Monicks: Unleashed

Tag: NASA

  • Astronomy Picture of the Day | Hubble Remix: Active Galaxy NGC 1275

    Hubble Remix: Active Galaxy NGC 1275
    Credit: Data – Hubble Legacy Archive, ESA, NASA

    Explanation: Active galaxy NGC 1275 is the central, dominant member of the large and relatively nearby Perseus Cluster of Galaxies. Wild-looking at visible wavelengths, the active galaxy is also a prodigious source of x-rays and radio emission. NGC 1275 accretes matter as entire galaxies fall into it, ultimately feeding a supermassive black hole at the galaxy’s core. This color composite image, recreated from archival Hubble Space Telescope data, highlights the resulting galactic debris and filaments of glowing gas, some up to 20,000 light-years long. The filaments persist in NGC 1275, even though the turmoil of galactic collisions should destroy them. What keeps the filaments together? Observations indicate that the structures, pushed out from the galaxy’s center by the black hole’s activity, are held together by magnetic fields. Also known as Perseus A, NGC 1275 spans over 100,000 light years and lies about 230 million light years away.

    hubblesite.org

  • Astronomy Picture of the Day | The Dark Tower in Scorpius

    Image Credit & Copyright: Thomas V. Davis

    This object is an obscure cometary globule in Scorpius. I think the name came from John Gleason who imaged it in h-alpha. Actually only a few images of it exist, all I believe taken in h-alpha except for David Malin’s color film version. Its a cool target and seems to be the southern hemisphere’s equivalent to Vdb 142 (IC1396A). I hope you enjoy it.

    Bright rimmed globules and their more evolved cousin the cometary globule represent fascinating dynamic structures formed by the interplay of cold molecular clouds and hot ionizing stars. Typically the head of the globule faces a hot O-type star. Intense radiation from the star boils away lower density gas from the head. The evaporated rim of gas becomes ionized by the stars ultraviolet flux forming a bright glowing rim we associate with many of these globules including CG4. Intense stellar winds from the ionizing star evaporate gas and dust away from the head forming the “tail” and completing the cometary shape. The globules are known to be the birthplace of low mass stars. Stars form within the globules by the mechanism known as “radiation driven implosion”. This process occurs when ultraviolet flux from a hot star compresses surviving clumps of cold molecular gas eventually causing collapse and core formation within the dense compact clouds. Lower and intermediate mass stars ultimately form from the compact gas and dust within the globules.

    In silhouette against a crowded star field toward the constellation Scorpius, this dusty cosmic cloud evokes for some the image of an ominous dark tower. In fact, clumps of dust and molecular gas collapsing to form stars may well lurk within the dark nebula, a structure that spans almost 40 light-years across the gorgeous telescopic view. Known as a cometary globule, the swept-back cloud, extending from the lower left to the head (top of the tower) right and above center, is shaped by intense ultraviolet radiation from the OB association of very hot stars in NGC 6231, off the right edge of the scene. That energetic ultraviolet light also powers the globule’s bordering reddish glow of hydrogen gas. Hot stars embedded in the dust can be seen as bluish reflection nebulae. This dark tower, NGC 6231, and associated nebulae are about 5,000 light-years away.

  • Astronomy Picture of the Day | Westerlund 2

    Image credit: NASA/CXC/Univ. de Liege/Y. Nael et al.

    This Chandra X-ray Observatory image shows Westerlund 2, a young star cluster with an estimated age of about one or two million years. Until recently little was known about this cluster because it is heavily obscured by dust and gas. However, using infrared and X-ray observations to overcome this obscuration, Westerlund 2 has become regarded as one of the most interesting star clusters in the Milky Way galaxy. It contains some of the hottest, brightest and most massive stars known.

    This Chandra image of Westerlund 2 shows low energy X-rays in red, intermediate energy X-rays in green and high energy X-rays in blue. The image shows a very high density of massive stars that are bright in X-rays, plus diffuse X-ray emission.

    An incredibly massive double star system called WR20a is visible as the bright yellow point just below and to the right of the cluster’s center. This system contains stars with masses of 82 and 83 times that of the Sun. The dense streams of matter steadily ejected by these two massive stars, called stellar winds, collide with each other and produce copious amounts of X-ray emission. This collision is seen at different angles as the stars orbit around each other every 3.7 days. Several other bright X-ray sources may also show evidence for collisions between winds in massive binary systems.