In the Center of the Lagoon


lagooncenter_hstschmidt_960The Lagoon Nebula, also known as M8, lies about 5,000 light years distant toward the constellation of Sagittarius. Its center is a maelstrom of star formation. The two long funnel-shaped clouds near the center of the picture are each roughly half a light-year long. They were formed by extreme stellar winds and intense energetic starlight. An exceptionally bright nearby star, Herschel 36, dominates the area. Walls of dust hide and redden other hot young stars. This picture spans about 5 light years and combines several images taken by the Hubble Space Telescope.

Image Credit: Hubble Legacy Archive / NASA / ESA
Processing & License: Judy Schmidt

A Nearby Supernova


m82_supernovaThis past January, astronomers witnessed a supernova soon after it exploded in the galaxy known as Messier 82 or M82. Telescopes around the world and in orbit turned their attention to study this newly exploded star, including the Chandra X-ray Observatory. It seems that this supernova, cataloged as SN 2014J, belongs to a class of explosions called “Type Ia” supernovas. The predominant theory is that all Type Ia supernovas involve the detonation of a white dwarf, but there is a question as to whether the fuse on the explosion is lit when the white dwarf pulls too much material from a companion star like the Sun or when two white dwarf stars merge.

This image contains data from Chandra with low, medium, and high-energy X-rays shown in red, green, and blue respectively. The boxes in the bottom of the image show close-up views of the region around the supernova in data taken prior to the explosion (left), as well as data gathered in February after the supernova exploded (right). The lack of the detection of X-rays detected by Chandra is an important clue for astronomers looking for the exact mechanism causing the supernova.

The lack of X-rays suggests that the region around the site of the supernova explosion is relatively devoid of matter. That’s a critical clue to the origin of the explosion. If the white dwarf exploded because it had been steadily collecting matter from a companion star prior to going nova, the mass transfer process would not be 100% efficient, and the white dwarf would be immersed in a cloud of gas. If a significant amount of material were surrounding the doomed star, the blast wave generated by the supernova would have struck it by the time of the Chandra observation, producing a bright X-ray source. The lack of x-rays shows that the region around SN 2014J is exceptionally clean.

One possible explanation is that the explosion was caused by the merger of two white dwarf stars. In that case there might have been little mass transfer and pollution of the environment before the explosion. Another possible explanation is that several smaller eruptions on the surface of the white dwarf cleared the region prior to the supernova. Further observations made over the next months could show on the amount of gas in a larger volume and help decide between these and other scenarios.

Image Credit: NASA

Rosetta’s Closing In


esa_rosetta_osirisnac_130806_aThis close up image focused on a smooth region on the “base” of the “body” section of comet 67P/Churyumov-Gerasimenko was taken by Rosetta’s Onboard Scientific Imaging System (OSIRIS) on 6 August, 2014. The picture shows a range of features, including boulders, craters and steep cliffs. It was taken from a distance of 130 km. The resolution is about 2.5 m/pixel.

Image Credit: ESA

A Zombie Star


zombieA team of astronomers using the Hubble Space Telescope has found a star system that may have left behind a “zombie star” after an unusually weak supernova explosion. A supernova normally obliterates the exploding white dwarf, and the star effectively dies. Scientists believe this faint supernova may have left behind a surviving portion of the dwarf star—a sort of zombie star. The two inset images show before-and-after images captured by Hubble of Supernova 2012Z in the spiral galaxy NGC 1309. The white X at the top of the main image marks the location of the supernova in the galaxy.

Image Credit: NASA

Rosetta’s Rendezvous


If all goes well, by the time this post goes up, the Rosetta spacecraft will have begun it’s rendezvous with Comet 67P/Churyumov-Gerasimenko early this morning. Rosetta will carry out a complex series of maneuvers to reduce bring the spacecraft to within about 100 km of the comet and then down to 25 to 30 km. The spacecraft will begin mapping the comet from that distance to find a landing site for the mission’s Philae lander. In November, Rosetta will come to within just 2.5 km of the comet’s nucleus to deploy the lander. The objects in the animation is not to scale; Rosetta’s solar arrays span 32 m, and the comet is approximately 4 km wide.

Video Credit: ESA

Knots of Wonder


Video Credit: NASA / STSci

This Isn’t the Moon


It’s Mercury. The MESSENGER spacecraft captured images used to make this video during a flyover of the planet’s north pole on 8 June, 2014. The images were taken once per second while the spacecraft was at altitudes ranging from 115 to 165 km, traveling at a speed of 3.7 km/s relative to the surface. The frame rate has been sped up by a factor of seven for ease of viewing. The images have resolutions ranging from 21 to 45 m/pixel.

Video Credit: NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

BTW, MESSENGER was launched ten years ago today.