M Dwarfs: The Search for Life is On

Astrobiology Magazine article - M Dwarfs: The Search for Life is On -
Interview with Todd Henry

The link:
http://www.astrobio.net/news/modules...cle&sid= 1694

(Their) Summary (Aug 29, 2005): M-dwarf stars, much smaller, dimmer and
cooler than stars like our sun, are by far the most common type of star
in our galaxy. Yet scientists searching for life on other worlds have
not shown much interest in M dwarfs. That's about to change.
__________________________
The interview reveals a scientists fear of hypotheses being wrecked and
gives an insiders view of the main objections to M Dwarf habitability
and how they can be surmounted. The interesting point to me was that
if one adds up the habitable zone volumes around M Dwarf stars they
equal the amount of habitable zone volume of G Dwarfs (sun-like stars).

Search! Jason H.

Jason H. wrote:
Astrobiology Magazine article - M Dwarfs: The Search for Life is On -
Interview with Todd Henry

The link:
http://www.astrobio.net/news/modules...cle&sid= 1694

(Their) Summary (Aug 29, 2005): M-dwarf stars, much smaller, dimmer and
cooler than stars like our sun, are by far the most common type of star
in our galaxy. Yet scientists searching for life on other worlds have
not shown much interest in M dwarfs. That's about to change.

Great! I knew M Dwarfs were cool! (so to speak) :-)

__________________________
The interview reveals a scientists fear of hypotheses being wrecked and
gives an insiders view of the main objections to M Dwarf habitability
and how they can be surmounted. The interesting point to me was that
if one adds up the habitable zone volumes around M Dwarf stars they
equal the amount of habitable zone volume of G Dwarfs (sun-like stars).

Search! Jason H.

hello alfred
I dont think scientists will find sentiant life in our life time.

brains wrote:
hello alfred
I dont think scientists will find sentiant life in our life time.


Well, that may be so. However, "never give up, never surrender" :-) for
surely if we do then we won't ...

I'm hoping that scientists will find the first Earth-like planets before
I'm dust though :-)
Al

Wasn't it Jason H. who wrote:
The interesting point to me was that
if one adds up the habitable zone volumes around M Dwarf stars they
equal the amount of habitable zone volume of G Dwarfs (sun-like stars).

Although the total volume of M Dwarf habitable zone might be quite
large, each one of those zones is rather narrow. This means that a
relatively small change in the luminosity of the star, or the orbit of
the planet can cause it to move out of the habitable zone and all the
simple life forms get roasted or frozen before they can evolve info
complex organisms.

--
Mike Williams
Gentleman of Leisure

Mike Williams wrote:
Wasn't it Jason H. who wrote:

The interesting point to me was that
if one adds up the habitable zone volumes around M Dwarf stars they
equal the amount of habitable zone volume of G Dwarfs (sun-like stars).


Although the total volume of M Dwarf habitable zone might be quite
large, each one of those zones is rather narrow. This means that a
relatively small change in the luminosity of the star, or the orbit of
the planet can cause it to move out of the habitable zone and all the
simple life forms get roasted or frozen before they can evolve info
complex organisms.

However, this effect will not be so drastic (roasting or frozen) if the
planet has an atmosphere.

We need to keep in mind that simple lifeforms on Earth seem to survive
in the most incredible environments. This we know, and it may be
therefore that we'll find simple lifeforms on comets, Mars, Europa,
Titan, ..., etc. There is no reason, at least at this time, to eliminate
the M Dwarf stars ... The idea of "habitable zone" may not be so
stringent for life as once thought ...

You know how these "hot Jupiter" large planets have been found orbiting
near to their stars, well the same could happen with the M Dwarfs except
the planets would be Earth sized and small (not the giant planet
recently found around G type stars). M Dwarfs could have scores of small
Earth sized planets orbiting close to their stars. M Dwarfs could be ,
after all, a zoo for lifeforms ...

Al

In message , Mike Williams
writes
Wasn't it Jason H. who wrote:
The interesting point to me was that
if one adds up the habitable zone volumes around M Dwarf stars they
equal the amount of habitable zone volume of G Dwarfs (sun-like stars).

Although the total volume of M Dwarf habitable zone might be quite
large, each one of those zones is rather narrow. This means that a
relatively small change in the luminosity of the star, or the orbit of
the planet can cause it to move out of the habitable zone and all the
simple life forms get roasted or frozen before they can evolve info
complex organisms.

But how likely is that? The whole point about M dwarfs is that they are
supposedly stable for tens (hundreds ?) of billions of years. They do
have a problem with short-term stability as they often have very large
solar flares, but I've seen arguments saying that isn't necessarily
fatal.
"Proxima's Planet" sounds quite possible - as I've said before, I'm
looking at a print as I type.
--
Remove spam and invalid from address to reply.

Jonathan Silverlight wrote:
In message , Mike Williams
writes

Wasn't it Jason H. who wrote:

The interesting point to me was that
if one adds up the habitable zone volumes around M Dwarf stars they
equal the amount of habitable zone volume of G Dwarfs (sun-like stars).


Although the total volume of M Dwarf habitable zone might be quite
large, each one of those zones is rather narrow. This means that a
relatively small change in the luminosity of the star, or the orbit of
the planet can cause it to move out of the habitable zone and all the
simple life forms get roasted or frozen before they can evolve info
complex organisms.

