Titan and habitable planets around M-dwarfs

2010 ◽  
Vol 147 ◽  
pp. 405 ◽  
Author(s):  
Jonathan I. Lunine
Keyword(s):  
M Dwarfs ◽  
Habitable Planets

On the Growth and Detectability of Land Plants on Habitable Planets around M Dwarfs

Astrobiology ◽  
2017 ◽  
Vol 17 (12) ◽  
pp. 1219-1232 ◽  
Author(s):  
Duo Cui ◽  
Feng Tian ◽  
Yuwei Wang ◽  
Changshen Li ◽  
Chaoqing Yu ◽  
...  
Keyword(s):  
Land Plants ◽  
M Dwarfs ◽  
Habitable Planets

scholarly journals THE IMPACT OF STELLAR ROTATION ON THE DETECTABILITY OF HABITABLE PLANETS AROUND M DWARFS

2016 ◽  
Vol 821 (1) ◽  
pp. L19 ◽  
Author(s):  
Elisabeth R. Newton ◽  
Jonathan Irwin ◽  
David Charbonneau ◽  
Zachory K. Berta-Thompson ◽  
Jason A. Dittmann
Keyword(s):  
Stellar Rotation ◽  
M Dwarfs ◽  
Habitable Planets ◽  
The Impact

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 In situ models for planet assembly around cool stars

2014 ◽  
Vol 14 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Brad M. S. Hansen
Keyword(s):  
Water Content ◽  
Planetary System ◽  
Habitable Zone ◽  
Water Delivery ◽  
M Dwarfs ◽  
Transit Systems ◽  
Produce Water ◽  
Habitable Planets ◽  
Cool Stars

AbstractWe present a model for the in situ assembly of planetary systems around a 0.5 M⊙ star, and compare the resulting statistics with the observed sample of cool Kepler planet candidates. We are able to reproduce the distribution of planetary periods and period ratios, although we once again find an underabundance of single transit systems relative to the observations. We also demonstrate that almost every planetary system assembled in this fashion contains at least one planet in the habitable zone, and that water delivery to these planets can potentially produce water content comparable to that of Earth. Our results broadly support the notion that habitable planets are plentiful around M dwarfs in the solar neighbourhood.

scholarly journals Characterization of M dwarfs using optical mid-resolution spectra for exploration of small exoplanets

2020 ◽  
Author(s):  
Yohei Koizumi ◽  
Masayuki Kuzuhara ◽  
Masashi Omiya ◽  
Teruyuki Hirano ◽  
John Wisniewski ◽  
...  
Keyword(s):  
Sample Selection ◽  
Optical Spectra ◽  
Average Error ◽  
Spectral Energy ◽  
M Dwarfs ◽  
Energy Distributions ◽  
Fitting Procedures ◽  
Optical Region ◽  
Selection For

Abstract We present the optical spectra of 338 nearby M dwarfs, and compute their spectral types, effective temperatures (Teff), and radii. Our spectra were obtained using several optical spectrometers with spectral resolutions that range from 1200 to 10000. As many as 97% of the observed M-type dwarfs have a spectral type of M3–M6, with a typical error of 0.4 subtype, among which the spectral types M4–M5 are the most common. We infer the Teff of our sample by fitting our spectra with theoretical spectra from the PHOENIX model. Our inferred Teff is calibrated with the optical spectra of M dwarfs whose Teff have been well determined with the calibrations that are supported by previous interferometric observations. Our fitting procedures utilize the VO absorption band (7320–7570 Å) and the optical region (5000–8000 Å), yielding typical errors of 128 K (VO band) and 85 K (optical region). We also determine the radii of our sample from their spectral energy distributions. We find most of our sample stars have radii of <0.6 R⊙, with the average error being 3%. Our catalog enables efficient sample selection for exoplanet surveys around nearby M-type dwarfs.

scholarly journals A circular polarization survey for radio stars with the Australian SKA Pathfinder

2021 ◽  
Vol 502 (4) ◽  
pp. 5438-5454
Author(s):  
Joshua Pritchard ◽  
Tara Murphy ◽  
Andrew Zic ◽  
Christene Lynch ◽  
George Heald ◽  
...  
Keyword(s):  
Radio Emission ◽  
Brightness Temperature ◽  
Circular Polarization ◽  
Flux Density ◽  
Wide Band ◽  
M Dwarfs ◽  
Square Kilometre Array ◽  
Population Statistics ◽  
Chemically Peculiar ◽  
Radio Stars

ABSTRACT We present results from a circular polarization survey for radio stars in the Rapid ASKAP Continuum Survey (RACS). RACS is a survey of the entire sky south of δ = +41○ being conducted with the Australian Square Kilometre Array Pathfinder telescope (ASKAP) over a 288 MHz wide band centred on 887.5 MHz. The data we analyse include Stokes I and V polarization products to an RMS sensitivity of 250 μJy PSF−1. We searched RACS for sources with fractional circular polarization above 6 per cent, and after excluding imaging artefacts, polarization leakage, and known pulsars we identified radio emission coincident with 33 known stars. These range from M-dwarfs through to magnetic, chemically peculiar A- and B-type stars. Some of these are well-known radio stars such as YZ CMi and CU Vir, but 23 have no previous radio detections. We report the flux density and derived brightness temperature of these detections and discuss the nature of the radio emission. We also discuss the implications of our results for the population statistics of radio stars in the context of future ASKAP and Square Kilometre Array surveys.

scholarly journals The Solar Neighborhood. XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc

2019 ◽  
Vol 157 (6) ◽  
pp. 216 ◽  
Author(s):  
Jennifer G. Winters ◽  
Todd J. Henry ◽  
Wei-Chun Jao ◽  
John P. Subasavage ◽  
Joseph P. Chatelain ◽  
...  
Keyword(s):  
Solar Neighborhood ◽  
M Dwarfs

scholarly journals Earth-size planet formation in the habitable zone of circumbinary stars

2020 ◽  
Vol 494 (1) ◽  
pp. 1045-1057 ◽  
Author(s):  
G O Barbosa ◽  
O C Winter ◽  
A Amarante ◽  
A Izidoro ◽  
R C Domingos ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Planet Formation ◽  
Terrestrial Planet ◽  
Close Binary ◽  
Habitable Zone ◽  
Density Profiles ◽  
Habitable Planets ◽  
Habitable Zones ◽  
Test Particles ◽  
The Stability

ABSTRACT This work investigates the possibility of close binary (CB) star systems having Earth-size planets within their habitable zones (HZs). First, we selected all known CB systems with confirmed planets (totaling 22 systems) to calculate the boundaries of their respective HZs. However, only eight systems had all the data necessary for the computation of HZ. Then, we numerically explored the stability within HZs for each one of the eight systems using test particles. From the results, we selected five systems that have stable regions inside HZs, namely Kepler-34,35,38,413, and 453. For these five cases of systems with stable regions in HZ, we perform a series of numerical simulations for planet formation considering discs composed of planetary embryos and planetesimals, with two distinct density profiles, in addition to the stars and host planets of each system. We found that in the case of the Kepler-34 and 453 systems, no Earth-size planet is formed within HZs. Although planets with Earth-like masses were formed in Kepler-453, they were outside HZ. In contrast, for the Kepler-35 and 38 systems, the results showed that potentially habitable planets are formed in all simulations. In the case of the Kepler-413system, in just one simulation, a terrestrial planet was formed within HZ.

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