MODELING THE INFRARED SPECTRUM OF THE EARTH-MOON SYSTEM: IMPLICATIONS FOR THE DETECTION AND CHARACTERIZATION OF EARTHLIKE EXTRASOLAR PLANETS AND THEIR MOONLIKE COMPANIONS

Journal Article · Tue Nov 01 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/741/1/51; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21612725

Robinson, Tyler D., E-mail: [e-mail] ^[1]

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1. NASA Astrobiology Institute. (United States)

The Moon maintains large surface temperatures on its illuminated hemisphere and can contribute significant amounts of flux to spatially unresolved thermal infrared (IR) observations of the Earth-Moon system, especially at wavelengths where Earth's atmosphere is absorbing. In this paper we investigate the effects of an unresolved companion on IR observations of Earthlike exoplanets. For an extrasolar twin Earth-Moon system observed at full phase at IR wavelengths, the Moon consistently comprises about 20% of the total signal, approaches 30% of the signal in the 9.6 {mu}m ozone band and the 15 {mu}m carbon dioxide band, makes up as much as 80% of the signal in the 6.3 {mu}m water band, and more than 90% of the signal in the 4.3 {mu}m carbon dioxide band. These excesses translate to inferred brightness temperatures for Earth that are too large by 20-40 K and demonstrate that the presence of undetected satellites can have significant impacts on the spectroscopic characterization of exoplanets. The thermal flux contribution from an airless companion depends strongly on phase, implying that observations of exoplanets should be taken when the star-planet-observer angle (i.e., phase angle) is as large as feasibly possible if contributions from companions are to be minimized. We show that, by differencing IR observations of an Earth twin with a companion taken at both gibbous and crescent phases, Moonlike satellites may be detectable by future exoplanet characterization missions for a wide range of system inclinations.

• OSTI ID: 21612725
• Journal Information: Astrophysical Journal, Vol. 741, Issue 1; Other Information: DOI: 10.1088/0004-637X/741/1/51; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BRIGHTNESS
CARBON DIOXIDE
DETECTION
EARTH ATMOSPHERE
INCLINATION
INFRARED SPECTRA
MOON
OZONE
PLANETS
SIGNALS
SIMULATION
SOLAR SYSTEM
SOLAR SYSTEM EVOLUTION
STARS
WAVELENGTHS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
EVOLUTION
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SATELLITES
SPECTRA