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Stellar encounters with giant molecular clouds

Kokaia, Giorgi LU and Davies, Melvyn B. LU (2019) In Monthly Notices of the Royal Astronomical Society 489(4). p.5165-5180
Abstract

Giant molecular clouds (GMCs) are believed to affect the biospheres of planets as their host star passes through them. We simulate the trajectories of stars and GMCs in the Galaxy and determine how often stars pass through GMCs. We find a strong decreasing dependence with Galactocentric radius, and with the velocity perpendicular to the Galactic plane, Vz. The XY-component of the kinematic heating of stars was shown to not affect the GMC hit rate, unlike the Z-dependence (Vz) implies that stars hit fewer GMCs as they age. GMCs are locations of star formation, therefore we also determine how often stars pass near supernovae. For the supernovae the decrease with Vz is steeper as how fast the star passes... (More)

Giant molecular clouds (GMCs) are believed to affect the biospheres of planets as their host star passes through them. We simulate the trajectories of stars and GMCs in the Galaxy and determine how often stars pass through GMCs. We find a strong decreasing dependence with Galactocentric radius, and with the velocity perpendicular to the Galactic plane, Vz. The XY-component of the kinematic heating of stars was shown to not affect the GMC hit rate, unlike the Z-dependence (Vz) implies that stars hit fewer GMCs as they age. GMCs are locations of star formation, therefore we also determine how often stars pass near supernovae. For the supernovae the decrease with Vz is steeper as how fast the star passes through the GMC determines the probability of a supernova encounter. We then integrate a set of Sun-like trajectories to see the implications for the Sun. We find that the Sun hits 1.6 ± 1.3 GMCs per Gyr which results in 1.5 ± 1.1 or (with correction for clustering) 0.8 ± 0.6 supernova closer than 10 pc per Gyr. The different the supernova frequencies are from whether one considers multiple supernovae per GMC crossing (few Myr) as separate events. We then discuss the effect of the GMC hits on the Oort cloud, and the Earth’s climate due to accretion, we also discuss the records of distant supernova. Finally, we determine Galactic Habitable Zone using our model. For the thin disc, we find it to lie between 5.8 and 8.7 kpc and for the thick disc to lie between 4.5 and 7.7 kpc.

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author
and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Astrobiology, ISM: clouds, Stars: general, Stars: kinematics and dynamics, Sun: general, Supernovae: general
in
Monthly Notices of the Royal Astronomical Society
volume
489
issue
4
pages
16 pages
publisher
Oxford University Press
external identifiers
  • scopus:85075257598
ISSN
1365-2966
DOI
10.1093/mnras/stz813
language
English
LU publication?
yes
id
44ec3f0d-99f9-4735-800a-fe0e82917025
date added to LUP
2019-12-09 09:45:02
date last changed
2024-02-16 03:56:47
@article{44ec3f0d-99f9-4735-800a-fe0e82917025,
  abstract     = {{<p>Giant molecular clouds (GMCs) are believed to affect the biospheres of planets as their host star passes through them. We simulate the trajectories of stars and GMCs in the Galaxy and determine how often stars pass through GMCs. We find a strong decreasing dependence with Galactocentric radius, and with the velocity perpendicular to the Galactic plane, V<sub>z</sub>. The XY-component of the kinematic heating of stars was shown to not affect the GMC hit rate, unlike the Z-dependence (V<sub>z</sub>) implies that stars hit fewer GMCs as they age. GMCs are locations of star formation, therefore we also determine how often stars pass near supernovae. For the supernovae the decrease with V<sub>z</sub> is steeper as how fast the star passes through the GMC determines the probability of a supernova encounter. We then integrate a set of Sun-like trajectories to see the implications for the Sun. We find that the Sun hits 1.6 ± 1.3 GMCs per Gyr which results in 1.5 ± 1.1 or (with correction for clustering) 0.8 ± 0.6 supernova closer than 10 pc per Gyr. The different the supernova frequencies are from whether one considers multiple supernovae per GMC crossing (few Myr) as separate events. We then discuss the effect of the GMC hits on the Oort cloud, and the Earth’s climate due to accretion, we also discuss the records of distant supernova. Finally, we determine Galactic Habitable Zone using our model. For the thin disc, we find it to lie between 5.8 and 8.7 kpc and for the thick disc to lie between 4.5 and 7.7 kpc.</p>}},
  author       = {{Kokaia, Giorgi and Davies, Melvyn B.}},
  issn         = {{1365-2966}},
  keywords     = {{Astrobiology; ISM: clouds; Stars: general; Stars: kinematics and dynamics; Sun: general; Supernovae: general}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{5165--5180}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{Stellar encounters with giant molecular clouds}},
  url          = {{http://dx.doi.org/10.1093/mnras/stz813}},
  doi          = {{10.1093/mnras/stz813}},
  volume       = {{489}},
  year         = {{2019}},
}