Black Hole Awakens After 26 Years

schwit1 writes: For the first time since 1989, the black hole in V404 Cygni, a system comprising a black hole and a star, has reawakened, suddenly emitting high energy outbursts beginning on June 15. The outbursts are probably occurring because the black hole is gobbling up material that has fallen into it. While the 1989 outburst helped astronomers gain their first understand of the behavior of a black hole in a star system, this outburst will help them understand how such systems evolve and change over time. The European Space Agency (ESA) reports: "First signs of renewed activity in V404 Cygni were spotted by the Burst Alert Telescope on NASA's Swift satellite, detecting a sudden burst of gamma rays, and then triggering observations with its X-ray telescope. Soon after, MAXI (Monitor of All-sky X-ray Image), part of the Japanese Experiment Module on the International Space Station, observed an X-ray flare from the same patch of the sky. These first detections triggered a massive campaign of observations from ground-based telescopes and from space-based observatories, to monitor V404 Cygni at many different wavelengths across the electromagnetic spectrum."

Comments

Watch a movie of V404 Cyg in the optical

[StupendousMan]

I've been using our university's observatory to take images of V404 Cyg for the past week. On Jun 23/24, the star underwent a particularly crazy series of variations: over a period of six hours, it fell to just 5 percent of its initial brightness, then recovered almost to its starting point.

I made an animated GIF showing the star's changes over this period. You can see it on my observing log for the the night:

http://spiff.rit.edu/richmond/...

That page also includes my full dataset, and pointers to additional reading.

The star is currently bright enough -- mag 11-14 -- to be studied easily with small telescopes. Anyone interested in joining the effort should start with the American Association of Variable Star Observers (AAVSO) -- go to their campaign page at

http://www.aavso.org/aavso-ale...

Re:I hate the term "awakens"

[CBM]

Actually the term is appropriate. Gravity doesn't disappear, but material can orbit the black hole in an accretion disk, in a dormant state. When enough material builds up in the disk, accretion flow to the black hole can activate. It's called an accretion disk instability. In the astronomy business we would say the black hole has become active, or is having a transient outburst, but awaken is fine for public consumption.