Gliese 436 c

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Gliese 436 c

Post by Stalker on 4th September 2010, 3:47 pm

A nice paper of Dr. Ballard has been accepted and for publication and should appear on astro-ph on Tue 7 Sep. Wink

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Re: Gliese 436 c

Post by Borislav on 4th September 2010, 4:16 pm

Wow! Finally. And where information? There will be a press conference by NASA?

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Re: Gliese 436 c

Post by tommi59 on 4th September 2010, 4:47 pm

This is super earth like 2 years ago??where did you get this information any link?? where i can read about it??
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Re: Gliese 436 c

Post by Sirius_Alpha on 4th September 2010, 4:54 pm

Says so on the EPOXI facebook page. Smile

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Re: Gliese 436 c

Post by Stalker on 4th September 2010, 5:09 pm


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Re: Gliese 436 c

Post by Borislav on 4th September 2010, 5:15 pm

Thank you for your answers. That means you, too, Stalker was born in Siberia. Smile I'm from Kemerovo.

In general the last few weeks are very rich in exoplanets. And the October - November, hope will publish many discoveries of Kepler.

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Re: Gliese 436 c

Post by Lazarus on 4th September 2010, 5:34 pm

Er, wow... so much for "super".
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Re: Gliese 436 c

Post by tommi59 on 4th September 2010, 5:51 pm

Hmm very interesting I am curious about mass this planet and distance from star.
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Re: Gliese 436 c

Post by Sirius_Alpha on 4th September 2010, 5:56 pm

"unter-Earth"

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Re: Gliese 436 c

Post by Borislav on 4th September 2010, 5:57 pm

I think this is the same candidate.

http://arxiv.org/abs/0909.2875
4.1. Best Candidate Transit Signal
We find no transit signals for GJ 436c at the significance limit set by 2=250. We present
our best candidate here, which corresponds to a planet with radius 1.04 R and period 8.42 days.
The improvement in the 2 over the null hypothesis is 170. We investigate the possibility of signal
suppression by masking these suspected transit points from the points used to create the 2D spline,
and recreating the spline surface. We find that the candidate transit depth is unaltered, indicating
that these points are well-sampled on the CCD. In Figure 8, we show the phased and binned best
candidate signal, as well as the two observed candidate transit events separately. The gap in the
middle of the first event is due to the star wandering off the bottom edge of the CCD for a period
of about an hour.

In general, a period of about 9 days.

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Re: Gliese 436 c

Post by Borislav on 4th September 2010, 6:14 pm

The most interesting question - it was to measure the mass? After the January observations Spitzer has been more than 6 months. It is a pity that in the Keck Observatory publish logs of observations, only with a lag of 18 months.
https://koa.ipac.caltech.edu/available_date.html

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Re: Gliese 436 c

Post by Sirius_Alpha on 4th September 2010, 6:19 pm

If transit timing variations can be positively detected, the mass can be measured through that.

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Re: Gliese 436 c

Post by Borislav on 4th September 2010, 6:28 pm

It is interesting that there were repeated observations of this star Spitzer.

http://ssc.spitzer.caltech.edu/warmmission/scheduling/observinglogs/plan/alltogether.txt
GJ436b-ecl-c 11:42:11.00 26:42:23.00 Harringt JH-ESP-T 60003 iracmapp 357.41 2010-06-23 17:42:27.0 38807296 GJ436b-ecl-ch1-1
GJ436b-ecl-c 11:42:16.85 26:42: 4.90 Harringt JH-ESP-T 60003 iracmapp 4.03 2010-06-23 23:36:32.7 38806016 GJ436b-ecl-ch1-1-co

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Re: Gliese 436 c

Post by Sirius_Alpha on 4th September 2010, 6:38 pm

Could be for additional, high-accuracy TTV measurements.

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Re: Gliese 436 c

Post by Borislav on 4th September 2010, 7:45 pm

In general, if you take these three observation windows GJ436:

1) 2010-01-28 06:54:44.0 - 2010-01-29 00:45:01.2

2) 2010-06-23 17:42:27.0 - 2010-06-23 23:36:32.7

3) 2010-06-29 00:55:18.3 - 2010-06-29 06:49:21.3

In the period of 8.42 days get 1 and 3 windows. Second windows out of calculations.

Please recheck.

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Re: Gliese 436 c

Post by Borislav on 4th September 2010, 7:58 pm

In addition to the 1 and 3 window Spitzer observed for 2 channel (4.5 micron), in 2 window - 1 channel (3.6 microns).

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Re: Gliese 436 c

Post by Sirius_Alpha on 4th September 2010, 8:09 pm

I think you're right. The first and third windows are ~18 orbital periods apart.

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Re: Gliese 436 c

Post by Edasich on 5th September 2010, 4:29 am

Uhm 0.75 Earth radii would quite beat both CoRoT and Kepler. Laughing Very Happy

Whan they state "Earth-like", I think they refer to composition rather orbital location. Anyway let's wait for Sep 7.
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Re: Gliese 436 c

Post by Sirius_Alpha on 5th September 2010, 8:11 am

If indeed it has a period of 8.42 d, the planet will get about 9 times the insolation that Earth does. Clearly too hot to be habitable.

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Re: Gliese 436 c

Post by tommi59 on 5th September 2010, 8:54 am

It is obvious habitable zone around gj 436 star is from 0.12 AU(high albedo) to 0.3AU(low albedo,dense atmosphere).Planet c Will be very hot.


Last edited by tommi59 on 5th September 2010, 9:56 am; edited 1 time in total
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Re: Gliese 436 c

Post by Lazarus on 5th September 2010, 9:52 am

As I understand it, the liquid water habitable zone around red dwarfs occurs for lower insolation values than for solar type stars because Rayleigh scattering is less efficient for longer wavelengths, plus there are various absorption features in the spectra of various atmospheric constituents. This results in a decrease in the albedo of the planet.
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Re: Gliese 436 c

Post by Edasich on 5th September 2010, 3:00 pm

Lazarus wrote:As I understand it, the liquid water habitable zone around red dwarfs occurs for lower insolation values than for solar type stars because Rayleigh scattering is less efficient for longer wavelengths, plus there are various absorption features in the spectra of various atmospheric constituents. This results in a decrease in the albedo of the planet.

Interesting point. But likely we may deal with a planet within equivalent orbital separation of Mercury.
Maybe something more like a "more-extreme-Venus"...a Phosphorian planet as in Dollan's ArcBuilder
Fantasy gets concrete Laughing
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Re: Gliese 436 c

Post by Borislav on 6th September 2010, 2:16 am

So, what should already be at least 5 observed transits - two EPOXI in the visible band, a Spitzer at 8 micron, and the two Spitzer observation at 4.5 microns.

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Re: Gliese 436 c

Post by Sirius_Alpha on 6th September 2010, 8:09 am

You know... it could be that the paper will say something like this.

"After using Spitzer 4.5 and 8 Ám photometry during the predicted transit times of the planet, we rule out additional transiting planets with radii > 0.75 RE with 3σ confidence. Furthermore, we find no evidence of transit timing variations for Gliese 436 b."

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Re: Gliese 436 c

Post by Borislav on 6th September 2010, 8:35 am

It is possible of course. This may explain why no press conference, NASA, and the only article in the Archiv.org.

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Re: Gliese 436 c

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