A Changing Sky

Gazing up at the sky while reading the old texts one would not be amiss in believing that the stars never change. Indeed there are many who insist vehemently that the stars are eternal and unchanging. But the stars do indeed change, often quite visibly, sometimes within the span of a human lifetime.

VLT/SPHERE image of the star L2 Puppis and its surroundings
A VLT/SPHERE image of L2 Puppis showing the enveloping cloud of gas and dust representing an early stage planetary nebula. Image credit ESO/P. Kervella used under Creative Commons 4.0

One such star is L2 Puppis.

A bright star, one of the few naked eye variable stars that could be seen to fade and reappear without the aid of a telescope much like the far more famous stars Mira and Algol. On star charts the star is found prominently drawn at magnitude 4, buf if you attempt to locate it today you will not find it without the use of a telescope.

I first encountered this star quite recently while starhopping through southern Puppis with an 8″ telescope from the driveway. The chart showed two bright stars close together, L1 Pup and L2 Pup, while the view in the finder ‘scope showed only one bright star.

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International Team on Keck Observatory Strengthens Big Bang Theory

W. M. Keck Observatory press release

An international team of scientists using the most powerful telescope on Earth has discovered the moments just after the Big Bang happened more like the theory predicts, eliminating a significant discrepancy that troubled physicists for two decades. The discovery will be published in the international journal Astronomy & Astrophysics on June 6.

Stellar Lithium
The image illustrates the detailed modelling of a small piece of the surface of an old metal-poor star used to derive its abundance of lithium-6. Image credit Karin Lind, Davide De Martin.
One of the most important problems in physics and astronomy was the inconsistency between the lithium isotopes previously observed in the oldest stars in our galaxy, which suggested levels about two hundred times more Li-6 and about three to five time less Li-7 than Big Bang nucleosynthesis predicts. This serious problem in our understanding of the early Universe has invoked exotic physics and fruitless searches for pre-galactic production sources to reconcile the differences.

The team, led by Karin Lind of the University of Cambridge, has proven the decades-old inventory relied on lower quality observational data with analysis using several simplifications that resulted in spurious detections of lithium isotopes.

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