Journal Article

A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation

Harlingten, C., Hutton, R. Gil, Castro, A., de la Cueva, I., Oscoz, A., Santos, F. P., Emilio, M., Steele, I. A., Gutiérrez, L., Kubánek, P., Corradi, W. J. B., Organero, F., Fabregat, J., Cuesta, L., Camargo, J. I. B., Sicardy, B., Peris, V., de los Reyes, J. A., Maury, A., Eibe, M. T., Gomes, A. Ramos, Duffard, R., Colas, F., Melendo, E. García, Vázquez, R., Jehin, E., Castro-Tirado, A. J., Jacques, C., Behrend, R., Thirouin, A., Hernández-Toledo, H., Jelínek, M., Widemann, T., Santos-Sanz, P., Montañés-Rodríguez, P., Assafin, M., Lellouch, E., Gillon, M., Pedraz, S., Morales, N., Hestroffer, D., Ortiz, J. L., Andrei, A. H., Sota, A., Muler, G., Roques, F., Manfroid, J., Lecacheux, J., Tozzi, G. P., Reis, W., Milone, A., Pastor, S., Mottola, S., Cebrián, M., Braga-Ribas, F., Madiedo, J. M., Ullán, A., Martins, R. Vieira, Sánchez-Ramírez, R., da Silva Neto, D. N., Weaver, D., Saravia, S.

2011

Overview

Pluto's twin is out in the cold Four 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 Pluto 1 . 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 cm 3 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 atmosphere 2 , 3 , 4 , 5 . As Pluto's radius is estimated 3 , 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.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/33/445 / Albedo / Asteroids (minor planets) / Astronomical bodies / Astronomy / Astrophysics / Atmosphere / Atmospheres / Aérospatiale, astronomie & astrophysique / Barometric pressure / Density / Earth and Planetary Astrophysics / Earth, ocean, space / Eris (dwarf planet) / Exact sciences and technology / Humanities and Social Sciences / letter / multidisciplinary / Perihelions / Physical, chemical, mathematical & earth Sciences / Physics / Physique, chimie, mathématiques & sciences de la terre / Planets, their satellites and rings. Asteroids / Pluto / Satellites / Science / Science (multidisciplinary) / Sciences of the Universe / Solar system / Space science, astronomy & astrophysics / Studies / Telescopes