November 28, 2014

15.04.10- Do We Know the Future of our Sun?

(Credit: Oliver Beatson).

(Credit: Oliver Beatson).

  You Are Here!

    Our modern understanding of stellar evolution states that our Sun is a middle-aged main sequence star, destined to bellow up into a Red Giant in a few billion years and eventually wind up as a degenerate white dwarf embedded in a shroud of a planetary nebula. Looking out at the stars in various stages of evolution in our galaxy, we see systems that have done just that. These Red Giants often exhibit a rhythmic oscillation as their atmospheres swell and contract, but about one third also display a longer five year variation that scientists do not completely understand. Now, a study conducted by the European Southern Observatories’ Very Large Telescope (VLT) is looking into this mystery by studying 58 sun-like stars towards their elderly Red Giant stage located in the Large Magellanic Cloud. Known since the 1930’s, this mystery has baffled astronomers. “Astronomers are left in the dark, and for once, we do not enjoy it,” stated Christine Nicholls of Australia’s Mount Stromlo Observatory. Some of the long term pulsations could be explained by the presence of an unseen binary companion, but not all. This phenomenon is of special interest to astrophysicists because our own Sun may one day throw similar temper tantrums. Could stellar evolution be in need of tweaking?

4.10.9:A Gamma-Ray Burst for the Record Books.

An IR, Optical & UV Composite of GRB 090423 as seen from Swift. (Credit: NASA/Swift/Stefan Immler).

An IR, Optical & UV Composite of GRB 090423 as seen from Swift. (Credit: NASA/Swift/Stefan Immler).

A Gamma-ray burst from the primordial universe sent astronomers reeling earlier this year with the most distant sighting yet. The burst was picked up by NASA’s Swift spacecraft on April 23, 2009 at 3:55 EDT. E-mails and instant messages flew to observatories around the globe as astronomers raced to pin-point the fading afterglow. Dubbed GRB 090423, (get the year/month/day thing?) This burst measures in at a redshift of 8.2, or a distance of 13.035 billion light years. This hails from a time when the universe was a tender young age of only 630 years old, young, compared to our circa 14 billion year current age. The old record was a red shift of 6.7 set in September 2008. the current “holy grail” in cosmology is to break the “redshift 10″ barrier, which may well happen in the coming year. A gamma-ray burst occurs when a super massive star collapses into a black hole, briefly creating a “hyper-nova” in the process. Such events are the most luminous in the universe and are thought to have been common amoung first generation stars. Backup observations were provided by Italy’s Galileo national telescope in the Canary Islands and the ESO’s Very Large Telescope in Chile.