Astronomy Picture of the Day for Jan. 29th

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2012 January 29
See Explanation.  Clicking on the picture will download the highest resolution version available.

Molecular Cloud Barnard 68
Image Credit: FORS Team, 8.2-meter VLT Antu, ESO 

 

Explanation: Where did all the stars go? What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud. Here, a high concentration of dust and molecular gas absorb practically all the visible light emitted from background stars. The eerily dark surroundings help make the interiors of molecular clouds some of the coldest and most isolated places in the universe. One of the most notable of these dark absorption nebulae is a cloud toward the constellation Ophiuchus known as Barnard 68, pictured above. That no stars are visible in the center indicates that Barnard 68 is relatively nearby, with measurements placing it about 500 light-years away and half a light-year across. It is not known exactly how molecular clouds like Barnard 68 form, but it is known that these clouds are themselves likely places for new stars to form. In fact, Barnard 68 itself has been found likely to collapse and form a new star system. It is possible to look right through the cloud in infrared light.

Astronomy Picture of the Day for October 9th

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

SDSS J102915+172927: A Star That Should Not Exist
Image Credit: ESO, DSS2 

 

Explanation: Why does this star have so few heavy elements? Stars born in the generation of our Sun have an expected abundance of elements heavier than hydrogen and helium mixed into their atmospheres. Stars born in the generation before our Sun, Population II stars, the stars that created most of the heavy elements around us today, are seen to have some, although fewer, elements heavier than H and He. Furthermore, even the elusive never-seen first stars in the universe, so-called Population III stars, are predicted to have a large mass and a small but set amount of heavy elements. Yet low-mass Milky Way star SDSS J102915+172927, among others, appears to have fewer metals than ever predicted for any stars, including at least 50 times less lithium than came out of the Big Bang. The unusual nature of this star, initially cataloged by the Sloan Digital Sky Survey (SDSS) and pictured above, was discovered by detailed spectroscopic observations by a large VLT telescope in Chile. Many models of star formation indicate that such a star should not even form. Research is ongoing, however, with one leading hypothesis holding that fragile primordial lithium was destroyed in the star’s hot core.