ikenbot:

When Supermassive Supergiants Go Superboom

Article by Phil Plait via Slate

I have long been fascinated by gamma-ray bursts (or GRBs). These are incredibly violent events: It’s like taking the Sun’s entire lifetime energy output and cramming into a single event that lasts for mere seconds! The energy emitted is so intense, so bright, we can see GRBs from a distance of billions of light years.

Gamma rays themselves are just a form of light, like the kind we see, but with huge energy; each photon is packed with millions or billions of times the energy in a single photon of visible light. Only the most energetic events in the Universe can make them, so if we detect a burst of them coming from the sky, we know something literally disastrous has happened.

We know GRBs come in many flavors. Some last literally for milliseconds, while others stretch on for minutes. We also know different events can cause them, too. Short ones seem to come from merging neutron stars, ultra dense compact objects left over after stars explode. The longer ones occur when massive stars explode, leaving their cores to collapse. In both cases, the huge blast of high-energy gamma rays signals the birth of a black hole.

But astronomers were recently surprised to find a third type of GRB, one that lasts not for minutes, but for hours. Whatever these objects are, they don’t just flash with light, they linger, blasting out far, far more gamma rays for far, far longer than was previously thought. What could do such a thing?

Several ideas were put forth, but new observations provided the linchpin: an ultra-long-duration GRB occurred on Christmas Day in 2010, and its distance was found to be a soul-crushing 7 billion light years away, about halfway across the visible Universe! This left only one possible candidate for the progenitor: a hugely massive star, one so big it dwarfs the Sun into insignificance.

Continue to Full Article..

ikenbot:

SN 1006: New X-Ray View of A Thousand-Year-Old Cosmic Tapestry

Over a millenia ago Earth witnessed an explosion in the heavens, that explosion was later discovered to be a supernova. Now, new data from NASA’s Chandra X-ray observatory adds to the awesome factor of SN 1006 and supernovae like it, which provides new details about the remains of this exploded star. As noted in Chandra’s official site:

“The Chandra data provides the best map to date of the debris field including information on important elements expanding into space.”

A new image of SN 1006 from NASA’s Chandra X-ray Observatory reveals this supernova remnant in exquisite detail. By overlapping ten different pointings of Chandra’s field-of-view, astronomers have stitched together a cosmic tapestry of the debris field that was created when a white dwarf star exploded, sending its material hurtling into space. In this new Chandra image, low, medium, and higher-energy X-rays are colored red, green, and blue respectively.

The Chandra image provides new insight into the nature of SN1006, which is the remnant of a so-called Type Ia supernova . This class of supernova is caused when a white dwarf pulls too much mass from a companion star and explodes, or when two white dwarfs merge and explode. Understanding Type Ia supernovas is especially important because astronomers use observations of these explosions in distant galaxies as mileposts to mark the expansion of the Universe.

Further Details on The Newly Discovered Data

pappubahry:

Jupiter’s moon Io, photographed by Voyager 2, 10 July 1979.

The end of this blog’s Io-thon follows on from yesterday’s post.  The photos used in this gif were taken with longer exposures than yesterday’s, so there is a better contrast between Io and the background.  Two volcanic eruptions are clearly visible in the top-left: I think that they are from Amirani and Maui.  There’s also an eruption on the right-hand side, but as its only lit by reflected light from Jupiter, it requires a lot of brightening to see (NASA’s photojournal shows it here).

You can also see a volcano in the south, tall enough to stay in sunlight even as the surrounding areas fall into darkness.

Yesterday I mentioned the bright spot glinting near the equator.  I asked Jason Perry (who used to write an Io blog) about it on Twitter and he said that it “looks like specular reflection off of glassy, cooled lava near Hi’iaka Patera.”  So there you go.

The rate of evolution and the ultimate fate of a star depends on its mass. (Illustration: NASA/CXC/M.Weiss)

More on stellar evolution here.

