By Ken Croswell. April 1, at am. Like two great songwriters working side by side and inspiring each other to create their best work, the Magellanic Clouds spawn new stars every time the two galaxies meet.
Visible to the naked eye but best seen from the Southern Hemisphere, the Large and Small Magellanic Clouds are by far the most luminous of the many galaxies orbiting the Milky Way. New observations reveal that on multiple occasions the two bright galaxies have minted a rash of stars simultaneously , researchers report March 25 in Monthly Notices of the Royal Astronomical Society: Letters.
Their orbit is elliptical, which means they periodically pass near each other. During the last encounter, which happened million to million years ago, the smaller galaxy probably smashed right through the larger, Besla says, which sparked the current outbreak of star birth. Based on the star formation peaks, the period between Magellanic encounters has decreased from a billion to half a billion years.
Besla attributes this to a process known as dynamical friction. The gravitational pull of this dark matter wake slows the smaller galaxy, shrinking its orbit and reducing how much time it takes to revolve around the Large Magellanic Cloud. The future for the two galaxies may not be so starry, however. If so, the Magellanic Clouds, now separated by 75, light-years, may never approach each other again, putting an end to their most productive episodes of star making, just as musicians sometimes flounder after leaving bandmates to embark on solo careers.
A new cosmic burst suggests at least some might be from a mid-sized black hole ripping up a star. Disintegrating exoplanets, like the one illustrated here, spill their guts into space in a long cometlike tail. Scientists are on the hunt for black holes that could have formed before the first stars and galaxies. Onboard a ship in the Mediterranean Sea, workers prepare launching equipment for the installation of the underwater neutrino telescope KM3NeT.
