scholarly journals The SOPHIE search for northern extrasolar planets

2018 ◽  
Vol 618 ◽  
pp. A103 ◽  
Author(s):  
M. J. Hobson ◽  
R. F. Díaz ◽  
X. Delfosse ◽  
N. Astudillo-Defru ◽  
I. Boisse ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Extrasolar Planets ◽  
Habitable Zone ◽  
Minimum Mass ◽  
Velocity Measurements ◽  
High Eccentricity ◽  
Dwarf Stars ◽  
M Stars ◽  
M Dwarf Stars ◽  
M Dwarf

We report the detection of two exoplanets and a further tentative candidate around the M-dwarf stars Gl96 and Gl617A, based on radial velocity measurements obtained with the SOPHIE spectrograph at the Observatoire de Haute-Provence. Both stars were observed in the context of the SOPHIE exoplanet consortium’s dedicated M-dwarf subprogramme, which aims to detect exoplanets around nearby M-dwarf stars through a systematic survey. For Gl96 we present the discovery of a new exoplanet at 73.9 d with a minimum mass of 19.66 earth masses. Gl96 b has an eccentricity of 0.44, placing it among the most eccentric planets orbiting M stars. For Gl617A we independently confirm a recently reported exoplanet at 86.7 d with a minimum mass of 31.29 earth masses. Both Gl96 b and Gl617A b are potentially within the habitable zone, although the high eccentricity of Gl96 b may take it too close to the star at periapsis.

scholarly journals The habitability of stagnant-lid Earths around dwarf stars

2019 ◽  
Vol 625 ◽  
pp. A12 ◽  
Author(s):  
Mareike Godolt ◽  
Nicola Tosi ◽  
Barbara Stracke ◽  
John Lee Grenfell ◽  
Thomas Ruedas ◽  
...  
Keyword(s):  
Water Loss ◽  
Main Sequence ◽  
Extrasolar Planets ◽  
Water Reservoir ◽  
Habitable Zone ◽  
High Luminosity ◽  
Dwarf Stars ◽  
Surface Conditions ◽  
M Dwarf Stars ◽  
M Dwarf

Context. The habitability of a planet depends on various factors, such as the delivery of water during its formation, the co-evolution of the interior and the atmosphere, and the stellar irradiation which changes in time. Aims. Since an unknown number of rocky extrasolar planets may operate in a one-plate convective regime, i.e. without plate tectonics, our aim is to understand the conditions under which planets in such a stagnant-lid regime may support habitable surface conditions. Understanding the interaction of the planetary interior and outgassing of volatiles in combination with the evolution of the host star is crucial to determining the potential habitability. M-dwarf stars in particular possess a high-luminosity pre-main sequence phase that endangers the habitability of planets around them via water loss. We therefore explore the potential of secondary outgassing from the planetary interior to rebuild a water reservoir allowing for habitability at a later stage. Methods. We compute the boundaries of the habitable zone around M-, K-, G-, and F-dwarf stars using a 1D cloud-free radiative-convective climate model accounting for the outgassing history of CO2 and H2O from an interior evolution and outgassing model for different interior compositions and stellar luminosity evolutions. Results. The outer edge of the habitable zone strongly depends on the amount of CO2 outgassed from the interior, while the inner edge is mainly determined via the stellar irradiation, as soon as a sufficiently large water reservoir has been outgassed. A build-up of a secondary surface and atmospheric water reservoir for planets around M-dwarf stars is possible even after severe water loss during the high-luminosity pre-main sequence phase as long as some water has been retained within the mantle. For small mantle water reservoirs, between 62 and 125 ppm, a time delay in outgassing from the interior permits such a secondary water reservoir build-up especially for early and mid-M dwarfs because their pre-main sequence lifetimes are shorter than the outgassing timescale. Conclusions. We show that Earth-like stagnant-lid planets allow for habitable surface conditions within a continuous habitable zone that is dependent on interior composition. Secondary outgassing from the interior may allow for habitability of planets around M-dwarf stars after severe water loss during the high-luminosity pre-main sequence phase by rebuilding a surface water reservoir.

