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Re: Is Mercury a Former Gas Giant?
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Re: Is Mercury a Former Gas Giant? Jacob Krolo 05-14-2008
Posted by Jacob Krolo on May 14, 2008, 12:00 pm
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> What happens to a gas giant in a protosolar dust disc, if it's in as
> close an orbit as Mercury when stellar radiation reaches different
> levels?
>
> Could the shockwave of radiation actually remove a gas giant's
> atmosphere -- if it were close enough to the emerging sun -- leaving
> behind the core?

----------------------------------------------------------------------------
------------------------

Obviously, Mercury is tidally locked to the Sun, but, if we would like to
speculate about its previous life we

should re-examined our views about, so-called "established theories of
planetary evolution".

Before the discovery of the 51 Pegasi b, a Jupiter-class planet (0.468 Mass
of Jupiter) which

was confirmed in 1995., it was entrenched theory (created on one example) of
planetary evolution allowing to

giant planets to form at distances greater than several AU from the parent
star. That's meaning, narrow-minded

perceptions presumed, at about the distance of Jupiter from the sun.

51 Pegasi b orbits its host star in just 4.23 days (which is only 4.8
percent of the period of 88 days, what Mercury

need to complete a trip around the Sun) at distance of 0.05 AU, (7.5
million kilometres, 4.687 million miles), which

is much closer than Mercury orbits our Sun (12.8 percent Mercury's distance
in his elliptical orbit of 47 million km to

70 million km from the Sun).

That discovery was the proof that astronomical community at the time, didn't
have a slightest idea (regarding

planetary evolution) what's really going on over there.

At least that forced them to re-examine their theories J

How is possible to planet of this size could finished at this proximity to
the parent star?

Is it formed at its present position or in the outer regions of the system
and then interacted with a second giant planet

and migrated to its current position. Who knows? Your guess is good as
anybody else's and you are entitled to

come-up with your own "plausible" theory like some posters did in previous
treads.

However, in comparison to planet Mercury, 51 Pegasi b is much closer to its
parent star and

its thick atmosphere is not blown away by the solar wind, only because of
the gravitational force of the gas.

If Mercury ever had a "sufficiently massive atmosphere" it would be much
easier to retain it.

Obviously, that would be valid if Sun is constant as it is at it's present
stage. In later evolutionary stages, in next few

billion years, when Sun runs out of hydrogen fuel, will swell into its 'red
giant' stage. It's easy to imagine that in the

process of expansion would incinerate, not only Mercury and its presumed
"sufficiently massive atmosphere", but

the rest of the inner rocky planets.



Jacob



Posted by windbag on May 14, 2008, 3:02 pm
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 The age of 51 pegasi could be an issue.

Posted by Jacob Krolo on May 15, 2008, 7:50 am
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> The age of 51 pegasi could be an issue.
----------------------------------------------------------------------------
--------------------

Applying the "Theory of stellar structure and evolution", scientists
(astronomers) have been
able to calculate that the Sun is 4.5 billion years old, which is close to
the figure of 4.6 billion
years, for the rest of the solar system.
Using the same "Theory of stellar structure and evolution", astronomers
calculated that the
51 Pegasi (yellow dwarf star) is older (7.5 billion years) than the Sun.
What is most important for us in order to try to find the answer on
question, how is possible
for gas giant 51 Pegasi b, like Mercury tidally locked and so close to its
parent star, to retain
the atmosphere without having been stripped away.
I mentioned already that gravitational forces of the gas, actually prevented
atmosphere not to
be blown away.
Surprisingly, recent calculations after planetary atmospheres temperature
measurements, indi-
cated that planet under such a conditions, could hold to its Hydrogen/Helium
atmosphere
over the period of the lifetime of its parent star. In the same period,
loosing only about 5%
of its atmosphere.
Once again, if Mercury ever had a "sufficiently massive atmosphere", I'm of
opinion that it
would be possible holding it to the present time.

Jacob








Posted by windbag on May 15, 2008, 3:43 pm
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Shouldn't a certain amount of any planet's volatile gasses be stripped
away in a solar system, regardless of proximity, star age or type?



Jacob Krolo wrote:
> > The age of 51 pegasi could be an issue.
> ----------------------------------------------------------------------------
> --------------------
>
> Applying the "Theory of stellar structure and evolution", scientists
> (astronomers) have been
> able to calculate that the Sun is 4.5 billion years old, which is close to
> the figure of 4.6 billion
> years, for the rest of the solar system.
> Using the same "Theory of stellar structure and evolution", astronomers
> calculated that the
> 51 Pegasi (yellow dwarf star) is older (7.5 billion years) than the Sun.
> What is most important for us in order to try to find the answer on
> question, how is possible
> for gas giant 51 Pegasi b, like Mercury tidally locked and so close to its
> parent star, to retain
> the atmosphere without having been stripped away.
> I mentioned already that gravitational forces of the gas, actually prevented
> atmosphere not to
> be blown away.
> Surprisingly, recent calculations after planetary atmospheres temperature
> measurements, indi-
> cated that planet under such a conditions, could hold to its Hydrogen/Helium
> atmosphere
> over the period of the lifetime of its parent star. In the same period,
> loosing only about 5%
> of its atmosphere.
> Once again, if Mercury ever had a "sufficiently massive atmosphere", I'm of
> opinion that it
> would be possible holding it to the present time.
>
> Jacob

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