Monday, October 23, 2017

APOD - NGC 4993: The Galactic Home of an Historic Explosion

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 October 23
See Explanation.  Moving the cursor over the image will bring up an annotated version.  Clicking on the image will bring up the highest resolution version  available.

NGC 4993: The Galactic Home of an Historic Explosion
Image Credit: NASA & ESA

Explanation: That reddish dot -- it wasn't there before. It's the dot to the upper left of galaxy NGC 4993's center, do you see it? When scanning the large field of possible locations of an optical counterpart to the unprecedented gravitational wave event GW170817 in August, the appearance of this fading dot quickly became of historic importance. It pinpointed GW170817's exact location, thereby enabling humanity's major telescopes to examine the first ever electromagnetic wave counterpart to a gravitational wave event, an event giving strong evidence of being a short gamma-ray burst kilonova, the element-forming explosion that occurs after two neutron stars merge. The featured image of lenticular galaxy NGC 4993 by Hubble shows the fading dot several days after it was discovered. Analyses, continuing, include the physics of the explosion, what heavy elements formed, the similarity of the speeds of gravitational radiation and light, and calibrating a new method for determining the distance scale of our universe.

More on GW170817: Journal articles, data, graphics
Tomorrow's picture: elements of you


< | Archive | Submissions | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.


This is an automated email. If you notice any problems, just send me a note at gtracy@gmail.com. You can add and remove email addresses to this distribution list here, https://apodemail.org.Unsubscribe

No comments:

Post a Comment