All Space Considered, Feb 2015 (Exoplanets)

Exoplanets

Giant Ring System

So January 2015 was a good month for exoplanet news.  All kinds of cool findings were made.  The lead off here has a very cool video to go with it.

There are lots of other pretty artist depictions of this giant ring system, but I like this video because it shows the actual transit data along the bottom.  The transit method is one of the primary ways we've detected exoplanets in the past 10-20 years and usually the data tell us about the planet itself.  In this case, the transit data packed quite a surprise, one whose best explanation at the moment is a huge ring system.  How huge?  When we think "ring system," almost universally people will think of Saturn, with good reason.  It has by far the largest and most prominent ring system in our sun's domain.  If the data we collected really do show a ring system as hypothesized, here's what the behemoth would look like in our sky if placed where Saturn is.

Yup, that's our moon on the left, getting dwarfed

Could this possibly be such a ring system that seemingly only science fiction would dream up?  For me, the most convincing part is the symmetry, that the star had to pass both into and out of the ring system.  I suppose the tilt of the rings and the orbit of the planet with respect to Earth's line of sight to the star might provide enough degrees of freedom to fit any data; but enough experts are convinced that I'm going to believe it for now.

Doubled the Discovered Goldilocks Planets

While the ring system makes for pretty pictures, what exoplanet hunters are really after is Earth-like planets, ones in the "Goldilocks" zone where liquid water on the surface is likely and roughly the same size as Earth.  Well, we found 8 more, bringing the overall total to 16.  Such planets are of extreme interest for at least two reasons.  The first is that human-like life is most likely to exist on such a planet.  There is always the possibility that non-human-like life exists on other planets, but we're of course most interested in the life that we are most compatible with.  The second reason is exploring the possibility of human life somewhere besides Earth.  Mars occasionally comes up as a candidate, but its thin atmosphere makes it a pretty poor candidate.  It is still nonetheless the best candidate in the solar system.  That means to find a truly great candidate, we must look beyond our solar system.

Super-Earths Superer than Earth at Holding Oceans

Another point of discussion was theoretical work done regarding the development of oceans and a planet's ability to retain one oceans once they had been established.  It is, of course, nice if a planet has liquid water.  However, if it is like Mars, that water disappears quickly and the window of opportunity for life as we know it to form is over.  Harvards Center for Astrophysics has determined that planets 2-4 times the mass of Earth seem to be the best at both forming oceans and retaining them once formed.  The main impact of this research is that if we want to look for liquid water, we should target searches for planets in this mass range most heavily.

It bears remarking that the rate of exoplanet discovery in the past 10 years has been just plain crazy.  Not long ago, we weren't even sure if we could detect exoplanets.  Now, we've found more than all but the most popular people have friends on Facebook.  It's almost certain that we'll find more than the single most popular person has friends on Facebook soon.  "Friends on Facebook" may seem a frivolous measure, but I bring it up because it means that for each person you have had any personal interaction with, there is an exoplanet that has been discovered and confirmed.  Given that all of this has happened within a relatively small region of our own galaxy, which itself is only one of hundreds of billions in the observable Universe, and the sheer scale of the diversity and possibilities become incomprehensible rather quickly.

NGTS

In the vein of accelerated discovery, a new planet-hunting telescope saw first light in January. I'm not sure if this was indeed mentioned at All Space Considered, but I think it's important enough to mention.  To date, the space-based Kepler telescope has been doing the lion's share of the exoplanet discovery.  It has been hobbled of late by failing mechanics, but had long surpassed its original mission length and still continues to amazing work even in its current state.  NGTS is a ground-based telescope that will look at much brighter stars than Kepler and sweep out a larger region of the sky than Kepler.  Like Kepler, much of NGTS's work will be to provide candidates for follow-on observations with more specialized telescopes.  Standard transit observations can deduce size, mass and orbit of an exoplanet.  Follow-on measurements use spectroscopy while the planet is in-transit to determine the chemical composition and depth of the planet's atmosphere.