Science Fiction
Dictionary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 |
Our Galaxy's Habitable Zone
Where are the habitable planets in our galaxy and how numerous are they during the course of the galaxy's life? A new paper by researchers Michael G. Gowanlock, David R. Patton and Sabine M. McConnell seeks to provide answers to these questions.
We present a model of the Galactic Habitable Zone (GHZ), described in terms of
the spatial and temporal dimensions of the Galaxy that may favour the development
of complex life. The Milky Way galaxy is modelled using a computational approach
by populating stars and their planetary systems on an individual basis using MonteCarlo methods. We begin with well-established properties of the disk of the Milky
Way, such as the stellar number density distribution, the initial mass function, the
star formation history, and the metallicity gradient as a function of radial position and
time. We vary some of these properties, creating four models to test the sensitivity
of our assumptions. To assess habitability on the Galactic scale, we model supernova
rates, planet formation, and the time required for complex life to evolve. Our study
improves on other literature on the GHZ by populating stars on an individual basis and
by modelling SNII and SNIa sterilizations by selecting their progenitors from within
this preexisting stellar population. Furthermore, we consider habitability on tidally
locked and non-tidally locked planets separately, and study habitability as a function
of height above and below the Galactic midplane. In the model that most accurately
reproduces the properties of the Galaxy, the results indicate that an individual SNIa
is ∼5.6× more lethal than an individual SNII on average. In addition, we predict that
∼1.2% of all stars host a planet that may have been capable of supporting complex
life at some point in the history of the Galaxy. Of those stars with a habitable planet,
∼75% of planets are predicted to be in a tidally locked configuration with their host
star. The majority of these planets that may support complex life are found towards
the inner Galaxy, distributed within, and significantly above and below, the Galactic
midplane.
(Habitable planets [pdf])
In this Figure, Model 1 is plotted. Top Left panel: The number of planets that are habitable (tidally-locked and non-locked) as a function of radial distance and time. We trace the history of each habitable planet to determine in which periods they remain habitable. It is clear, given the assumptions made in our model, that the number of habitable planets is greatest in the inner Galaxy, at all epochs. Top right panel: The fraction of stars with a habitable planet as a function of time and radial distance. We trace the history of each habitable planet to determine in which periods they remain habitable. Given the assumptions made in the model, the inner region of the Galaxy exhibits the highest probability of having habitable planets at the present day. At R∼5-11 kpc, at the present day, the entire range has roughly the same probability of having habitable planets. Lower Left panel: The number of habitable planets integrated over all epochs as a function of radial distance and height above the midplane. We predict that the position in the Galaxy with the greatest number of habitable planets is located in and around the midplane in the inner Galaxy. Lower Right panel: The fraction of habitable planets integrated over all epochs as a function of radial distance and height above the midplane. The region with the greatest fraction of habitable planets exists above the midplane in the inner Galaxy. The high metallicity that produces a high planet formation rate and the lower stellar density that exists well above the midplane at this radial position permits a greater fraction of habitable planets to form.
When I read about this kind of research, I think about the science fiction authors who expanded our ideas about life in the galaxy, like E.E. 'Doc' Smith and Isaac Asimov. Your favorites?
From A Model of Habitability Within the Milky Way Galaxy by Michael G. Gowanlock, David R. Patton and Sabine M. McConnell.
Scroll down for more stories in the same category. (Story submitted 7/15/2011)
Follow this kind of news @Technovelgy.| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
Would
you like to contribute a story tip?
It's easy:
Get the URL of the story, and the related sf author, and add
it here.
Comment/Join discussion ( 1 )
Related News Stories - (" Space Tech ")
The New Habitable Zones Include Asimov's Ribbon Worlds
'...there's a narrow belt where the climate is moderate.' - Harl Vincent, 1931.
Will Space Stations Have Large Interior Spaces Again?
'They filed clumsily into the battleroom, like children in a swimming pool for the first time, clinging to the handholds along the side.' - Orson Scott Card, 1985.
Reflect Orbital Offers 'Sunlight on Demand' And Light Pollution
'I don't have to tell you about the seven two-mile-diameter orbital mirrors...'
Chrysalis Generation Ship to Alpha Centauri
'This was their world, their planet —
this swift-traveling, yet seemingly moveless vessel.' - Nat Schachner, 1934
Technovelgy (that's tech-novel-gee!) is devoted to the creative science inventions and ideas of sf authors. Look for the Invention Category that interests you, the Glossary, the Invention Timeline, or see what's New.
Science Fiction
Timeline
1600-1899
1900-1939
1940's 1950's
1960's 1970's
1980's 1990's
2000's 2010's
Current News
The New Habitable Zones Include Asimov's Ribbon Worlds
'...there's a narrow belt where the climate is moderate.'
Atlas Robot Makes Uncomfortable Movements
'Not like me. A T-1000, advanced prototype. A mimetic poly-alloy. Liquid metal.'
Boring Company Drills Asimov's Single Vehicle Tunnels
'It was riddled with holes that were the mouths of tunnels.'
Humanoid Robots Tickle The Ivories
'The massive feet working the pedals, arms and hands flashing and glinting...'
A Remarkable Coincidence
'There is a philosophical problem of some difficulty here...'
Cortex 1 - Today A Warehouse, Tomorrow A Calculator Planet
'There were cubic miles of it, and it glistened like a silvery Christmas tree...'
Perching Ambush Drones
'On the chest of drawers something was perched.'
Leader-Follower Autonomous Vehicle Technology
'Jason had been guiding the caravan of cars as usual...'
Golf Ball Test Robot Wears Them Out
"The robot solemnly hit a ball against the wall, picked it up and teed it, hit it again, over and again...'
Boring Company Vegas Loop Like Asimov Said
'There was a wall ahead... It was riddled with holes that were the mouths of tunnels.'
Rigid Metallic Clothing From Science Fiction To You
'...support the interior human structure against Jupiter’s pull.'
Is The Seattle Ultrasonics C-200 A Heinlein Vibroblade?
'It ain't a vibroblade. It's steel. Messy.'
Roborock Saros Z70 Is A Robot Vacuum With An Arm
'Anything larger than a BB shot it picked up and placed in a tray...'
A Beautiful Visualization Of Compact Food
'The German chemists have discovered how to supply the needed elements in compact, undiluted form...'
Bone-Building Drug Evenity Approved
'Compounds devised by the biochemists for the rapid building of bone...'
Secret Kill Switch Found In Yutong Buses
'The car faltered as the external command came to brake...'
