Search results for "Terrestrial planet"
showing 4 items of 4 documents
GJ 357 b: A Super-Earth Orbiting an Extremely Inactive Host Star
2020
Aims. In this paper we present a deep X-ray observation of the nearby M dwarf GJ 357 and use it to put constraints on the atmospheric evolution of its planet, GJ 357 b. We also analyse the systematic errors in the stellar parameters of GJ 357 in order to see how they affect the perceived planetary properties. Methods. By comparing the observed X-ray luminosity of its host star, we estimate the age of GJ 357 b as derived from a recent XMM-Newton observation (log Lx [erg s-1] = 25.73), with Lx-age relations for M dwarfs. We find that GJ 357 presents one of the lowest X-ray activity levels ever measured for an M dwarf, and we put a lower limit on its age of 5 Gyr. Using this age limit, we perf…
Exploring Super-Earth Surfaces: Albedo of Near-Airless Magma Ocean Planets and Topography
2021
In this paper we propose an analytic function for the spherical albedo values of airless and near-airless magma ocean planets (AMOPs). We generated 2-D fractal surfaces with varying compositions onto which we individually threw 10,000 light rays. Using an approximate form of the Fresnel equations we measured how much of the incident light was reflected. Having repeated this algorithm on varying surface roughnesses we find the spherical albedo as a function of the Hurst exponent, the geochemical composition of the magma, and the wavelength. As a proof of concept, we used our model on Kepler-10b to demonstrate the applicability of our approach. We present the spherical albedo values produced …
Oxygen and the Exploration of the Universe
2010
Humankind has begun, in a tentative way, the immense project of exploring, and perhaps colonizing, other worlds. The grand enterprise has hardly begun and will certainly suffer many defeats and reversals, but it seems destined to go forward. In the course of this, both in seeking life in extraterrestrial environments and voyaging into them, we shall encounter a number of problems concerning the existence or provision of oxygen. The basis for this has been described in previous chapters. First, we would like to summarize arguments as to why life could have evolved on other planets. We need to know what to expect.
HADES RV Programme with HARPS-N at TNG. IV. Time resolved analysis of the Ca II H&K and Hα chromospheric emission of low-activity early-type M dwarfs
2016
Context. M dwarfs are prime targets for current and future planet search programs, particularly those focused on the detection and characterization of rocky planets in the habitable zone. In this context, understanding their magnetic activity is important for two main reasons: it affects our ability to detect small planets and it plays a key role in the characterization of the stellar environment. Aims: We analyze observations of the Ca II H&K and Hα lines as diagnostics of chromospheric activity for low-activity early-type M dwarfs. Methods: We analyze the time series of spectra of 71 early-type M dwarfs collected in the framework of the HADES project for planet search purposes. The HARPS-…