Asteroid 1998 QE2 to Sail Past Earth - Nine Times Larger Than Cruise Ship. [The orbit of asteroid 1998 QE2. Image credit: NASA/JPL-Caltech]

“On May 31, 2013, asteroid 1998 QE2 will sail serenely past Earth, getting no closer than about 3.6 million miles (5.8 million kilometers), or about 15 times the distance between Earth and the moon. And while QE2 is not of much interest to those astronomers and scientists on the lookout for hazardous asteroids, it is of interest to those who dabble in radar astronomy and have a 230-foot (70-meter) — or larger — radar telescope at their disposal.

‘Asteroid 1998 QE2 will be an outstanding radar imaging target at Goldstone and Arecibo and we expect to obtain a series of high-resolution images that could reveal a wealth of surface features,’ said radar astronomer Lance Benner, the principal investigator for the Goldstone radar observations from NASA’s Jet Propulsion Laboratory in Pasadena, Calif. ‘Whenever an asteroid approaches this closely, it provides an important scientific opportunity to study it in detail to understand its size, shape, rotation, surface features, and what they can tell us about its origin. We will also use new radar measurements of the asteroid’s distance and velocity to improve our calculation of its orbit and compute its motion farther into the future than we could otherwise.’

The closest approach of the asteroid occurs on May 31 at 1:59 p.m. Pacific (4:59 p.m. Eastern / 20:59 UTC). This is the closest approach the asteroid will make to Earth for at least the next two centuries. Asteroid 1998 QE2 was discovered on Aug. 19, 1998, by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program near Socorro, New Mexico. 

The asteroid, which is believed to be about 1.7 miles (2.7 kilometers) or nine Queen Elizabeth 2 ship-lengths in size, is not named after that 12-decked, transatlantic-crossing flagship for the Cunard Line. Instead, the name is assigned by the NASA-supported Minor Planet Center in Cambridge, Mass., which gives each newly discovered asteroid a provisional designation starting with the year of first detection, along with an alphanumeric code indicating the half-month it was discovered, and the sequence within that half-month. 

Radar images from the Goldstone antenna could resolve features on the asteroid as small as 12 feet (3.75 meters) across, even from 4 million miles away. 

‘It is tremendously exciting to see detailed images of this asteroid for the first time,’ said Benner. ‘With radar we can transform an object from a point of light into a small world with its own unique set of characteristics. In a real sense, radar imaging of near-Earth asteroids is a fundamental form of exploring a whole class of solar system objects.’”

• Continue reading the article here.
• More information about asteroids and near-Earth objects is available here, here, and via Twitter here. 
• More information about asteroid radar research is here. 
• More information about the Deep Space Network is here.

“Probably no stars will physically hit each other. There’s just so much space between the stars, but when Andromeda collides with us it’ll have a huge impact on the Milky Way. Some things will get thrown into the black hole in the middle, some stars will get ripped off and thrown away into space, so it’ll be dramatic. And the entire night sky will change.” - The Universe S1E9 Alien Galaxies

(Source: galactic-centre, via carl-sagan-cosmos)

Galaxy Collisions: Simulation vs Observations 

Images Credit: NASA, ESA; Visualization: Frank Summers (STScI); Simulation: Chris Mihos (CWRU) & Lars Hernquist (Harvard).

“What happens when two galaxies collide? Although it may take over a billion years, such titanic clashes are quite common. Since galaxies are mostly empty space, no internal stars are likely to themselves collide. Rather the gravitation of each galaxy will distort or destroy the other galaxy, and the galaxies may eventually merge to form a single larger galaxy. Expansive gas and dust clouds collide and trigger waves of star formation that complete even during the interaction process. Pictured above is a computer simulation of two large spiral galaxies colliding, interspersed with real still images taken by the Hubble Space Telescope. Our own Milky Way Galaxy has absorbed several smaller galaxies during its existence and is even projected to merge with the larger neighboring Andromeda galaxy in a few billion years.”

distant-traveller:

Hubble finds dead stars “polluted” with planetary debris

The NASA/ESA Hubble Space Telescope has found signs of Earth-like planets in an unlikely place: the atmospheres of a pair of burnt-out stars in a nearby star cluster. The white dwarf stars are being polluted by debris from asteroid-like objects falling onto them. This discovery suggests that rocky planet assembly is common in clusters, say researchers.

