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Possibility for albedo estimation of exomoons: Why should we care about M dwarfs?
- Publication Year :
- 2016
-
Abstract
- Occultation light curves of exomoons may give information on their albedo and hence indicate the presence of ice cover on the surface. Icy moons might have subsurface oceans thus these may potentially be habitable. The objective of our paper is to determine whether next generation telescopes will be capable of albedo estimations for icy exomoons using their occultation light curves. The success of the measurements depends on the depth of the moon's occultation in the light curve and on the sensitivity of the used instruments. We applied simple calculations for different stellar masses in the V and J photometric bands, and compared the flux drop caused by the moon's occultation and the estimated photon noise of next generation missions with 5 $\sigma$ confidence. We found that albedo estimation by this method is not feasible for moons of solar-like stars, but small M dwarfs are better candidates for such measurements. Our calculations in the J photometric band show that E-ELT MICADO's photon noise is just about 4 ppm greater than the flux difference caused by a 2 Earth-radii icy satellite in a circular orbit at the snowline of an 0.1 stellar mass star. However, considering only photon noise underestimates the real expected noise, because other noise sources, such as CCD read-out and dark signal become significant in the near infrared measurements. Hence we conclude that occultation measurements with next generation missions are far too challenging, even in the case of large, icy moons at the snowline of small M dwarfs. We also discuss the role of the parameters that were neglected in the calculations, e.g. inclination, eccentricity, orbiting direction of the moon. We predict that the first albedo estimations of exomoons will probably be made for large icy moons around the snowline of M4 -- M9 type main sequence stars.<br />Comment: 13 pages, 6 figures, accepted for publication in A&A
- Subjects :
- Physics
010504 meteorology & atmospheric sciences
Stellar mass
Astrophysics::Instrumentation and Methods for Astrophysics
Astronomy and Astrophysics
Astrophysics
Icy moon
Light curve
01 natural sciences
Occultation
Stars
Space and Planetary Science
0103 physical sciences
Snow line
Circular orbit
Astrophysics::Earth and Planetary Astrophysics
010303 astronomy & astrophysics
Main sequence
Physics::Atmospheric and Oceanic Physics
0105 earth and related environmental sciences
Astrophysics - Earth and Planetary Astrophysics
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....3bfe0a57feb16df7d9b33f7b32b53338