Produção Nacional
Revisado por pares
A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation
2011; Nature Portfolio; Volume: 478; Issue: 7370 Linguagem: Inglês
10.1038/nature10550
ISSN1476-4687
AutoresB. Sicardy, J. L. Ortiz, M. Assafin, Emmanuël Jehin, A. Maury, E. Lellouch, R. Gil-Hutton, F. Braga-Ribas, F. Colas, Daniel Hestroffer, J. Lecacheux, Françoise Roques, P. Santos-Sanz, Thomas Widemann, N. Morales, R. Duffárd, Audrey Thirouin, A. J. Castro–Tirado, M. Jelínek, P. Kubánek, A. Sota, R. Sánchez-Ramírez, A. H. Andrei, J. I. B. Camargo, D. N. da Silva Neto, A. R. Gomes-Júnior, R. Vieira Martins, M. Gillon, Jean Manfroid, G. P. Tozzi, C. Harlingten, S. Saravia, R. Behrend, S. Mottola, Enrique García Melendo, Vicente Bodí Peris, J. Fabregat, J. M. Madiedo, L. Cuesta, M. T. Eibe, A. Ullán, F. Organero, S. Pastor, J.A. de los Reyes, S. Pedraz, Ana I. Gómez de Castro, I. de la Cueva, G. Muler, I. A. Steele, Manuel Cebrián, P. Montañés‐Rodríguez, A. Oscoz, Donald W. Weaver, C. Jacques, W. J. B. Corradi, Fábio P. Santos, Wilson Reis, A. Milone, M. Emílio, L. Gutiérrez, R. Vázquez, H. M. Hernández-Toledo,
Tópico(s)Planetary Science and Exploration
ResumoFour trans-Neptunian objects are currently recognized as dwarf planets: Eris, Haumea, Makemake and Pluto. Of these, the 'demoted' planet Pluto has been studied for many years and has a detected atmosphere. The others are difficult to observe because of their extreme distance from the Sun, but a stellar occultation event on 6 November 2010 provided an opportunity for a closer look at Eris. The data obtained reveal Eris as a 'twin' for Pluto in terms of size, and previous work showed the two to have similar surface compositions. Eris, however, has no detectable atmosphere and its surface is bright, possibly a result of atmospheric collapse in an extremely cold environment. The dwarf planet Eris is a trans-Neptunian object with an orbital eccentricity of 0.44, an inclination of 44 degrees and a surface composition very similar to that of Pluto1. It resides at present at 95.7 astronomical units (1 au is the Earth-Sun distance) from Earth, near its aphelion and more than three times farther than Pluto. Owing to this great distance, measuring its size or detecting a putative atmosphere is difficult. Here we report the observation of a multi-chord stellar occultation by Eris on 6 November 2010 ut. The event is consistent with a spherical shape for Eris, with radius 1,163 ± 6 kilometres, density 2.52 ± 0.05 grams per cm3 and a high visible geometric albedo, . No nitrogen, argon or methane atmospheres are detected with surface pressure larger than ∼1 nanobar, about 10,000 times more tenuous than Pluto's present atmosphere2,3,4,5. As Pluto's radius is estimated3,4,5,6,7,8 to be between 1,150 and 1,200 kilometres, Eris appears as a Pluto twin, with a bright surface possibly caused by a collapsed atmosphere, owing to its cold environment. We anticipate that this atmosphere may periodically sublimate as Eris approaches its perihelion, at 37.8 astronomical units from the Sun.
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