Astrobiological effects of F, G, K and M main-sequence stars

AbstractWe focus on the astrobiological effects of photospheric radiation produced by main-sequence stars of spectral types F, G, K, and M. The photospheric radiation is represented by using realistic spectra, taking into account millions or hundred of millions of lines for atoms and molecules. DNA is taken as a proxy for carbon-based macromolecules, assumed to be the chemical centerpiece of extraterrestrial life forms. Emphasis is placed on the investigation of the radiative environment in conservative as well as generalized habitable zones.

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The evolution of habitable zones during stellar lifetimes and its implications on the search for extraterrestrial life

International Journal of Astrobiology ◽

10.1017/s1473550404001715 ◽

2003 ◽

Vol 2 (4) ◽

pp. 289-299 ◽

Cited By ~ 61

Author(s):

D.R. Underwood ◽

B.W. Jones ◽

P.N. Sleep

Keyword(s):

Main Sequence ◽

Giant Planet ◽

Giant Planets ◽

Main Sequence Stars ◽

Extraterrestrial Life ◽

The Past ◽

Habitable Zones ◽

Gravitational Influence ◽

Stellar Masses ◽

Do So

A stellar evolution computer model has been used to determine changes in the luminosity L and effective temperature Te of single stars during their time on the main sequence. The range of stellar masses investigated was from 0.5 to 1.5 times that of the Sun, each with a mass fraction of metals (metallicity, Z) from 0.008 to 0.05. The extent of each star's habitable zone (HZ) has been determined from its values of L and Te. These stars form a reference framework for other main sequence stars. All of the 104 main sequence stars known to have one or more giant planets have been matched to their nearest stellar counterpart in the framework, in terms of mass and metallicity, hence closely approximating their HZ limits. The limits of HZ, for each of these stars, have been compared to their giant planet(s)'s range of strong gravitational influence. This allows a quick assessment as to whether Earth-mass planets could exist in stable orbits within the HZ of such systems, both presently and at any time during the star's main sequence lifetime. A determination can also be made as to the possible existence of life-bearing satellites of giant planets, which orbit within HZs. Results show that about half of the 104 known extrasolar planetary systems could possibly have been housing an Earth-mass planet in HZs during at least the past billion years, and about three-quarters of the 104 could do so for at least a billion years at some time during their main sequence lives. Whether such Earth-mass planets could have formed is an urgent question now being investigated by others, with encouraging results.

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Biological damage due to photospheric, chromospheric and flare radiation in the environments of main-sequence stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309993036 ◽

2009 ◽

Vol 5 (S264) ◽

pp. 419-426 ◽

Cited By ~ 1

Author(s):

Manfred Cuntz ◽

Edward F. Guinan ◽

Robert L. Kurucz

Keyword(s):

Main Sequence ◽

Life Forms ◽

Flare Activity ◽

Atmospheric Attenuation ◽

Main Sequence Stars ◽

Extraterrestrial Life ◽

Biological Damage ◽

Statistical Sense ◽

Stellar Magnetic Fields ◽

Synthetic Models

AbstractWe explore the biological damage initiated in the environments of F, G, K, and M-type main-sequence stars due to photospheric, chromospheric and flare radiation. The amount of chromospheric radiation is, in a statistical sense, directly coupled to the stellar age as well as the presence of significant stellar magnetic fields and dynamo activity. With respect to photospheric radiation, we also consider detailed synthetic models, taking into account millions or hundred of millions of lines for atoms and molecules. Chromospheric UV radiation is increased in young stars in regard to all stellar spectral types. Flare activity is most pronounced in K and M-type stars, which also has the potential of stripping the planetary atmospheres of close-in planets, including planets located in the stellar habitable zone. For our studies, we take DNA as a proxy for carbon-based macromolecules, guided by the paradigm that carbon might constitute the biochemical centerpiece of extraterrestrial life forms. Planetary atmospheric attenuation is considered in an approximate manner.

