Tag Archives: Astronomy

NASA Memory Lane (25)


On Feb. 5, 1974.

Mariner 10‘s Portrait of Venus
NASA – On Feb. 5, 1974, Mariner 10 took this first close-up photo of Venus.

Made using an ultraviolet filter in its imaging system, the photo has been color-enhanced to bring out Venus’s cloudy atmosphere as the human eye would see it. Venus is perpetually blanketed by a thick veil of clouds high in carbon dioxide and its surface temperature approaches 900 degrees Fahrenheit.

Launched on Nov. 3, 1973 atop an Atlas-Centaur rocket, Mariner 10 flew by Venus in 1974.

Galactic Views (57)



SPACE WATCH

Field of Stars
NASA – The Hubble Space Telescope captured a crowd of stars that looks rather like a stadium darkened before a show, lit only by the flashbulbs of the audience’s cameras. Yet the many stars of this object, known as Messier 107, are not a fleeting phenomenon, at least by human reckoning of time — these ancient stars have gleamed for many billions of years.

Messier 107 is one of more than 150 globular star clusters found around the disc of the Milky Way galaxy. These spherical collections each contain hundreds of thousands of extremely old stars and are among the oldest objects in the Milky Way. The origin of globular clusters and their impact on galactic evolution remains somewhat unclear, so astronomers continue to study them.

Messier 107 can be found in the constellation of Ophiuchus (The Serpent Bearer) and is located about 20,000 light-years from our solar system.

French astronomer Pierre Méchain first noted the object in 1782, and British astronomer William Herschel documented it independently a year later. A Canadian astronomer, Helen Sawyer Hogg, added Messier 107 to Charles Messier‘s famous astronomical catalogue in 1947.

This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. Image credit: ESA/NASA

Galactic Views (56)



SPACE WATCH

X-rays From A Young Supernova Remnant
NASA – More than fifty years ago, a supernova was discovered in M83, a spiral galaxy about 15 million light years from Earth. Astronomers have used NASA’s Chandra X-ray Observatory to make the first detection of X-rays emitted by the debris from this explosion.

Named SN 1957D because it was the fourth supernova to be discovered in the year 1957, it is one of only a few located outside of the Milky Way galaxy that is detectable, in both radio and optical wavelengths, decades after its explosion was observed. In 1981, astronomers saw the remnant of the exploded star in radio waves, and then in 1987 they detected the remnant at optical wavelengths, years after the light from the explosion itself became undetectable.

A relatively short observation — about 14 hours long — from NASA’s Chandra X-ray Observatory in 2000 and 2001 did not detect any X-rays from the remnant of SN 1957D. However, a much longer observation obtained in 2010 and 2011, totaling nearly 8 and 1/2 days of Chandra time, did reveal the presence of X-ray emission. The X-ray brightness in 2000 and 2001 was about the same as or lower than in this deep image.

This new Chandra image of M83 is one of the deepest X-ray observations ever made of a spiral galaxy beyond our own. This full-field view of the spiral galaxy shows the low, medium, and high-energy X-rays observed by Chandra in red, green, and blue respectively.

The new X-ray data from the remnant of SN 1957D provide important information about the nature of this explosion that astronomers think happened when a massive star ran out of fuel and collapsed. The distribution of X-rays with energy suggests that SN 1957D contains a neutron star, a rapidly spinning, dense star formed when the core of pre-supernova star collapsed. This neutron star, or pulsar, may be producing a cocoon of charged particles moving at close to the speed of light known as a pulsar wind nebula.

If this interpretation is confirmed, the pulsar in SN 1957D is observed at an age of 55 years, one of the youngest pulsars ever seen. The remnant of SN 1979C in the galaxy M100 contains another candidate for the youngest pulsar, but astronomers are still unsure whether there is a black hole or a pulsar at the center of SN 1979C. Image Credits: X-ray: NASA/CXC/STScI/K.Long et al., Optical: NASA/STScI

Galactic Views (55)


SPACE WATCH

The Flame Nebula

NASA – The Flame Nebula sits on the eastern hip of Orion the Hunter, a constellation most easily visible in the northern hemisphere during winter evenings. This view of the nebula was taken by WISE, NASA’s Wide-field Infrared Survey Explorer.

This image shows a vast cloud of gas and dust where new stars are being born. Three familiar nebulae are visible in the central region: the Flame Nebula, the Horsehead Nebula and NGC 2023. The Flame Nebula is the brightest and largest in the image. It is lit by a star inside it that is 20 times the mass of the sun and would be as bright to our eyes as the other stars in Orion’s belt if it weren’t for all the surrounding dust, which makes it appear 4 billion times dimmer than it actually is. Image Credit: NASA/JPL-Caltech/UCLA

Galactic Views (54)



SPACE WATCH

Black Hole Caught in a Stellar Homicide
NASA – This computer-simulated image shows gas from a star that is ripped apart by tidal forces as it falls into a black hole. Some of the gas also is being ejected at high speeds into space.

Using observations from telescopes in space and on the ground, astronomers gathered the most direct evidence yet for this violent process: a supermassive black hole shredding a star that wandered too close. NASA’s orbiting Galaxy Evolution Explorer (GALEX) and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were used to help to identify the stellar remains.

A flare in ultraviolet and optical light revealed gas falling into the black hole as well as helium-rich gas that was expelled from the system. When the star is torn apart, some of the material falls into the black hole, while the rest is ejected at high speeds. The flare and its properties provide a signature of this scenario and give unprecedented details about the stellar victim.

To completely rule out the possibility of an active nucleus flaring up in the galaxy instead of a star being torn apart, the team used NASA’s Chandra X-ray Observatory to study the hot gas. Chandra showed that the characteristics of the gas didn’t match those from an active galactic nucleus.

The galaxy where the supermassive black hole ripped apart the passing star in known as PS1-10jh and is located about 2.7 billion light years from Earth. Astronomers estimate the black hole in PS1-10jh has a mass of several million suns, which is comparable to the supermassive black hole in our own Milky Way galaxy. Image Credit: NASA, S. Gezari (The Johns Hopkins University), and J. Guillochon (University of California, Santa Cruz)