Blue M98, variant

Blue M98, variant

Edited European Southern Observatory image of the galaxy M98. Color/processing variant.

Original caption: The colour blue has many associations — coldness, sadness, serenity. However, the colour holds a completely different meaning for astronomers, as demonstrated by the edge-on spiral galaxy Messier 98. Messier 98, also known as NGC 4192, is located approximately 50 million light-years away in the constellation of Coma Berenices (Berenice’s Hair). In this spectacular image from ESO’s New Technology Telescope (NTT), the galaxy’s perimeter, rippled with gas and dust, is dotted with pockets of blueish light. These are regions filled with very young stars, which are so hot that they glow with a bright blue hue. These young stars are burning at such high temperatures that they are emitting fierce radiation, burning away some of the dense material that surrounds them. In total, Messier 98 is thought to contain one trillion stars! The NTT is a 3.58-metre telescope at the La Silla Observatory, which pioneered the use of active optics and was the first in the world to have a computer-controlled main mirror.

Posted by sjrankin on 2018-06-05 02:39:29

Tagged: , Messier 98 , NGC 4192 , 5 June 2018 , Edited , ESO , European Southern Observatory , Galaxy , M98 , Spiral Galaxy

Variable Stars in a Distant Spiral Galaxy

Variable Stars in a Distant Spiral Galaxy

Edited Hubble Space Telescope image of a very pretty spiral galaxy.

Original caption: A NASA Hubble Space Telescope (HST) view of the magnificent spiral galaxy NGC 4603, the most distant galaxy in which a special class of pulsating stars called Cepheid variables have been found. It is associated with the Centaurus cluster, one of the most massive assemblages of galaxies in the nearby universe. The Local Group of galaxies, of which the Milky Way is a member, is moving in the direction of Centaurus at a speed of more than a million miles an hour under the influence of the gravitational pull of the matter in that direction. Clusters of young bright blue stars highlight the galaxy’s spiral arms. In contrast, red giant stars in the process of dying are also found. Only the very brightest stars in NGC 4603 can be seen individually, even with the unmatched ability of the Hubble Space Telescope to obtain detailed images of distant objects. Much of the diffuse glow comes from fainter stars that cannot be individually distinguished by Hubble. The reddish filaments are regions where clouds of dust obscure blue light from the stars behind them. This galaxy was observed by a team affiliated with the HST Key Project on the Extragalactic Distance Scale. Because NGC 4603 is much farther away than the other galaxies studied with Hubble by the Key Project team, 108 million light-years, its stars appear very faint from the Earth, and so accurately measuring their brightness, as is required for distinguishing the characteristic variations of Cepheids, is extremely difficult. Determining the distance to the galaxy required an unprecedented statistical analysis based on extensive computer simulations.

Posted by sjrankin on 2014-09-05 05:31:26

Tagged: , Centaurus , Cepheid , HST , Hubble Space Telescope , Milky Way , Pulsar , Spiral Galaxy NGC 4603 , 4 September 2014 , Edited , NASA , Galaxy , Spiral Galaxy