scholarly journals Suppression of the Water Ice and Snow Albedo Feedback on Planets Orbiting Red Dwarf Stars and the Subsequent Widening of the Habitable Zone

Astrobiology ◽  
2012 ◽  
Vol 12 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Manoj M. Joshi ◽  
Robert M. Haberle
Keyword(s):  
Habitable Zone ◽  
Dwarf Stars ◽  
Albedo Feedback ◽  
Snow Albedo ◽  
Water Ice ◽  
Red Dwarf Stars

ENVIRONMENTAL EFFECTS OF FLARES FROM RED DWARF STARS

2011 ◽  
Vol 20 (supp02) ◽  
pp. 37-41
Author(s):  
LIUBA PEÑATE ◽  
ROLANDO CÁRDENAS ◽  
OSMEL MARTÍN
Keyword(s):  
Environmental Effects ◽  
Life Forms ◽  
Habitable Zone ◽  
Dwarf Stars ◽  
Planet Surface ◽  
Star Evolution ◽  
Stellar Flares ◽  
Red Dwarfs ◽  
Red Dwarf Stars ◽  
Radiative Perturbation

We examine some environmental effects appearing on exoplanets in the habitable zone of red dwarfs, during the first billion years of the star evolution. We focus on the radiative perturbation that the frequent stellar flares would cause on the planet surface and down the assumed planetary ocean, with some insight on the affectation of potential life forms.

Flaring red dwarf stars: news from Crimea

1998 ◽  
Vol 168 (8) ◽  
pp. 891 ◽  
Author(s):  
Roald E. Gershberg
Keyword(s):  
Dwarf Stars ◽  
Red Dwarf Stars

scholarly journals Turbulent Sound Generation in Red Dwarf Stars

1983 ◽  
Vol 71 ◽  
pp. 605-608
Author(s):  
H.U. Bonn
Keyword(s):  
Current Model ◽  
Solar Chromosphere ◽  
Sound Generation ◽  
Dwarf Star ◽  
Dwarf Stars ◽  
Model Calculations ◽  
Red Dwarf Stars

Since the acoustic heating theory (c.f. Ulmschneider 1979) has been proven successful for the solar chromosphere, it was common practice to extend this concept to other stars. However, as it appeares from observed chromospheric and coronal emissions, the usual theoretical acoustic fluxes for red dwarf star, particularly, are too small to account for the heating of chromospheres and coronae (e.g. Blanco et al 1974; Vaiana et al, 198l) . It is therefore the intention of this paper to discuss improvements on the current model calculations for turbulent sound generation from outer convection zones.

scholarly journals Double-Peaked Flare Events on red Dwarf Stars and Solar ‘Sympathetic’ Flares

1976 ◽  
Vol 71 ◽  
pp. 475-475
Author(s):  
M. Rodonò
Keyword(s):  
Proximity Effect ◽  
Binary Systems ◽  
Angular Separation ◽  
Dwarf Stars ◽  
Multiple Systems ◽  
Photometric Observations ◽  
Red Dwarfs ◽  
Flare Stars ◽  
Red Dwarf Stars ◽  
The Individual

About 50% of the flare events observed on red dwarfs are at least double-peaked. As the majority of flare stars are members of double or multiple systems, the possibility that time-overlapping flares originate quasi-simultaneously on the individual components is discussed.Assuming a poissonian occurrence of flares in both components, the expected probability of observing double-peaked flares is lower than 1% for the most active binary systems.However, from photometric observations of the double flare star EQ Peg (BD +19°5116 AB) carried out by the author with an area scanner (the components' angular separation is 3.7″) about 20% of the observed flares have been found to be double-peaked flares resulting from separate flares, one in each component. A direct flare triggering of the following flare by the preceding one can be ruled out since the light travel-time between the two components is 3.5 h, while the observed time delay between the flare peaks is about 10 min. Moreover, the proximity effect does not seem to play an important triggering role.It is concluded that, although the analogy with solar ‘sympathetic’ flares is not always applicable, it is the most promising framework within which the majority of double-peaked flare events on red dwarfs must be interpreted.

Snow-albedo feedback and Swiss spring temperature trends

2012 ◽  
Vol 110 (4) ◽  
pp. 509-516 ◽  
Author(s):  
S. C. Scherrer ◽  
P. Ceppi ◽  
M. Croci-Maspoli ◽  
C. Appenzeller
Keyword(s):  
Spring Temperature ◽  
Albedo Feedback ◽  
Snow Albedo ◽  
Temperature Trends

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 Speckle Interferometry of Red Dwarf Stars

2018 ◽  
Vol 155 (5) ◽  
pp. 215 ◽  
Author(s):  
Brian D. Mason ◽  
William I. Hartkopf ◽  
Korie N. Miles ◽  
John P. Subasavage ◽  
Deepak Raghavan ◽  
...  
Keyword(s):  
Speckle Interferometry ◽  
Dwarf Stars ◽  
Red Dwarf Stars

scholarly journals The ITA Survey on Red Dwarf Variable Stars – Final Report

1983 ◽  
Vol 71 ◽  
pp. 175-177
Author(s):  
C.A.O. Torres ◽  
I.C. Busko ◽  
G.R. Quast
Keyword(s):  
Variable Stars ◽  
Final Report ◽  
Dwarf Stars ◽  
Red Dwarf Stars ◽  
Almost All

From 1971 to 1973, an observational survey on red dwarf stars to search for possible periodic photometric variations was carried out at ITA Observatory - Brazil. Two observing runs at Cerro Tololo in 1974 and 1975 were used as an extension of this survey. We observed a total of 90 stars, as shown in Table I, and almost all stars were measured at least five times during the same season.

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.

Properties of Radiative Shock Waves in the Atmospheres of Red Dwarf Stars

Astrophysics ◽  
2019 ◽  
Vol 62 (2) ◽  
pp. 234-250 ◽  
Author(s):  
O. M. Belova ◽  
K. V. Bychkov
Keyword(s):  
Shock Waves ◽  
Dwarf Stars ◽  
Radiative Shock ◽  
Red Dwarf Stars
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