The stars, known as white dwarfs — small, dim remnants of stars once like the Sun — reside 150 light-years away in the Hyades star cluster, in the constellation of Taurus (The Bull). The cluster is relatively young, at only 625 million years old.

Astronomers believe that all stars formed in clusters. However, searches for planets in these clusters have not been fruitful — of the roughly 800 exoplanets known, only four are known to orbit stars in clusters. This scarcity may be due to the nature of the cluster stars, which are young and active, producing stellar flares and other outbursts that make it difficult to study them in detail.

Hubble’s spectroscopic observations identified silicon in the atmospheres of two white dwarfs, a major ingredient of the rocky material that forms Earth and other terrestrial planets in the Solar System. This silicon may have come from asteroids that were shredded by the white dwarfs’ gravity when they veered too close to the stars. The rocky debris likely formed a ring around the dead stars, which then funnelled the material inwards.

The debris detected whirling around the white dwarfs suggests that terrestrial planets formed when these stars were born. After the stars collapsed to form white dwarfs, surviving gas giant planets may have gravitationally nudged members of any leftover asteroid belts into star-grazing orbits.

Besides finding silicon in the Hyades stars’ atmospheres, Hubble also detected low levels of carbon. This is another sign of the rocky nature of the debris, as astronomers know that carbon levels should be very low in rocky, Earth-like material.

This new study suggests that asteroids less than 160 kilometres across were gravitationally torn apart by the white dwarfs’ strong tidal forces, before eventually falling onto the dead stars.

Image credit:  NASA, ESA, STScI, and G. Bacon (STScI)

pappubahry:

Mimas emerging from behind Saturn.  Photographed by Cassini, 26 October 2007.

As a matter of fact I do! I’ll share various images with you below, as well as throw out some basic information concerning Mars’ lovely moons for those who aren’t familiar.

“On Mars, Phobos would be easily visible to the naked eye at night, but would be only about one-third as large as the full Moon appears from Earth. Astronauts staring at Phobos from the surface of Mars would notice its oblong, potato-like shape and that it moves quickly against the background stars. Phobos takes only 7 hours, 39 minutes to complete one orbit of Mars. That is so fast, relative to the 24-hour-and-39-minute sol on Mars (the length of time it takes for Mars to complete one rotation), that Phobos rises in the west and sets in the east. Earth’s moon, by comparison, rises in the east and sets in the west. The smaller martian moon, Deimos, takes 30 hours, 12 minutes to complete one orbit of Mars. That orbital period is longer than a martian sol, and so Deimos rises, like most solar system moons, in the east and sets in the west.” via NASA Mars rover gallery.

The first image below, taken by NASA’s Mars Exploration Rover Spirit, shows both Deimos and Phobos, labeled for your convenience, and is titled Two Moons Passing in the Night, which was taken on the night of sol 585 (Aug. 26, 2005). [Image credit: NASA/JPL/Cornell/Texas A&M - view full sized images here.]

The second image, also taken by NASA’s Mars Exploration Rover Spirit, titled Two Moons and the Pleiades from Mars, clearly shows a labeled and unlabeled version displaying  both Phobos and Deimos, again, along with the PLeiades and Aldebaran. This image was taken on the evening of martian day, or sol, 590 (Aug. 30, 2005). [Image credit: NASA/JPL/Cornell/Texas A&M - view full sized images here.]

Next we have Phobos Viewed from Mars. “Spirit acquired the first two images with the panoramic camera on the night of sol 585 (Aug. 26, 2005). The far right image of Phobos, for comparison, was taken by the High Resolution Stereo Camera on Mars Express, a European Space Agency orbiter. The third image in this sequence was derived from the far right image by making it blurrier for comparison with the panoramic camera images to the left.”[Image credit: NASA/JPL/Cornell/Texas A&M - view full sized images here.]

