Kepler Mission Options

[Greg Hullender]

Since brightness of a star goes up as the fourth power of mass, it occurs to me that another problem presents itself: if a giant star did have a planet orbiting in the Goldilocks zone, that planet would have a period of decades or even centuries. There's simply no hope of seeing repeated transits.

--Greg

[Hungry4info]

Indeed. Another thing to consider is that even if this planet is in the habitable zone, it hasn't been for long, and won't be much longer. Habitable Earth-like planets around giant stars seem unlikely.

[Greg Hullender]

The official objectives for Kepler aren't limited just to potentially habitable planets:

Kepler Mission Scientific Objective:
The scientific objective of the Kepler Mission is to explore the structure and diversity of planetary systems. This is achieved by surveying a large sample of stars to:

1. Determine the percentage of terrestrial and larger planets there are in or near the habitable zone of a wide variety of stars;
2. Determine the distribution of sizes and shapes of the orbits of these planets;
3. Estimate how many planets there are in multiple-star systems;
4. Determine the variety of orbit sizes and planet reflectivities, sizes, masses and densities of short-period giant planets;
5. Identify additional members of each discovered planetary system using other techniques; and
6. Determine the properties of those stars that harbor planetary systems.

I personally think it would be quite interesting to learn what sort of planets, if any, orbit giant stars. However, it does seem that Kepler wouldn't be likely to find them, even if it were trying to -- for all the reasons we've already given.

--Greg

[Hungry4info]

I personally think it would be quite interesting to learn what sort of planets, if any, orbit giant stars. However, it does seem that Kepler wouldn't be likely to find them, even if it were trying to -- for all the reasons we've already given.

Several planets have been discovered orbiting giant stars through radial velocity. So far, most of them have been gas giant planets, probably the result of the biased nature of the radial velocity method.

[Greg Hullender]

Several planets have been discovered orbiting giant stars through radial velocity.

Not that I can tell. The most massive star listed in the Extrasolar Planets Encyclopedia has a mass 4.5 times that of the Sun. Giant stars start at 10x the mass of the Sun.

http://www.exoplanet.eu/catalog-all.php?&a...=8&more=yes

I'd be interested to learn otherwise, though. What's your source?

EDIT: Nevermind; it's radius, not mass, and the Encyclopedia gives 21 like that -- none smaller than 2.6 times the mass of Jupiter.

--Greg

[Hungry4info]

the Encyclopedia gives 21 like that -- none smaller than 2.6 times the mass of Jupiter.

Ah, that sounds right. I couldn't recall at the time I made my post if all of them were gas planets, or if there was a Neptune somewhere in there, thus the use of "most".

[Guest_PhilCo126_*]

During yesterday's Belgian Association for Astronomy's yearly meeting, some astronomers pointed out that the Kepler team will have to wait for the installation of new high precision spectrograph at Herschel Telescope at La Palma as HARPS in La Silla cannot reach Kepler's Field of View (Cygnus)...

[Greg Hullender]

A new Mission Manager update at Kepler:

http://www.kepler.arc.nasa.gov/about/manager.html

They're getting a handle on those earlier safing events -- something to do with a low-voltage power supply, but at least not a processor defect. No word on how they're planning to deal with it though.

--Greg

[imipak]

http://www.universetoday.com/2009/11/02/no...ler-until-2011/

"A glitch in the Kepler spacecraft's electronics means the space telescope will not have the ability to spot an Earth-sized planet until 2011, according to principal investigator William Borucki."

[stevesliva]

I interpreted those reports to mean that data acquisition is fine... they just need new algorithms to massage the data, and writing the software will take a couple years. No?

[Holder of the Tw...]

The article mentioned uploading the new algorithms to Kepler. That would seem to me that the data processing change will occur on the spacecraft (assuming the article got it right). No telling what you can do with the data already on the ground, at least from this news item.

[Syrinx]

I interpreted those reports to mean that data acquisition is fine... they just need new algorithms to massage the data, and writing the software will take a couple years. No?

Sort of. I read it as...

The data acquisition is ok but not as good as hoped. The data is noisier than hoped. The noise can be removed with software algorithms. The software will take a couple years to develop.

It's a major bummer but it's also completely understandable. I really wish we could build another with all the kinks worked out and send it up next month, but that's just not the way it works.

[Byran]

Kepler mission uses double differential photometry?

[Hungry4info]

I'm pretty sure so.

[Byran]

I.e. already collected for 6 months photometry is not possible to fix, since the processing is on board a space ship?