scholarly journals The SOPHIE search for northern extrasolar planets

2019 ◽  
Vol 625 ◽  
pp. A18 ◽  
Author(s):  
M. J. Hobson ◽  
X. Delfosse ◽  
N. Astudillo-Defru ◽  
I. Boisse ◽  
R. F. Díaz ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Extrasolar Planets ◽  
Lower Boundary ◽  
Minimum Mass ◽  
Velocity Measurements ◽  
M Dwarfs ◽  
High Eccentricity ◽  
Solar Metallicity ◽  
History Of ◽  
M Dwarf

We present the detection of a warm Neptune orbiting the M dwarf Gl 378, using radial velocity measurements obtained with the SOPHIE spectrograph at the Observatoire de Haute-Provence. The star was observed in the context of the SOPHIE exoplanet consortium’s sub-programme dedicated to finding planets around M dwarfs. Gl 378 is an M1 star, of solar metallicity, at a distance of 14.96 pc. The single planet detected, Gl 378 b, has a minimum mass of 13.02 MEarth and an orbital period of 3.82 days, which place it at the lower boundary of the hot Neptune desert. As one of only a few such planets around M dwarfs, Gl 378 b provides important clues to the evolutionary history of these close-in planets. In particular, the eccentricity of 0.1 may point to a high-eccentricity migration. The planet may also have lost part of its envelope due to irradiation.

scholarly journals An Astrobiological Experiment to Explore the Habitability of Tidally Locked M-Dwarf Planets

2012 ◽  
Vol 8 (S293) ◽  
pp. 192-196
Author(s):  
Daniel Angerhausen ◽  
Haley Sapers ◽  
Eugenio Simoncini ◽  
Stefanie Lutz ◽  
Marcelo da Rosa Alexandre ◽  
...  
Keyword(s):  
Academic Research ◽  
Environmental Parameters ◽  
Climate Simulation ◽  
Habitable Zone ◽  
Dwarf Stars ◽  
Dwarf Planets ◽  
Late Type Star ◽  
M Dwarf Stars ◽  
M Dwarf ◽  
Simulation Chamber

AbstractWe present a summary of a three-year academic research proposal drafted during the Sao Paulo Advanced School of Astrobiology (SPASA) to prepare for upcoming observations of tidally locked planets orbiting M-dwarf stars. The primary experimental goal of the suggested research is to expose extremophiles from analogue environments to a modified space simulation chamber reproducing the environmental parameters of a tidally locked planet in the habitable zone of a late-type star. Here we focus on a description of the astronomical analysis used to define the parameters for this climate simulation.

scholarly journals Searching for Planetary Companions to Ultracool Dwarfs: Planet Hunting in the Near Infrared

2008 ◽  
Vol 4 (S253) ◽  
pp. 346-349
Author(s):  
Cullen H. Blake ◽  
David Charbonneau ◽  
David W. Latham
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Extrasolar Planets ◽  
Terrestrial Planets ◽  
Habitable Zone ◽  
Velocity Measurements ◽  
Ultracool Dwarfs

AbstractOwing to their small masses and radii, Ultracool Dwarfs (UCDs; late-M, L, and T dwarfs) may be excellent targets for planet searches and may afford astronomers the opportunity to detect terrestrial planets in the habitable zone. The precise measurements necessary to detect extrasolar planets orbiting UCDs represent a major challenge. We describe two efforts to obtain precise measurements of UCDs in the Near Infrared (NIR). The first involves the robotic NIR observatory PAIRITEL and efforts to obtain photometric precision sufficient for the detection of terrestrial planets transiting UCDs. The second effort involves precise radial velocity measurements of UCDs in the NIR and a survey undertaken with the NIRSPEC spectrograph on Keck.

scholarly journals Why do we find ourselves around a yellow star instead of a red star?

2017 ◽  
Vol 17 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Jacob Haqq-Misra ◽  
Ravi Kumar Kopparapu ◽  
Eric T. Wolf
Keyword(s):  
Bayesian Inference ◽  
Habitable Zone ◽  
M Dwarfs ◽  
Dwarf Stars ◽  
Habitable Planets ◽  
Chance Event ◽  
The Future ◽  
M Dwarf Stars ◽  
M Dwarf