Below are two images, very similar, taken by Spirit. The first, The Night Sky on Mars, which is a time-lapse composite, and was captured the evening of Spirit’s martian sol 590 (Aug. 30, 2005). The second below is named The Two Moons of Mars As Seen from Husband Hill. “Spirit took this succession of images at 150-second intervals from a perch atop “Husband Hill” in Gusev Crater on martian day, or sol, 594 (Sept. 4, 2005).” [Image credit: NASA/JPL/Cornell/Texas A&M - view full sized images here.]

Next we have some wonderful images [via the Daily Mail] of Deimos and Phobos traveling in front of the sun to create a partial solar eclipse, viewed from Mars, taken by Curiosity. The first shows Deimos and it’s small stature in comparison with our star. The second shows Phobos beginning to eclipse the Sun, as it makes it’s path across the Martian sky. 

I’ll leave you with a sped-up GIF of another eclipse, caused by Phobos, observed by Opportunity on  the afternoon of the rover’s 3,078th Martian day, or sol (Sept. 20, 2012). [via NASA]

You can view a video of Phobos eclipsing the sun on November 9, 2010 here, as captured by Opportunity. You can view more rover-captured images of both moons here, and here. I hope this answered your question sufficiently, and gives you a good place to start when looking for images of these moons taken from the Martian surface. Enjoy!

ikenbot:

New Photo Reveals ‘Ghostly’ Green Nebula in Deep Space

An amazing new photo from a telescope in Chile has captured the most detailed view yet of a green glowing blob 3,300 light-years away from Earth.

Image: This photo shows the glowing green planetary nebula IC 1295 surrounding a dim and dying star. It is located about 3300 light-years away from Earth. Credit: ESO

The new image, released today (April 10) by the European Southern Observatory, shows the planetary nebula IC 1295 like it has never been seen before. This picture, which ESO scientists dubbed “ghostly,” marks the first time the nebula has been imaged such unprecedented detail.

“It has the unusual feature of being surrounded by multiple shells that make it resemble a microorganism seen under a microscope, with many layers corresponding to the membranes of a cell,” officials from the European Southern Observatory wrote in a statement.

spacettf:

Cape York Annular Eclipse
Image Credit & Copyright: Courtesy Cameron McCarty -
MWV Observatory, Coca-Cola Space Science Center, Columbus State Univ. Eclipse Team

Explanation: This week the shadow of the New Moon fell on planet Earth, crossing Queensland’s Cape York in northern Australia … for the second time in six months. On the morning of May 10, the Moon’s apparent size was too small to completely cover the Sun though, revealing a “ring of fire” along the central path of the annular solar eclipse. Near mid-eclipse from Coen, Australia, a webcast team captured this telescopic snapshot of the annular phase. Taken with a hydrogen-alpha filter, the dramatic image finds the Moon’s silhouette just within the solar disk, and the limb of the active Sun spiked with solar prominences. Still, after hosting back-to-back solar eclipses, northern Australia will miss the next and final solar eclipse of 2013. This November, a rare hybrid eclipse will track across the North Atlantic and equatorial Africa.

Nasa Apod 11 May 2013

Airglow

by Brian Larmay

Airglow (also called nightglow) is the very weak emission of light by a planetary atmosphere. In the case of Earth’s atmosphere, this optical phenomenon causes the night sky to never be completely dark (even after the effects of starlight and diffused sunlight from the far side are removed).[**]

(Source: ikenbot)

discoverynews:

Dust to Dust: Dying Star System Spied

Stars like the sun eventually run out of hydrogen fuel and puff-up into red giants at the end of their lives — a precursor to a suicidal shedding of gas, decimating any nearby planets, eventually leaving a tiny white dwarf remnant. But a nearby star, located around 100 light-years away, has been spotted in the brief stage before the red giant phase of its death throes — and it has a dusty disk usually exclusive to young stars.