August 31, 2014 — Early, fast, turbulent mixing of gas within giant molecular clouds—the birthplaces of stars—means all stars formed from a single cloud bear the same unique chemical “tag” or “DNA fingerprint,” writes computational astronomers at University of California, Santa Cruz in the journal Nature, published online on August 31, 2014. Could such chemical tags help astronomers identify our own Sun’s long-lost sibling stars? Read the UC-HiPACC press release at http://hipacc.ucsc.edu/PressRelease/sibling-stars.html and watch the movies!
Two 11-second movies shows a computational simulation of a collision of two converging streams of interstellar gas, leading to collapse and formation of a star cluster at the center.
Whodunit? A brilliant flash of ultraviolet light from supernova SN 2013cu in a galaxy 360 million light-years away in the constellation Boötes solved an enduring mystery about the origins of massive exploding stars called Type IIb core-collapse supernovae. Thanks to the intermediate Palomar Transient Factory (iPTF) pipeline, the perp of Type IIb supernovae has been identified as Wolf-Rayet. “This is the smoking gun!” exulted Peter Nugent, head of the Computational Cosmology Center at Lawrence Berkeley National Laboratory. Read the AstroShort ’Smoking Gun’ for Stellar Explosion Mystery.
While observing a galaxy known as UGC 9379 (left; image from the Sloan Digital Sky Survey) about 360 million light-years from Earth, the iPTF team used a 1.2-meter robotic telescope at Palomar Observatory to discover a new supernova, SN 2013cu (right, marked with an arrow; image from a 1.5-meter robotic telescope, also at Palomar).
Loud and twisted: some supermassive black holes at the centers of galaxies have twisted magnetic fields so powerful they counteract the colossal pull of their gravity—allowing clouds of accreting gas or other objects literally to levitate temporarily in place above the black hole instead of plunging into the maw. That’s the conclusion of one UC Berkeley researcher and three coauthors after comparing their computational model to empirical measurements of not just one or two, but of 76 supermassive black holes in loud radio galaxies and blazars. The new findings may mean that theorists must re-evaluate their understanding of how supermassive black holes behave. Read the AstroShort “Magnetically Levitating Black Holes.”
A computer simulation shows gas (yellow) falling in the direction of a central black hole (too small to be seen). Twin jets (blue), strongly focused by spiral magnetic field lines, shoot out towards the top and bottom, perpendicular to the plane of the rotating accretion disk. Credit: Alexander Tchekhovskoy/LBNL
Moon rocks brought back by the Apollo astronauts revealed that the lunar mineral apatite is everywhere, from the ancient lunar highlands to the young lunar maria (lava seas). Much of it is rich in hydrogen. Taking hydrogen as a proxy for water, the evidence suggested that the material from which the Moon formed might have been as wet as that which formed Earth. Apatite became widely adopted as a yardstick for measuring hydrogen—and thus water—in the Moon. But a new computational model of how apatite crystalized from lunar magmas, devised by Jeremy W. Boyce at UC Los Angeles and four coauthors, now reveals that apatite, the mineral on which scientists have long relied, “cannot be trusted.” Read the AstroShort “Drying Out the Moon?”
Photomicrograph of Apollo 11 lunar sample 10044,644 maps density of its polished surface: denser materials reflect more electrons and look lighter gray. Pinkscale version of image highlights density variations for a crystal of apatite. Credit: Jeremy Boyce, UCLA
If the stars observed by NASA’s Kepler spacecraft are statistically representative of those in our own solar neighborhood of the Milky Way galaxy, then “Earth-size planets are common around nearby Sun-like stars,” conclude Erik A. Petigura and Geoffrey W. Marcy from the University of California, Berkeley and Andrew W. Howard from the University of Hawaii. They were led to that conclusion by a monumental statistical analysis of Kepler data completed with the help of the Carver supercomputer at the Department of Energy’s (DOE’s) National Energy Research Scientific Computing Center (NERSC). Read the AstroShort “Not So Rare Earths”.
Field of view of the Kepler space telescope, located in the constellation Cygnus, just above the plane of the Milky Way Galaxy. Credit: NASA