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| {{Starbox begin
| | Hi there, I am Sophia. Some time ago he selected to reside in North Carolina and he doesn't plan on altering it. He works as a bookkeeper. Doing ballet is something she would by no means give up.<br><br>Feel free to surf to my webpage :: [http://www.sirudang.com/siroo_Notice/2110 good psychic] |
| | name = TW Hydrae
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| }}
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| {{Starbox observe
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| | epoch = [[J2000.0]]
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| | constell = [[Hydra (constellation)|Hydra]]
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| | ra = {{RA|11|01|52}}<ref name="SIMBAD"/>
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| | dec = {{DEC|-34|42|17}}<ref name="SIMBAD"/>
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| | appmag_v = {{nowrap|11.27 ± 0.09}}<ref name="SIMBAD"/>
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| }}
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| {{Starbox character
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| | type = [[Pre-main-sequence]]
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| | class = K6V:e<ref name="SIMBAD"/>
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| | r-i =
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| | v-r =
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| | b-v = 0.67<ref name="SIMBAD"/>
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| | u-b = -0.33<ref name="Mermilliod1991+2006"/><!--unreliable?-->
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| | j-h = 0.659<ref name="SIMBAD"/>
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| | j-k = 0.92<ref name="SIMBAD"/>
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| | variable =[[T Tauri star|T Tauri]]
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| }}
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| {{Starbox astrometry
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| | radial_v = {{nowrap|13.40 ± 0.8}}<ref name="SIMBAD"/>
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| | prop_mo_ra = {{nowrap|-66.19 ± 1.85}}<ref name="SIMBAD"/>
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| | prop_mo_dec = {{nowrap|-13.90 ± 1.47}}<ref name="SIMBAD"/>
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| | parallax = 18.62
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| | p_error = 2.14
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| | parallax_footnote=<ref name="SIMBAD"/>
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| }}
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| {{Starbox detail
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| | age_myr = 8<ref name="Rheeetal2007"/>
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| | metal =
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| | mass = 0.8<ref name="Chunhua2013"/>
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| | radius = 1.11<ref name="Rheeetal2007"/>
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| | gravity=
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| | rotation =
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| | luminosity_bolometric=0.28<ref group="note">From <math>\begin{smallmatrix}L=4 \pi R^2 \sigma T_{\rm eff}^4 \end{smallmatrix}</math>, where <math>\begin{smallmatrix}L \end{smallmatrix}</math> is the luminosity, <math>\begin{smallmatrix}R \end{smallmatrix}</math> is the radius, <math>\begin{smallmatrix}T_{\rm eff}\end{smallmatrix}</math> is the effective surface temperature and <math>\begin{smallmatrix}\sigma \end{smallmatrix}</math> is the [[Stefan–Boltzmann constant]].</ref>
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| | temperature = 4,000<ref name="Rheeetal2007"/>
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| }}
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| {{Starbox catalog
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| | names = [[Guide Star Catalog|GSC 07208-00347]], [[Hipparcos Catalogue|HIP 53911]]
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| }}
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| {{Starbox reference
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| | Simbad = TW+Hya
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| }}
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| {{Starbox end}}
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| '''TW Hydrae''' is an [[orange dwarf]] [[star]] approximately 176 [[light-year]]s away in the [[constellation]] of [[Hydra (constellation)|Hydra]] (the [[Sea Serpent]]). The star is the closest [[T Tauri star]] to the [[Solar System]]. TW Hydrae is about 80% of the [[mass]] of the Sun, but is only about 5-10 million years old. The star appears to be accreting from a face-on [[protoplanetary disk]] of dust and gas, which has been resolved in images from the [[Hubble Space Telescope]]. TW Hydrae is accompanied by about twenty other low-mass stars with similar ages and spatial motions, comprising the "[[TW Hydrae association]]" or TWA, one of the closest regions of recent "fossil" star-formation to the Sun.
