaller proper motion. SpectrometryIts luminosity in different bands of the thermal infrared in combination with its absolute magnitude—because of its known distance—was used to place it in context of different models; the best characterization of its brightness was in the W2 band of {{val|4.6|u=µm}} at an apparent magnitude of {{val|13.89|0.05}}, though it was brighter into the deeper infrared.[6] Infrared images taken with the Magellan Baade Telescope suggest evidence of water clouds.[18] Model-derived understandingBased on models of brown dwarfs WISE 0855−0714's is estimated to have a mass of {{Jupiter mass|3 to 10|jup=y|link=yes}}. This mass is in the range of a sub-brown dwarf or other planetary-mass object. As of 2003, the International Astronomical Union considers an object with a mass above {{Jupiter mass|13|jup=y}}, capable of fusing deuterium, to be a brown dwarf. A lighter object and one orbiting another object is considered a planet.[20] So far this WISE object is alone, though it could be a rogue planet, something first identified in 2004 in the case of Cha 110913-773444.[21] Combining its luminosity, distance, and mass it is estimated to be the coldest-known brown dwarf, with a modeled effective temperature of {{convert|225|to|260|K|C F}}, depending on the model. See also{{Div col}}
References1. ^{{cite simbad |title=WISEA J085510.74-071442.5 |accessdate=15 May 2017}} [2][3][4][5][6]2. ^1 2 3 {{cite journal |title=Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun |journal=The Astrophysical Journal Letters |first=Kevin L. |last=Luhman |volume=786 |issue=2 |page=L18 |date=21 April 2014 |doi=10.1088/2041-8205/786/2/L18 |arxiv=1404.6501 |bibcode=2014ApJ...786L..18L}} 3. ^1 {{cite web |url=http://home.dtm.ciw.edu/users/boss/definition.html |title=Working Group on Extrasolar Planets: Definition of a "Planet" |publisher=Working Group on Extrasolar Planets of the International Astronomical Union |date=28 February 2003 |accessdate=28 April 2014}} 4. ^1 {{cite news |url=http://www.americaspace.com/?p=59133 |title=Between the Planet and the Star: A New Ultra-Cold, Sub-Stellar Object Discovered Close to Sun |work=AmericaSpace.com |first=Leonidas |last=Papadopoulos |date=28 April 2014 |accessdate=28 April 2014}} 5. ^1 {{cite journal |title=Indications of Water Clouds in the Coldest Known Brown Dwarf |journal=Astrophysical Journal Letters |first1=Jacqueline K. |last1=Faherty |first2=C. G. |last2=Tinney |first3=Andrew |last3=Skemer |first4=Andrew J. |last4=Monson |date=August 2014 |arxiv=1408.4671 |bibcode=2014ApJ...793L..16F |doi=10.1088/2041-8205/793/1/L16}} 6. ^1 2 3 4 5 6 7 {{cite journal |title=The Spectral Energy Distribution of the Coldest Known Brown Dwarf |journal=The Astronomical Journal |first1=Kevin L. |last1=Luhman |first2=Taran L. |last2=Esplin |volume=152 |issue=2 |at=78 |date=September 2016 |doi=10.3847/0004-6256/152/3/78 |bibcode=2016AJ....152...78L |arxiv=1605.06655}} }} Further reading
External links
7 : Astronomical objects discovered in 2013|Hydra (constellation)|Local Bubble|WISE objects|Y-type stars|Brown dwarfs|Rogue planets |
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