Scientific discoveries across all fields just keep coming and coming. Here's a small assortment of goodies from the past couple of weeks.
How do you form planets around stars in triple systems?
You feed them of course. New data from the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in northern Chile has probed the gas and dust in a young stellar system, GG Tauri-A some 460 light years away. Here a single star is orbiting some 35 astronomical units (AU) from a pair of stars that also orbit around each other at only 3 to 4 AU separation - it's a hierarchical trinary star system.
This entire stellar family is orbited by a ring of gas and dust (about 200 AU out) and a more extended disk of material going out to 800 AU. And there is an inner disk of material surrounding the unpaired star. Confused? Yes, it's complicated. Here's an artist's impression:
The newsworthy discovery is that there are 'clumps' of gas apparently flowing between the outer ring and disk and the disk around the lonesome star towards the center. This helps explain how that star can have a surrounding disk - which would otherwise get gobbled up by its host star quite quickly - and suggests that there is enough material flowing through for planet formation to have a chance of happening.
In other words, even in such a complex hierarchy of stars the opportunity exists for building worlds.
What does a wobbling 'Death Star' moon tell us?
Saturn's strange looking moon Mimas (nicknamed the 'Death Star' because, well, because that's what it looks like) sits in what is termed 'tidal lock' - just like the Earth's moon it always faces Saturn the same way, its day is equal to its year. But data from NASA's Cassini mission show that Mimas actually librates, or wobbles, around its polar axis too much to be a nice uniform sphere through and through.
There are a few possible explanations. The interior, denser, core of Mimas (its outsides are dirty water ice) might be shaped like a football (of the US variety) - in other words a bit pointy. This elongation, combined with a slightly non-circular orbit, could cause those wobbles.
Another possibility is that Mimas is hiding an interior ocean of liquid water, under about 20 to 30 kilometers of ice. That ocean would let the outer shell of the moon wobble more by isolating it from the inner regions of the moon - a 'floating' surface if you will.
An ocean is intriguing, not least because such dark territories likely exist in places like Europa, or Titan, but also because they could be prime real estate for life sealed away from the Sun. The catch? It's not clear how tiny Mimas, only 400 kilometers across, could stay warm enough inside to maintain an ocean like this. Time will tell what's happening here.
What does a comet smell of?
Rotten eggs, an unclean stable, formaldehyde, and a touch of almond, that's what. At least that would be what a very, very sensitive human nose might detect. The ESA Rosetta mission, currently in a delicate orbit around the nucleus of comet 67P/C-G, has been using its Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) instrument to examine what's starting to boil off along the nucleus - along with more ordinary stuff like water, carbon dioxide, carbon monoxide and methane - as the comet arcs closer to the Sun.
In the mix are small amounts of ammonia (filthy stable), methanol (really bad, toxic, vodka), formaldehyde, hydrogen sulphide (rotten eggs), hydrogen cyanide (almonds), sulfur dioxide (vinegary) and carbon disulphide (sweet and aromatic).
Scientifically this is all tremendously interesting. The chemical makeup of a comet is a fingerprint to its origins and history, and this first sniff bodes well for a wealth of interesting molecules boiling off 67P/C-G over the coming months - towards its closest pass to the Sun in August 2015. That chemistry also offers clues to the smorgasbord of organic material that was cooking up in our young solar system 4.5 billion years ago - some of which likely ended up on the surface of the Earth.