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| == Planetary system ==
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| === Protoplanetary disk ===
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| [[File:Artist’s impression of snow lines around TW Hydrae.jpg|thumb|Artist’s impression of snow lines around TW Hydrae.<ref>{{cite news|title=Snow in an Infant Planetary System|url=http://www.eso.org/public/news/eso1333/|accessdate=21 July 2013|newspaper=ESO Press Release}}</ref> ]]
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| [[David Wilner]], an [[astrophysicist]] at the [[Harvard-Smithsonian Center for Astrophysics]], began examining TW Hydrae in the late 1990s, enabled by the new capabilities of telescopes. In 2005 he discovered that the [[gaseous]] disk surrounding TW Hydrae holds vast swathes of pebbles extending outward for at least one billion miles. The planet formation process, according to core-accretion theory, begins when dust grains in a disk collide and accrete to form larger and larger clumps. Eventually, after millions of years of colliding and combining, the clumps form planets.
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| Wilner and his colleagues used the [[National Science Foundation]] (NSF)-funded [[Very Large Array]] (VLA) radio telescope to measure the strength of [[radio waves]] emitted by TW Hydrae. Based on the relationship between [[wavelength]] and particle size, they determined the grainy materials surrounding the star to be [[centimeter]]-sized.
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| One of the collaborators, Mark Claussen of the [[National Radio Astronomy Observatory]], thought the strong and variable emissions detected from TW Hydrae in previous [[X-ray]] detections indicated [[magnetic]] activity common in young stars. Claussen thought that if they monitored TW Hydrae at radio wavelengths for a period of a few months, they could determine if the emissions might be strong enough to [[image]] at a much higher resolution with the NSF-funded [[Very Long Baseline Array]] and study this activity. To their surprise, they found that the [[radio]] emissions did not vary significantly.
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| He decided to revisit the VLA. The observatory's twenty-seven operating antennae are spread throughout the plains of San Augustin, N.M., and arranged in one of four configurations that are changed every few months. Wilner found the pebbles using a larger configuration and higher [[angular resolution]] of the VLA. He enlisted the help of Nuria Calvet, a colleague at the [[Center for Astrophysics]], who created a [[computer model]] of the disk surrounding TW Hydrae using previously published data.<ref>{{cite journal
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| | author = Wilner, D. J.; D'Alessio, P.; Calvet, N.; Claussen, M. J.; Hartmann, L.
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| | year = 2005
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| | journal = The Astrophysical Journal
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| | title = Toward Planetesimals in the Disk around TW Hydrae: 3.5 Centimeter Dust Emission
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| | volume = 626
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| | issue = 2
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| | pages = L109–L112
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| | bibcode = 2005ApJ...626L.109W
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| | doi = 10.1086/431757|arxiv = astro-ph/0506644 }}</ref>
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| Recently, Wilner collaborated with his [[graduate student]], Meredith Hughes, and several other colleagues to identify a hole in TW Hydrae's dusty disk. Wilner says that the hole was probably created when a [[Jupiter]]-sized planet cleared that gap of much of its rocky material. This latest research was accepted for publication by the [[Astrophysical Journal]] in April 2007.