But how likely is that? The whole point about M dwarfs is that they are
supposedly stable for tens (hundreds ?) of billions of years. They do
have a problem with short-term stability as they often have very large
solar flares, but I've seen arguments saying that isn't necessarily fatal.
"Proxima's Planet" sounds quite possible - as I've said before, I'm
looking at a print as I type.

The flares are a result of the rapid rotation of a young M Dwarf ... the
flares die off as the rotation rate decreases (the flares themselves are
responsible for slowing down the rotation rate). I'm not sure how long
it takes for the flare activity to decrease to "acceptable" levels but
the article indicated a billion years or so which is nothing in the
possible lifetime of an M Dwarf (up to trillions of years) ...

In message , Alfred A.
Aburto Jr. writes
Jonathan Silverlight wrote:
In message , Mike Williams
writes

Although the total volume of M Dwarf habitable zone might be quite
large, each one of those zones is rather narrow. This means that a
relatively small change in the luminosity of the star, or the orbit of
the planet can cause it to move out of the habitable zone and all the
simple life forms get roasted or frozen before they can evolve info
complex organisms.

But how likely is that? The whole point about M dwarfs is that they
are supposedly stable for tens (hundreds ?) of billions of years. They
have a problem with short-term stability as they often have very large
solar flares, but I've seen arguments saying that isn't necessarily
fatal.
"Proxima's Planet" sounds quite possible - as I've said before, I'm
looking at a print as I type.

The flares are a result of the rapid rotation of a young M Dwarf ...
the flares die off as the rotation rate decreases (the flares
themselves are responsible for slowing down the rotation rate). I'm not
sure how long it takes for the flare activity to decrease to
"acceptable" levels but the article indicated a billion years or so
which is nothing in the possible lifetime of an M Dwarf (up to
trillions of years) ...

Thanks - I didn't know that. But where's the angular momentum going?
AIUI, in the case of stars like the Sun it's transferred to the
protoplanetary disk, which is why fast-spinning stars like Altair
probably don't have planets.

Corrections welcomed, as usual, and in searching for some on-line info I
found this gem http://www.talkorigins.org/indexcc/CE/CE302.html
"The sun has 99 percent of the mass of the solar system, but less than 1
percent of the angular momentum. It is spinning too slowly to have
formed naturally.
Source:
Brown, Walt, 1995. In the Beginning: Compelling evidence for creation
and the Flood. Phoenix, AZ: Center for Scientific Creation, p. 19."

Jonathan Silverlight wrote:
In message , Alfred A.
Aburto Jr. writes

Jonathan Silverlight wrote:
In message , Mike Williams
writes


Although the total volume of M Dwarf habitable zone might be quite
large, each one of those zones is rather narrow. This means that a
relatively small change in the luminosity of the star, or the orbit of
the planet can cause it to move out of the habitable zone and all the
simple life forms get roasted or frozen before they can evolve info
complex organisms.

But how likely is that? The whole point about M dwarfs is that they
are supposedly stable for tens (hundreds ?) of billions of years.
They have a problem with short-term stability as they often have very
large solar flares, but I've seen arguments saying that isn't
necessarily fatal.
"Proxima's Planet" sounds quite possible - as I've said before, I'm
looking at a print as I type.


The flares are a result of the rapid rotation of a young M Dwarf ...
the flares die off as the rotation rate decreases (the flares
themselves are responsible for slowing down the rotation rate). I'm
not sure how long it takes for the flare activity to decrease to
"acceptable" levels but the article indicated a billion years or so
which is nothing in the possible lifetime of an M Dwarf (up to
trillions of years) ...


Thanks - I didn't know that. But where's the angular momentum going?

The angular momentum from the star is transferred to its far flung
magnetic field ... which can disappear, can be shed, into space and be
lost... I read this somewhere in learning more about flare stars, but I
will remember to look for a reference regarding this ...

AIUI, in the case of stars like the Sun it's transferred to the
protoplanetary disk, which is why fast-spinning stars like Altair
probably don't have planets.

We are not sure about Altair or other rapidly rotating stars. I thought
Altair might be a flare star too, but oddly it doesn't seem to be.

I wondered about this too (angular momentum being transferred to the
protoplanetary disk), but like the rest of the star types not all of M
Dwarfs may be fast rotators ... I'm not sure that all M Dwarfs are flare
stars (fast rotators) ... a good text on M Dwarfs is needed that is for
sure ...

Well, I know that in the stellar formation models that M Dwarfs do form
protoplanetary disks. Also I seem to remember recently that a M Dwarf
was found to have a protoplanetary disk ...

Anyway, lots to think about regarding M Dwarfs and planets and life ...


Corrections welcomed, as usual, and in searching for some on-line info I

I prefer to think of "learning" instead of "corrections" :-)

found this gem http://www.talkorigins.org/indexcc/CE/CE302.html
"The sun has 99 percent of the mass of the solar system, but less than 1
percent of the angular momentum. It is spinning too slowly to have
formed naturally.
Source:
Brown, Walt, 1995. In the Beginning: Compelling evidence for creation
and the Flood. Phoenix, AZ: Center for Scientific Creation, p. 19."

Wow! It frightens me to think that people teach their children these
un-truths. Might as well say it! They are lies.