http://kepler.nasa.gov/Mission/discoveries/candidates/

“Many scientists are doing follow-up observing with ground-based telescopes to confirm discoveries. Confirmed planets are announced as discoveries.”

http://www.astronomynow.com/news/n1106/01galaxies/

For one article on how elliptical gaxies are still forming stars – and presumaby planets too. Okay they may be relatively metal poor but there are still probably planets forming.

Of coures given their vast distance from us it is going to be incredibly hard to detect anyexioplanets in Elliptical galaxies.Far as I know only one exoplanet has ever been found in another galaxy :

http://www.scientificamerican.com/article.cfm?id=planet-spotted-in-andromeda-galaxy-2009-06

and that was in the Andromeda galaxy.

Although some exoplanets may have been born in dwarf galaxies that were absorbed into our MilkyWay suchas the Saggittarius and Canis Major dwarfs.

Finally this item :

http://news.discovery.com/space/suns-twin-is-an-optimum-seti-target-120426.html?fb_ref=fb2&fb_source=profile_oneline

may be of interest here – a solar twin that’s more exact than any yet found and a promising target for future study.

@2. Chris : “A green tennis ball representing a star. Phil, there are no green stars! “

Well, actually there is Zubeneschamali (Beta Librae) which is often said to be green to the unaided human eye. (Click my name for one source.) Soemtiems it looks green to me too although how much of that is my own imagination and atmospheric conditions is an open question.

There’s also some like Antares B, the red supergiants companion star which may also be green although it’s also possibly just an optical illusion created by contrast with its larger primary.

@ 7. SLC :

I have been having a running discussion over at Larry Moran’s blog with an old earth creationist, who calls himself Denny, and who claims that planetary systems can only be formed in spiral galaxies.

A lot of ellipticals formed from merging spiral galaxies – and in the future our Milky Way barred spiral & spiral galaxy M31 will collide and form such an elliptical – so I’d say that can’t be right!

Think I read somewhere online that one recent study has suggested that some stars still form inside elliptical galaxies contrary to previous thinking so that, again, would seem to indicate planets could well form in such ellipticals too.

The link seems to indicate that a rocky core is required to accumulate the outer gas layers of Jupiter type planets. I have embolden the relevant text. I must admit that that came as a surprise to me as it indicates that such planets must have a solid core, i.e. they can’t be entirely gas.

The answer is yes, based on the authors’ comparison of metallicity — in nearby stars and stars with known planets — to star clusters in two elliptical galaxies. While many factors have been considered that could affect a galactic habitable zone, Suthar and McKay focus tightly on metallicity, with planet formation dependent upon the presence of elements heavier than hydrogen and helium. Results from Kepler have backed the notion that metallicity and planets go together, although it’s a correlation that has so far been established only for large planets like the gas giants that are the easiest for us to detect. We can’t be sure that the correlation goes all the way down to planets the size of the Earth, but the idea seems logical.

After all, we think Jupiter-class planets formed by the accretion of gases around a rocky core, and the formation of that core may be similar to the formation of Earth-sized planets. The authors think the correlation between stellar metallicity and planets will extend to smaller worlds, while recent exoplanet discoveries help us explore the relationship and extend our thinking to elliptical galaxies. The galaxies in question are M87 and M32, and the investigation is one that invokes the history of star-forming materials. After all, heavy elements are produced inside stars, so the concentration of metals depends critically on the generations of earlier stars.

I don’t think heavier elements are required for planet formation (you could have a gas giant without them). Habitable planets, as we know it, would require elements such as oxygen, iron, etc. I think there was some questions if elliptical and other galaxy types outside of spiral, would have similar heavy metal content to our Sun in their various stars (and subsequently planets), and it looks like the answer is YES!

The blog was based on an article published in what I believe is a reputable scientific journal: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8490356

Oh and for those interested, the galaxy they examined was M32: http://en.wikipedia.org/wiki/Messier_32

Thanks for the information. I was unaware that the presence of heavier elements was required for planet formation, although that makes sense as a solid core would seem to be required to start the process.

You are in luck. Sure your “Old Earth Creationist” friend is unlikely to believe any source you send him, but just the other day I read an interesting article about habitable zones in other galaxies, and this one specifically talks about habitable zones in elliptical galaxies. http://www.centauri-dreams.org/?p=22613

If you don’t want to read the whole blog, the short answer is that the metal levels are right that earth like planets can form in the particular elliptical galaxy they looked at, as long as the star in question is sufficiently far from the jet caused by the supermassive black hole at the center.