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| Astronomers using the Herschel Space Observatory have discovered the equivalent of thousands of times the amount of water on earth in a planet-forming ring around the star. The water was in the form of relatively cold water vapor.<ref>[http://www.nasa.gov/mission_pages/herschel/news/herschel20111020.html Herschel Finds Oceans of Water in Disk of Nearby Star]</ref><ref>[http://www.jpl.nasa.gov/news/news.cfm?release=2011-327 Herschel Finds Oceans of Water in Disk of Nearby Star]</ref> The results were published in the October 21, 2011 issue of the journal ''Science''.<ref>Watery Disks by
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| Rachel Akeson Science 21 October 2011:
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| Vol. 334 no. 6054 pp. 316-317
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| DOI: 10.1126/science.1213752</ref>
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| === Disproven protoplanet ===
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| In December 2007, a team led by Johny Setiawan of the [[Max Planck Institute for Astronomy]] in [[Heidelberg]], [[Germany]] announced discovery of a planet orbiting TW Hydrae, dubbed "TW Hydrae b" with a minimum mass around 1.2 [[Jupiter mass]]es, a period of 3.56 days, and an orbital radius of 0.04 [[astronomical unit]]s (inside the inner rim of the protoplanetary disk). Assuming it orbits in the same plane as the outer part of thet dust disk ([[inclination]] 7±1°<ref name="setiawan08">{{cite journal|journal=Nature|volume= 451|pages= 38–41|date=3 January 2008| doi=10.1038/nature06426| title=A young massive planet in a star–disk system| first=J.| last= Setiawan| coauthors= Th. Henning, R. Launhardt, A. Müller, P. Weise & M. Kürster| url=http://www.nature.com/nature/journal/v451/n7174/abs/nature06426.html| format=abstract|pmid=18172492|issue=7174| bibcode=2008Natur.451...38S}}</ref>), it has a true mass of 9.8±3.3 Jupiter masses.<ref name="setiawan08" /><ref>{{cite news| url=http://space.newscientist.com/article/dn13135-first-planet-discovered-around-a-youthful-star.html | title=First planet discovered around a youthful star| date=2 January 2008| publisher= NewScientist.com news service| first= Maggie| last= McKee| accessdate=2008-01-02}}</ref> However if the inclination is similar to the inner part of the dust disk (4.3±1.0°<ref name="pontoppidan08">{{cite journal|title=Spectro-astrometric imaging of molecular gas within protoplanetary disk gaps|author=Pontoppidan, Klaus M. ''et al.''|year=2008|journal=[[The Astrophysical Journal]]|volume=684|issue=2|pages=1323–1329|doi=10.1086/590400|bibcode=2008ApJ...684.1323P|arxiv = 0805.3314 }}</ref>), the mass would be 16{{±|5|3}} Jupiter masses, making it a [[brown dwarf]].<ref name="pontoppidan08" /> Since the star itself is so young, it was presumed this is the youngest extrasolar planet yet discovered, and essentially still in formation.<ref>{{cite web|url=http://www.mpia.de/Public/menu_q2e.php?Aktuelles/PR/2008/PR080103/PR_080103_en.html|title=A young extrasolar planet in its cosmic nursery: Astronomers from Heidelberg discover planet in a dusty disk around a newborn star|date=2008-01-02|publisher=[[Max Planck Institute for Astronomy]]|accessdate=2008-01-03}}</ref>
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| In 2008 a team of Spanish researchers concluded that the planet does not exist: the radial velocity variations were not consistent when observed at different [[wavelength]]s, which would not occur if the origin of the radial velocity variations was caused by an orbiting planet. Instead, the data was better modelled by [[starspot]]s on TW Hydrae's surface passing in and out of view as the star rotates. "Results support the spot scenario rather than the presence of a hot Jupiter around TW Hya".<ref>{{cite journal|url=http://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2008/38/aa10596-08/aa10596-08.html|author=Huelamo, N. ''et al.''|title=TW Hydrae: evidence of stellar spots instead of a Hot Jupiter|journal=[[Astronomy and Astrophysics]]|volume=489|issue=2|pages=L9–L13|year=2008|accessdate=2008-10-02|doi=10.1051/0004-6361:200810596|bibcode=2008A&A...489L...9H|arxiv = 0808.2386 }}</ref> Similar wavelength-dependent radial velocity variations, also caused by starspots, have been detected on other T Tauri stars.<ref>{{cite journal|author=Prato, L. ''et al.''|title=A Young Planet Search in Visible and IR Light: DN Tau, V836 Tau, and V827 Tau|year=2008|journal=[[The Astrophysical Journal]]|volume=687|issue=2|pages=L103–L106|doi=10.1086/593201|bibcode=2008ApJ...687L.103P|arxiv = 0809.3599 }}</ref>
