[ExI] Scientists Find Solar System Like Ours

The Avantguardian avantguardian2020 at yahoo.com
Fri Feb 15 22:12:22 UTC 2008

--- Amara Graps <amara at amara.com> wrote:

> What? You didn't like my Valentine's Day present?

I like it a lot. And Happy Belated Valentine to you, dear Amara.

> If you didn't notice.. try here:
> "Alien Planetary System Looks a Lot Like Home"
> http://www.sciencemag.org/cgi/content/full/319/5865/885
> Yeah, yeah, I know, you're thinking ...
> "250 extrasolar planets known ... now another one ... ho hum..."

Actually I am impressed. Most of the exoplanetary systems to date have
had "hot jupiters" casting their huge shadows into the life zone.
> OK, I'll tell you why this discovery: "OGLE-2006-BLG-109"
> (to be precise: "OGLE-2006-BLG-10Lb" and "OGLE-2006-BLG-109Lc")
> is so cool:
> 1) It represents a SCALED version of our solar system with a
> less-massive host star.
> It found planets of mass:
> 	2/3 M_jupiter AND 1/2 M_saturn orbiting at distances of
> 	about 2.3 and 4.6 AU
> 	(in our own solar system we have M_jupiter and M_saturn
> 	orbiting at distances of 5 and 10 AU)

Given my amateur inquiry into the "Titus-Bode" scaling/orbital
resonance of our solar system, this is an interesting coincidence, no? 

> - Equilibrium temperatures of T ~82K and T ~59 K
> 	(30% less than Jupiter and Saturn)
> - Orbiting around a reddish star of mass 1/2 M_sun
> 2) It was found by MICROLENSING, not by Doppler methods. This means
> that [1]
> - one doesn't need to wait for the planet to complete an orbit
> - lensing zone is typically between 1.5 - 6 AU (AU = distance: Earth
> to Sun)
> - sensitive (i.e. large signal to noise) to _low mass_ planets
> - can pick up the photometry in relatively small-aperture telescopes
> (even one's backyard 10 inch 'scopes)

It does seem to me that this method could be used to search for other
garden planets ie. earth-like. One would merely have to restrict the
search to those stars of a spectral class that would put their life
zone in the 1.5 - 6 AU range. Perhaps SETI should be coordinating with
these exo-planet people by following up their discoveries with targeted
eavesdropping rather than just doing whole sky sweeps.  

> _These planets could _not_ have been detected by the Doppler
> technique_

I am curious, could microlensing be performed with a galaxy aligned in
the background instead of another star? Seems to me that that would
greatly increase the technique's usefulness. 

Any case. *SMOOCH* Thanks for the present. ;-)

Stuart LaForge
alt email: stuart"AT"ucla.edu

"Life is the sum of all your choices."  
Albert Camus

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