By Xinhua,
Beijing : Astronomers have located the youthful remains of a stellar explosion that sent out powerful shock waves and lighted our galaxy with a blinding flash about 140 years ago.
The newly discovered remains are the youngest known supernova remnant in the Milky Way, snagging the record from the previous holder, 330-year-old Cassiopeia A.
Ever since Cass-A was discovered in the 1950s, astronomers had been searching for “missing supernovae” and their remnants. At around the same time of the Cass-A discovery, astronomers also realized two or three supernovae should light up the Milky Way every century, resulting in about 60 supernova remnants younger than 2,000 years old. To date, just 10 such remnants have been confirmed.
G1.9+0.3, the new remnant detailed in the June 10 issue of the Astrophysical Journal Letters, is the prize from the astronomers’ 50-year galactic hunt.
Supernovae are considered some of the most violent events in the universe. They are massive stars at the end of their lives, exploding with such force they generate a flash of radiation and shock waves akin to a sonic boom.
Debris thrown outward by the explosion sometimes crashes into surrounding material, resulting in a supernova remnant. This shell of hot gas and high-energy particles glows as X-rays, radio waves and other wavelengths of radiation for thousands of years.
Supernovae and their remnants are critical for creating and distributing the majority of the elements in the universe through the interstellar medium, spreading everything from cobalt to gold to radium to planets, plants, people and far beyond.
The new supernova remnant discovery involved NASA’s Chandra X-ray Observatory and National Radio Astronomy Observatory’s Very Large Array (VLA) radio telescope.
By comparing X-ray and radio images from 1985 and 2007, which show the supernova remnant is expanding, the astronomers estimated G1.9+0.3’s age. A new VLA image taken this year confirms the age and expansion rate of 35 million mph (56 million kph), which is an unprecedented expansion speed for a supernova remnant.
The astronomers estimate the centenarian is hiding out about 1,000 light-years from the galactic center, or roughly 25,000 light-years from us. A light-year is the distance light travels in one year, or about 6 trillion miles (10 trillion kilometers). So in reality, the explosion occurred about 25,140 years ago and the light reached us 140 years ago.
G1.9+0.3 most probably originated from a Type Ia supernova, the researchers say, in which a white dwarf star siphons hydrogen from a companion star and thus bulks up its mass. When the white dwarf reaches a weight that’s 1.4 times more massive than the sun, the star explodes.