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| Based on scalings to previous hydrodynamic simulations of gap-opening criteria for embedded proto-planets, a planetary companion creating the gap could have a mass between 6–28 M<sub>⊕</sub> (orbital radius of 80 AU).<ref>[http://arxiv.org/pdf/1306.2969 The 0.5-2.22-micron Scattered Light Spectrum of the Disk Around TW Hya: Detection of a Partially Filled Disk Gap at 80 AU]</ref>
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| == Notes ==
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| {{reflist|group=note}}
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| == References ==
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| {{reflist|refs=
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| <ref name="SIMBAD">{{cite web | url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=TW+Hydrae | work=SIMBAD | title=V* TW Hya -- T Tau-type Star | publisher=Centre de Données astronomiques de Strasbourg | accessdate=2014-01-02 }}</ref>
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| <ref name="Rheeetal2007">{{citation | first1=J.H. | last1=Rhee | first2=I. | last2=Song | first3=B. | last3=Zuckerman | first4=M. | last4=McElwain |date=May 2007 | title=Characterization of dusty debris disks: the IRAS and Hipparcos catalogs | display-authors=1<!--Expandable--> | journal=The Astrophysical Journal | volume=660 | issue=2 | pages=1556-1571 | bibcode=2007ApJ...660.1556R | doi=10.1086/509912 | postscript=. |arxiv = astro-ph/0609555}}[http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ52c4e54377c1&-out.add=.&-source=J/ApJ/660/1556/table2&recno=72 Vizier catalog entry]</ref>
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| <ref name="Mermilliod1991+2006">{{citation | first=J.C. | last=Mermilliod | year=1991 | title=Homogeneous Means in the UBV System | publisher=Institut d'Astronomie, Universite de Lausanne | publication-date=1991 | bibcode=2006yCat.2168....0M | | postscript=. }}[http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ52c7867946de&-out.add=.&-source=II/168/ubvmeans&recno=76066 Vizier catalog entry]</ref>
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| <ref name="Chunhua2013">{{cite journal | first1=Qi | last1=Chunhua | first2=Karin I. | last2=Öberg | first3=David J. | last3=Wilner | first4=Paola| last4=D'Alessio | first5=Edwin | last5=Bergin | first6=Sean M. | last6= Andrews | first7=Geoffrey A. | last7=Blake | first8=Michiel R. | last8=Hogerheijde | first9=Ewine F. | last9=van Dishoeck |date=August 2013 | title=
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| Imaging of the CO Snow Line in a Solar Nebula Analog | display-authors=1<!--Expandable--> | journal=[[Science (journal)|Science]] | volume=341 | issue=6146 | pages=630-632 | bibcode=2013Sci...341..630Q | doi=10.1126/science.1239560 | postscript=. |arxiv = 1307.7439}}</ref>
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| }}
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| == External links ==
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| * {{cite web |url=http://www.spacetelescope.org/news/html/heic0501.html |title=Hubble's infrared eyes home in on suspected extrasolar planet |accessdate=2008-06-24 |work=[[NASA]] |publisher=[[Hubble Space Telescope]]}}
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| * {{cite web |url=http://exoplanet.eu/catalog/TW%20Hya_b |title=Notes for star TW Hya and possible planet TW Hya b |accessdate=2014-01-06 |work=The Extrasolar Planets Encyclopaedia}}
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| {{Stars of Hydra}}
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| [[Category:Hydra (constellation)]]
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| [[Category:K-type main-sequence stars]]
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| [[Category:T Tauri stars]]
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| [[Category:TW Hydrae association]]
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| [[Category:Variable stars]]
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| [[Category:Objects named with variable star designations|Hydrae, TW]]
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| [[Category:Objects within 1000 ly of Earth]]
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Hi there, I am Sophia. Some time ago he selected to reside in North Carolina and he doesn't plan on altering it. He works as a bookkeeper. Doing ballet is something she would by no means give up.
Feel free to surf to my webpage :: good psychic