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May 25th, 2015

Hubble Spies Vast Gas Disk around Unique Massive Star

This artist’s illustration reveals a vast disk of gas surrounding a massive, bright Wolf-Rayet star (shown at center). A close companion star is pulling gas from the Wolf-Rayet, shown by the bridge of bright material connecting the two stars. This act of celestial cannibalism exposes the massive star’s hot, helium core. Some of the material, however, is escaping into space, forming the huge disk. This disk structure has never been seen before around a Wolf-Rayet star.

Credit:

NASA, ESA, and G. Bacon (STScI)
Science Credit: NASA, ESA, and J. Mauerhan (University of California, Berkeley)


May 22nd, 2015

Saturn’s 2015 opposition is May 22-23

Use Star Walk 2 on iOS or Android to find Saturn in the night sky.

Use Star Walk 2 on iOS or Android to find Saturn in the night sky.

Use Star Walk 2 on iOS or Android to find Saturn in the night sky.

Tonight – May 22, 2015 – the ringed planet Saturn reaches opposition, a big milestone for our year of observing the ringed planet! Earth passes in between Saturn and the sun on May 23 at 0200 Universal Time. For the Americas, that places Saturn’s opposition on May 22 in the evening (9 p.m. CDT).

So this is Saturn’s special day, its yearly opposition, when it is opposite the sun as seen from Earth. In other words, Saturn is opposite the sun in Earth’s sky. As a consequence, Saturn rises in the east at sunset, climbs highest up for the night at midnight and sets in the west at sunrise. It is visible all night, closest and brightest for this year. Just don’t assume this is a one-night-only event. In fact, Saturn’s opposition guarantees the ringed planet will be in good view throughout May and June 2015. Moreover, Saturn will remain a fixture of the evening sky until September or October 2015. All the while, golden Saturn shines in close vicinity of ruddy Antares, the brightest star in the constellation Scorpius the Scorpion.

Source: EarthSky


May 21st, 2015

NGC 6888: The Crescent Nebula

NGC 6888, also known as the Crescent Nebula, is a cosmic bubble about 25 light-years across, blown by winds from its central, bright, massive star. This beautiful portrait of the nebula is from the Isaac Newton Telescope at Roque de los Muchachos Observatory in the Canary Islands. It combines a composite color image with narrow band data that isolates light from hydrogen and oxygen atoms in the wind-blown nebula. The oxygen atoms produce the blue-green hue that seems to enshroud the detailed folds and filaments. NGC 6888’s central star is classified as a Wolf-Rayet star (WR 136). The star is shedding its outer envelope in a strong stellar wind, ejecting the equivalent of the Sun’s mass every 10,000 years. The nebula’s complex structures are likely the result of this strong wind interacting with material ejected in an earlier phase. Burning fuel at a prodigious rate and near the end of its stellar life this star should ultimately go out with a bang in a spectacular supernova explosion. Found in the nebula rich constellation Cygnus, NGC 6888 is about 5,000 light-years away.

Credit & Copyright: Daniel López, IAC, NASA


May 18th, 2015

NGC 2440: Cocoon of a New White Dwarf

Like a butterfly, a white dwarf star begins its life by casting off a cocoon that enclosed its former self. In this analogy, however, the Sun would be a caterpillar and the ejected shell of gas would become the prettiest of all! In the above cocoon, the planetary nebula designated NGC 2440, contains one of the hottest white dwarf stars known. The white dwarf can be seen as the bright dot near the photo’s center. Our Sun will eventually become a white dwarf butterfly but not for another 5 billion years. The above false color image was post-processed by Forrest Hamilton.

Credit: H. Bond (STScI), R. Ciardullo (PSU), WFPC2, HST, NASA


May 15th, 2015

A Rainbow Effect on Saturn’s Rings

The opposition effect, a brightness surge that is visible on Saturn’s rings when the sun is directly behind the spacecraft, is captured here as a colorful halo of light moving across Saturn’s sunlit rings.

The rainbow of color seen here is actually an artifact and a by-product of the spot’s movement and the way the color image was produced. Cassini acquires color images by taking sequential exposures using red, green and blue spectral filters, which are then composited together to form a color view. The bright patch traveled across the rings between exposures taken for this view, creating a series of three colorful spots showing its position at three separate moments.

See PIA08247 for more information about the opposition effect. PIA08267 shows a movie sequence of the bright spot traveling across the rings.

This view looks toward the sunlit side of the rings from about 9 degrees below the ringplane.

The images in this view were acquired with the Cassini spacecraft wide-angle camera on June 12, 2007, at a distance of approximately 523,000 kilometers (325,000 miles) from Saturn. Image scale is 31 kilometers (19 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov/home/index.cfm. The Cassini imaging team homepage is at http://ciclops.org.

Image Credit: NASA/JPL/Space Science Institute