Albedo and atmospheric constraints of dwarf planet Makemake from a stellar occultation
- 21 November 2012
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature
- Vol. 491 (7425), 566-569
- https://doi.org/10.1038/nature11597
Abstract
The icy dwarf planet Makemake has projected axes of 1,430 ± 9 and 1,502 ± 45 km and a V-band geometric albedo larger than Pluto’s but smaller than Eris’s, with no global Pluto-like atmosphere. Makemake is thought to be the third-largest dwarf planet in our Solar System, a little smaller than Pluto and Eris, but until now knowledge of its size and albedo were only approximate. This paper reports the results of observations of the occultation of a faint star known as NOMAD 1181-0235723 by Makemake on 23 April 2011. The data confirm that Makemake is smaller than Pluto and Eris, with axes of 1,430±9 km and 1,502±45 km. Makemake's mean geometric albedo — the ratio of light reflected to light received — is intermediate between that of Pluto and that of Eris. All three are icy, making them among the most reflective objects in the Solar System. And the occultation light curves rule out the presence of a global Pluto-like atmosphere on Makemake, although the presence of dark terrain might imply the presence of a localized atmosphere. Pluto and Eris are icy dwarf planets with nearly identical sizes, comparable densities and similar surface compositions as revealed by spectroscopic studies1,2. Pluto possesses an atmosphere whereas Eris does not; the difference probably arises from their differing distances from the Sun, and explains their different albedos3. Makemake is another icy dwarf planet with a spectrum similar to Eris and Pluto4, and is currently at a distance to the Sun intermediate between the two. Although Makemake’s size (1,420 ± 60 km) and albedo are roughly known5,6, there has been no constraint on its density and there were expectations that it could have a Pluto-like atmosphere4,7,8. Here we report the results from a stellar occultation by Makemake on 2011 April 23. Our preferred solution that fits the occultation chords corresponds to a body with projected axes of 1,430 ± 9 km (1σ) and 1,502 ± 45 km, implying a V-band geometric albedo pV = 0.77 ± 0.03. This albedo is larger than that of Pluto, but smaller than that of Eris. The disappearances and reappearances of the star were abrupt, showing that Makemake has no global Pluto-like atmosphere at an upper limit of 4–12 nanobar (1σ) for the surface pressure, although a localized atmosphere is possible. A density of 1.7 ± 0.3 g cm−3 is inferred from the data.This publication has 23 references indexed in Scilit:
- The spectrum of (136199) Eris between 350 and 2350 nm: results with X-ShooterAstronomy & Astrophysics, 2011
- THE ROTATION PERIOD AND LIGHT-CURVE AMPLITUDE OF KUIPER BELT DWARF PLANET 136472 MAKEMAKE (2005 FY9)The Astronomical Journal, 2009
- Which are the dwarfs in the Solar System?Icarus, 2008
- Short-term rotational variability in the large TNO 2005FY9Astronomy & Astrophysics, 2007
- Volatile Loss and Retention on Kuiper Belt ObjectsThe Astrophysical Journal, 2007
- Satellites of the Largest Kuiper Belt ObjectsThe Astrophysical Journal, 2006
- The methane ice rich surface of large TNO 2005 FY9: a Pluto-twin in the trans-neptunian belt?Astronomy & Astrophysics, 2006
- Photometry of pluto in the last decade and before: evidence for volatile transport?Icarus, 2003
- Occultation evidence for an atmosphere on PlutoNature, 1988
- Occultation of Epsilon Geminorum by Mars. II - The structure and extinction of the Martian upper atmosphereThe Astrophysical Journal, 1977