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HABITABLE ZONES OF POST-MAIN SEQUENCE STARS

The Astrophysical Journal ◽

10.3847/0004-637x/823/1/6 ◽

2016 ◽

Vol 823 (1) ◽

pp. 6 ◽

Cited By ~ 25

Author(s):

Ramses M. Ramirez ◽

Lisa Kaltenegger

Keyword(s):

Main Sequence ◽

Main Sequence Stars ◽

Habitable Zones

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Habitable Zones around Main Sequence Stars

Icarus ◽

10.1006/icar.1993.1010 ◽

1993 ◽

Vol 101 (1) ◽

pp. 108-128 ◽

Cited By ~ 1377

Author(s):

James F. Kasting ◽

Daniel P. Whitmire ◽

Ray T. Reynolds

Keyword(s):

Main Sequence ◽

Main Sequence Stars ◽

Habitable Zones

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Habitable zones about main sequence stars

Icarus ◽

10.1016/0019-1035(79)90141-6 ◽

1979 ◽

Vol 37 (1) ◽

pp. 351-357 ◽

Cited By ~ 170

Author(s):

Michael H. Hart

Keyword(s):

Main Sequence ◽

Main Sequence Stars ◽

Habitable Zones

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Can Self-Replicating Species Flourish in the Interior of a Star?

10.31219/osf.io/j6gux ◽

2020 ◽

Author(s):

Luis Anchordoqui ◽

Eugene M. Chudnovsky

Keyword(s):

Low Temperature ◽

Nucleic Acids ◽

Main Sequence ◽

Main Sequence Stars ◽

Atoms And Molecules ◽

Form Of Life ◽

Advanced Form ◽

Life On Earth

The existing view of biological life is that it evolves under suitable conditions in the low-temperature world of atoms and molecules on the surface of a planet. It is believed that any plausible extraterrestrial form of life must resemble the life on Earth that is ruled by biochemistry of nucleic acids, proteins, and sugars. Going against this dogma, we argue that an advanced form of life based upon short-lived species can exist inside main-sequence stars like our Sun.

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ERRATUM: “HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES” (2013, ApJ, 765, 131)

The Astrophysical Journal ◽

10.1088/0004-637x/770/1/82 ◽

2013 ◽

Vol 770 (1) ◽

pp. 82 ◽

Cited By ~ 59

Author(s):

Ravi Kumar Kopparapu ◽

Ramses Ramirez ◽

James F. Kasting ◽

Vincent Eymet ◽

Tyler D. Robinson ◽

...

Keyword(s):

Main Sequence ◽

Main Sequence Stars ◽

Habitable Zones

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Dynamics and Habitability in Binary Star Systems

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314007820 ◽

2014 ◽

Vol 9 (S310) ◽

pp. 53-57

Author(s):

Siegfried Eggl ◽

Nikolaos Georgakarakos ◽

Elke Pilat-Lohinger

Keyword(s):

Main Sequence ◽

Binary Star ◽

Atmospheric Models ◽

Main Sequence Stars ◽

Habitable Zones ◽

Planetary Orbits ◽

Consistent Manner ◽

Earth Like Planets ◽

Complex Matter ◽

Planetary Habitability

AbstractDetermining planetary habitability is a complex matter, as the interplay between a planet's physical and atmospheric properties with stellar insolation has to be studied in a self consistent manner. Standardized atmospheric models for Earth-like planets exist and are commonly accepted as a reference for estimates of Habitable Zones. In order to define Habitable Zone boundaries, circular orbital configurations around main sequence stars are generally assumed. In gravitationally interacting multibody systems, such as double stars, however, planetary orbits are forcibly becoming non circular with time. Especially in binary star systems even relatively small changes in a planet's orbit can have a large impact on habitability. Hence, we argue that a minimum model for calculating Habitable Zones in binary star systems has to include dynamical interactions.

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