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An old disk still capable of forming a planetary system

Bergin, Edwin A. and Cleeves, L. Ilsedore and Gorti, Uma and Zhang, Ke and Blake, Geoffrey A. and Green, Joel D. and Andrews, Sean M. and Evans, Neal J., II and Henning, Thomas and Öberg, Karin and Pontoppidan, Klaus and Qi, Chunhua and Salyk, Colette and van Dishoeck, Ewine F. (2013) An old disk still capable of forming a planetary system. Nature, 493 (7434). pp. 644-646. ISSN 0028-0836.

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From the masses of the planets orbiting the Sun, and the abundance of elements relative to hydrogen, it is estimated that when the Solar System formed, the circumstellar disk must have had a minimum mass of around 0.01 solar masses within about 100 astronomical units of the star. (One astronomical unit is the Earth–Sun distance.) The main constituent of the disk, gaseous molecular hydrogen, does not efficiently emit radiation from the disk mass reservoir, and so the most common measure of the disk mass is dust thermal emission and lines of gaseous carbon monoxide. Carbon monoxide emission generally indicates properties of the disk surface, and the conversion from dust emission to gas mass requires knowledge of the grain properties and the gas-to-dust mass ratio, which probably differ from their interstellar values. As a result, mass estimates vary by orders of magnitude, as exemplified by the relatively old (3–10 million years) star TW Hydrae, for which the range is 0.0005–0.06 solar masses. Here we report the detection of the fundamental rotational transition of hydrogen deuteride from the direction of TW Hydrae. Hydrogen deuteride is a good tracer of disk gas because it follows the distribution of molecular hydrogen and its emission is sensitive to the total mass. The detection of hydrogen deuteride, combined with existing observations and detailed models, implies a disk mass of more than 0.05 solar masses, which is enough to form a planetary system like our own.

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URLURL TypeDescription ReadCube access
Zhang, Ke0000-0002-0661-7517
Blake, Geoffrey A.0000-0003-0787-1610
Pontoppidan, Klaus0000-0001-7552-1562
van Dishoeck, Ewine F.0000-0001-7591-1907
Additional Information:© 2013 Nature Publishing Group. Received 21 June; accepted 14 November 2012. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech and by the US National Science Foundation under grant 1008800. This paper makes use of the following Atacama Large Millimeter/submillimeter Array (ALMA) data: ADS/JAO.ALMA#2011.0.00001.SV. ALMA is a partnership of ESO (representing itsmember states), the NSF (USA) and NINS(Japan), together with the NRC (Canada) and the NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. Author Contributions: E.A.B., L.I.C., U.G. and K.Z. performed the detailed calculations used in the analysis. J.D.G. reduced the Herschel data. S.M.A. provided detailed disk physical models and U.G. provided thermochemical models, both developed specifically for TWHya. E.A.B. wrote the manuscript with revisions by N.J.E. All authors were participants in the discussion of results, determination of the conclusions and revision of the manuscript.
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Subject Keywords:Stars
Record Number:CaltechAUTHORS:20130221-102034874
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37048
Deposited By: Jason Perez
Deposited On:21 Feb 2013 22:36
Last Modified:21 Aug 2017 20:48

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