beecee Posted April 2, 2018 Posted April 2, 2018 An Interesting article and paper this morning...... https://phys.org/news/2018-04-gravitational-lensing-sun-like-star-massive.html Gravitational lensing by sun-like star in massive cluster reveals blue supergiant 9 billion light years away: Thanks to a rare cosmic alignment, astronomers have captured the most distant normal star ever observed, some 9 billion light years from Earth. While astronomers routinely study galaxies much farther away, they're visible only because they glow with the brightness of billions of stars. And a supernova, often brighter than the galaxy in which it sits, also can be visible across the entire universe. Beyond a distance of about 100 million light years, however, the stars in these galaxies are impossible to make out individually. But a phenomenon called gravitational lensing - the bending of light by massive galaxy clusters in the line of sight—can magnify the distant universe and make dim, far away objects visible. Typically, lensing magnifies galaxies by up to 50 times, but in this case, the star was magnified more than 2,000 times. It was discovered in NASA Hubble Space Telescope images taken in late April of 2016 and as recently as April 2017. Read more at: https://phys.org/news/2018-04-gravitational-lensing-sun-like-star-massive.html#jCp the paper: https://www.nature.com/articles/s41550-018-0430-3 Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens: Abstract: Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to ~50. Here we report an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than ×2,000. A separate image, detected briefly 0.26″ from Lensed Star 1, is probably a counterimage of the first star demagnified for multiple years by an object of ≳3 solar masses in the cluster. For reasonable assumptions about the lensing system, microlensing fluctuations in the stars’ light curves can yield evidence about the mass function of intracluster stars and compact objects, including binary fractions and specific stellar evolution and supernova models. Dark-matter subhaloes or massive compact objects may help to account for the two images’ long-term brightness ratio. <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Interesting extract from the article...... "The astronomy team also used Icarus to test and reject one theory of dark matter - that it consists of numerous primordial black holes lurking inside galaxy clusters—and to probe the make-up of normal matter and dark matter in the galaxy cluster".
Recommended Posts