AbstractM-dwarf stars are more abundant than G-dwarf stars, so our position as observers on a planet orbiting a G-dwarf raises questions about the suitability of other stellar types for supporting life. If we consider ourselves as typical, in the anthropic sense that our environment is probably a typical one for conscious observers, then we are led to the conclusion that planets orbiting in the habitable zone of G-dwarf stars should be the best place for conscious life to develop. But such a conclusion neglects the possibility that K-dwarfs or M-dwarfs could provide more numerous sites for life to develop, both now and in the future. In this paper we analyse this problem through Bayesian inference to demonstrate that our occurrence around a G-dwarf might be a slight statistical anomaly, but only the sort of chance event that we expect to occur regularly. Even if M-dwarfs provide more numerous habitable planets today and in the future, we still expect mid G- to early K-dwarfs stars to be the most likely place for observers like ourselves. This suggests that observers with similar cognitive capabilities as us are most likely to be found at the present time and place, rather than in the future or around much smaller stars.

scholarly journals Response of Atmospheric Biomarkers to NOx-Induced Photochemistry Generated by Stellar Cosmic Rays for Earth-like Planets in the Habitable Zone of M Dwarf Stars

Astrobiology ◽  
2012 ◽  
Vol 12 (12) ◽  
pp. 1109-1122 ◽  
Author(s):  
John Lee Grenfell ◽  
Jean-Mathias Grießmeier ◽  
Philip von Paris ◽  
A. Beate C. Patzer ◽  
Helmut Lammer ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Habitable Zone ◽  
Dwarf Stars ◽  
Earth Like Planets ◽  
M Dwarf Stars ◽  
M Dwarf

scholarly journals Activity-Induced Radial Velocity Variation of M Dwarf Stars

2012 ◽  
Vol 8 (S293) ◽  
pp. 197-200
Author(s):  
Jan Marie Andersen ◽  
Heidi Korhonen
Keyword(s):  
Radial Velocity ◽  
Magnetic Activity ◽  
Velocity Variation ◽  
M Dwarfs ◽  
Dwarf Stars ◽  
Highly Active ◽  
Radial Velocity Variation ◽  
Low Mass ◽  
M Dwarf Stars ◽  
M Dwarf

AbstractStellar magnetic activity manifests itself in a variety of ways including starspots–cool, dark regions on the stellar surface. Starspots can cause variations (‘jitter’) in spectral line-profiles which can mimic the radial velocity (RV) variations caused by an orbiting planet, or create RV noise that can drown out a planetary signature. Cool, low-mass M dwarf stars can be highly active, which can make detection of potentially habitable planets around these stars difficult. We investigate radial velocity variations caused by different activity (spot) patterns on M dwarf stars in order to determine the limits of detectability for small planets orbiting active M dwarfs. We report on our progress toward the aim of answering the following questions: What types of spot patterns are realistic for M dwarf stars? What effect will spots have on M dwarf RV measurements? Can jitter from M dwarf spots mimic planetary signals? What is the ideal observing wavelength to reduce M dwarf jitter?

Coronal Structure in M Dwarf Stars

1996 ◽  
pp. 81-82
Author(s):  
M. S. Giampapa ◽  
R. Rosner ◽  
V. Kashyap ◽  
T. A. Fleming ◽  
J. H. M. M. Schmitt ◽  
...  
Keyword(s):  
Coronal Structure ◽  
Dwarf Stars ◽  
M Dwarf Stars ◽  
M Dwarf

scholarly journals New Pulse Timing Measurements of the sdBV Star CS 1246

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Zackary L. Hutchens ◽  
Brad N. Barlow ◽  
Alan Vasquez Soto ◽  
Dan E. Reichart ◽  
Josh B. Haislip ◽  
...  
Keyword(s):  
Radial Pulsation ◽  
Minimum Mass ◽  
Velocity Measurements ◽  
Pulse Timing ◽  
Gravitational Influence ◽  
Low Mass ◽  
Robotic Telescope ◽  
M Dwarf ◽  
Long Term Trend

AbstractCS 1246 is a hot subdwarf B star discovered in 2009 to exhibit a single, large-amplitude radial pulsation. An O-C diagram constructed from this mode revealed reflex motion due to the presence of a low-mass M dwarf, as well as a long-term trend consistent with a decrease in the pulsational period. The orbital reflex motion was later confirmed with radial velocity measurements. Using eight years of data collected with the Skynet Robotic Telescope Network, we show that the pulsation amplitude of CS 1246 is decaying nonlinearly. We also present an updated O-C diagram, which might now indicate a positive Ṗ and a new 2.09 ± 0.05 yr oscillation consistent with orbital reflex motion of the entire inner sdB+dM binary, possibly due to the gravitational influence of a circumbinary planet with minimum mass

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