6 research outputs found
SPECULOOS exoplanet search and its prototype on TRAPPIST
One of the most significant goals of modern science is establishing whether
life exists around other suns. The most direct path towards its achievement is
the detection and atmospheric characterization of terrestrial exoplanets with
potentially habitable surface conditions. The nearest ultracool dwarfs (UCDs),
i.e. very-low-mass stars and brown dwarfs with effective temperatures lower
than 2700 K, represent a unique opportunity to reach this goal within the next
decade. The potential of the transit method for detecting potentially habitable
Earth-sized planets around these objects is drastically increased compared to
Earth-Sun analogs. Furthermore, only a terrestrial planet transiting a nearby
UCD would be amenable for a thorough atmospheric characterization, including
the search for possible biosignatures, with near-future facilities such as the
James Webb Space Telescope. In this chapter, we first describe the physical
properties of UCDs as well as the unique potential they offer for the detection
of potentially habitable Earth-sized planets suitable for atmospheric
characterization. Then, we present the SPECULOOS ground-based transit survey,
that will search for Earth-sized planets transiting the nearest UCDs, as well
as its prototype survey on the TRAPPIST telescopes. We conclude by discussing
the prospects offered by the recent detection by this prototype survey of a
system of seven temperate Earth-sized planets transiting a nearby UCD,
TRAPPIST-1.Comment: Submitted as a chapter in the "Handbook of Exoplanets" (editors: H.
Deeg & J.A. Belmonte; Section Editor: N. Narita). 16 pages, 4 figure
Circumstellar disks and planets. Science cases for next-generation optical/infrared long-baseline interferometers
We present a review of the interplay between the evolution of circumstellar
disks and the formation of planets, both from the perspective of theoretical
models and dedicated observations. Based on this, we identify and discuss
fundamental questions concerning the formation and evolution of circumstellar
disks and planets which can be addressed in the near future with optical and
infrared long-baseline interferometers. Furthermore, the importance of
complementary observations with long-baseline (sub)millimeter interferometers
and high-sensitivity infrared observatories is outlined.Comment: 83 pages; Accepted for publication in "Astronomy and Astrophysics
Review"; The final publication is available at http://www.springerlink.co
Variability of Brown Dwarfs
Brown dwarfs constitute a missing link between low-mass stars and giant
planets. Their atmospheres display chemical species typical of planets, and one
could wonder whether they also have weather-like patterns. While brown dwarf
surface features cannot be directly resolved, the photometric and spectroscopic
modulations induced by these features, as they rotate in and out of view,
provide a wealth of information on the evolution of their atmosphere. A review
of brown dwarfs variability through the L, T and Y spectral types sequence is
presented, as well as the constraints that they set on the nature of
weather-like patterns on their surface.Comment: Accepted chapter in the "Handbook of Exoplanets"; Springe
Photochemistry of Terrestrial Exoplanet Atmospheres
Terrestrial exoplanets are exciting objects to study because they could be potential habitats for extraterrestrial life. Both the search and the characterization of terrestrial exoplanets are flourishing. Particularly, NASA’s Kepler spacecraft has discovered Earth-sized planets receiving similar amount of radiative heat as Earth. Central in the studies of terrestrial exoplanets is to characterize their atmospheres and to search for potential biosignature gases (the atmospheric components that indicate biogenic surface emissions). To achieve this goal, a deep understanding of the key physical and chemical processes that control the atmospheric composition and the atmosphere-surface interaction is pivotal