stellar flare

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This is the audio log of Communications Officer Doug Eiffel. I am speaking from the comms room of the U.S.S. Hephaestus Station. Welcome to day 448 of our orbit around red dwarf star Wolf 359. Today’s weather report: pretty nominal. Surface temperature’s averaging at about… Oh, a crisp 4,500 degrees Fahrenheit. Instruments are picking up less than 10% chance of stellar flares. Just another happy, sunny day out here… seven and a half light years away from Earth.

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Astroquizzical: Could Black Holes Be The Engines Of New Galaxies?

“Observing techniques developed, and it became clear that these quasars were indeed in the centers of galaxies, but the galaxies were incredibly faint relative to the brightness of the quasar (hence why we couldn’t spot them before). A number of theories were put forth: merging neutron stars, interacting stellar mass black holes, flares from collisions, etc. But thanks to more advanced techniques, we determined the light from quasars to be produced by the central black hole of these faint galaxies, dramatically outshining the rest of the galaxy.”

When young galaxies are first formed, they’re accompanied by tremendous bursts of star formation, giving rise to billions of new stars within just a few million years. Yet how these galaxies first form in the initial stages is very much an open question. In addition, pretty much every large galaxy we find — even in the extremely young Universe — has a supermassive black hole at its center. But these black holes aren’t the engines of newly formed galaxies, it’s the other way around!

Jillian Scudder has the story on this edition of Astroquizzical.

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Solar Flares and CME’s: Coronal Mass Ejections 

A Solar Flare is a sudden flash of brightness observed over the Sun’s surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy. They are often, but not always, followed by a colossal coronal mass ejection. The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach Earth a day or two after the event. The term is also used to refer to similar phenomena in other stars, where the term stellar flare applies.

A Coronal Mass Ejection (CME) is a massive burst of gas and magnetic field arising from the solar corona and being released into the solar wind, as observed in a coronagraph. Coronal mass ejections are often associated with other forms of solar activity, most notably solar flares or filament eruptions, but a broadly accepted theoretical understanding of these relationships has not been established. 

CMEs most often originate from active regions on the Sun’s surface, such as groupings of sunspots associated with frequent flares. Near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days.

Giffed by: rudescience  From: This video by nasa

Black hole caught in a stellar homicide

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)

Stellar Flare Hits HD 189733b

This artist’s impression shows exoplanet HD 189733b, as it passes in front of its parent star, called HD 189733A.

Hubble’s instruments observed the system in 2010, and in 2011 following a large flare from the star (depicted in the image). Following the flare, Hubble observed the planet’s atmosphere evaporating at a rate of over 1000 tonnes per second.

In this picture, the surface of the star, which is around 80% the mass of the Sun, is based on observations of the Sun from the Solar Dynamics Observatory.