Astronomía, Astronomy.

Spiral galaxy ESO 137-001

This Hubble image shows ESO 137-001, a galaxy located in the southern constellation of Triangulum Australe (The Southern Triangle) — a delicate and beautiful spiral galaxy, but with a secret. The image not only captures the galaxy and its backdrop in stunning detail, but also something more dramatic — intense blue streaks streaming outwards from the galaxy, seen shining brightly in ultraviolet light.
These streaks are actually hot young stars, encased in wispy streams of gas that are being torn away from the galaxy by its surroundings as it moves through space. This violent galactic disrobing is due to a process known as ram pressure stripping — a drag force felt by an object moving through a fluid . The fluid in question here is superheated gas, which lurks at the centres of galaxy clusters.
This image combines NASA/ESA Hubble Space Telescope observations with data from the Chandra X-ray Observatory.

Credit: NASA, ESA, CXC

The Seven Sisters, also known as the Pleiades star cluster, looking over  Reunion & Mauritius Islands in a moonlit Indian Ocean captured by NASA astronaut Karen Nyberg from the International Space Station 19:57 GMT 25 August 2013.
Fragile Oasis

NGC 1999 LRGB “The Dolphin in The Grotto” Credit: Tony Hallas Astrophoto


A photograph of our sun in a combination of three wavelengths of light.

☽ ⁎ ˚ * ☀ Mystique, autumn, nature ✵ ⁎ * ☾

New molecules around old stars

Using ESA’s Herschel space observatory, astronomers have discovered that a molecule vital for creating water exists in the burning embers of dying Sun-like stars.
When low- to middleweight stars like our Sun approach the end of their lives, they eventually become dense, white dwarf stars. In doing so, they cast off their outer layers of dust and gas into space, creating a kaleidoscope of intricate patterns known as planetary nebulas.
These actually have nothing to do with planets, but were named in the late 18th century by astronomer William Herschel, because they appeared as fuzzy circular objects through his telescope, somewhat like the planets in our Solar System.
Over two centuries later, planetary nebulas studied with William Herschel’s namesake, the Herschel space observatory, have yielded a surprising discovery.

Like the dramatic supernova explosions of weightier stars, the death cries of the stars responsible for planetary nebulas also enrich the local interstellar environment with elements from which the next generations of stars are born.
While supernovas are capable of forging the heaviest elements, planetary nebulas contain a large proportion of the lighter ‘elements of life’ such as carbon, nitrogen, and oxygen, made by nuclear fusion in the parent star.
A star like the Sun steadily burns hydrogen in its core for billions of years. But once the fuel begins to run out, the central star swells into a red giant, becoming unstable and shedding its outer layers to form a planetary nebula.

The remaining core of the star eventually becomes a hot white dwarf pouring out ultraviolet radiation into its surroundings.
This intense radiation may destroy molecules that had previously been ejected by the star and that are bound up in the clumps or rings of material seen in the periphery of planetary nebulas.
The harsh radiation was also assumed to restrict the formation of new molecules in those regions.
But in two separate studies using Herschel astronomers have discovered that a molecule vital to the formation of water seems to rather like this harsh environment, and perhaps even depends upon it to form. The molecule, known as OH+, is a positively charged combination of single oxygen and hydrogen atoms.

In one study, led by Dr Isabel Aleman of the University of Leiden, the Netherlands, 11 planetary nebulas were analysed and the molecule was found in just three.
What links the three is that they host the hottest stars, with temperatures exceeding 100 000ºC.
“We think that a critical clue is in the presence of the dense clumps of gas and dust, which are illuminated by UV and X-ray radiation emitted by the hot central star,” says Dr Aleman.
“This high-energy radiation interacts with the clumps to trigger chemical reactions that leads to the formation of the molecules.”

Image credit: Hubble image: NASA/ESA/C. Robert O’Dell (Vanderbilt University) Herschel data: ESA/Herschel/PACS & SPIRE/ HerPlaNS survey/I. Aleman et al.

Twelve million light years into the stellar wilderness

M81 and Arp’s Loop


Hoag’s Object - a ring galaxy discovered in 1950 by astronomer Art Hoag, who initially thought it to be a planetary nebula. A nearly perfect ring of hot, blue stars pinwheels about the yellow nucleus of this unusual galaxy [1521x1489]