HEAPOW: How to Hide a Supernova (2023 Feb 20)

[bystander]

How to Hide a Supernova

It seems hard to hide a supernova, the complete explosive destruction of a star - but evidently that's happened. In 2008 astronomers, using the Chandra X-ray Observatory, found a glowing mass of X-ray emitting gas near the center of the Milky Way. Optical images showed absolutely nothing out of the ordinary, since the remnant is hidden behind a large mass of dust - but X-rays (and radio waves emitted by the remnant) penetrate the dust to reveal the explosion. Oddly enough, as seen from earth, the supernova must have occurred in 1900 (as seen from earth), but was unnoticed by earthly observers it the most recent Milky Way supernova. How many more remain to be discovered? New observing faciliites that can scan large regions of the sky in the optical (like the Zwicky Transient Facility, the Vera C. Rubin Observatory, and the Nancy Grace Roman Space Telescope) along with existing high energy observatories like the Fermi Gamma-ray Space Telescope, the Swift Burst Alert Telescope, and others should help ensure we don't miss any new explosions in our Galaxy.

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Author: Dr. Michael F. Corcoran

[bystander]

G1.9+0.3: The Remarkable Remains of a Recent Supernova
NASA | MSFC | SAO | Chandra X-ray Observatory | 2013 Jun 26

Credit: X-ray (NASA/CXC/NCSU/K.Borkowski et al.); Optical (DSS)

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Astronomers estimate that a star explodes as a supernova in our Galaxy, on average, about twice per century. In 2008, a team of scientists announced they discovered the remains of a supernova that is the most recent, in Earth's time frame, known to have occurred in the Milky Way.

The explosion would have been visible from Earth a little more than a hundred years ago if it had not been heavily obscured by dust and gas. Its likely location is about 28,000 light years from Earth near the center of the Milky Way. A long observation equivalent to more than 11 days of observations of its debris field, now known as the supernova remnant G1.9+0.3, with NASA's Chandra X-ray Observatory is providing new details about this important event.

The source of G1.9+0.3 was most likely a white dwarf star that underwent a thermonuclear detonation and was destroyed after merging with another white dwarf, or pulling material from an orbiting companion star. This is a particular class of supernova explosions (known as Type Ia) that are used as distance indicators in cosmology because they are so consistent in brightness and incredibly luminous.

The explosion ejected stellar debris at high velocities, creating the supernova remnant that is seen today by Chandra and other telescopes. This new image is a composite from Chandra where low-energy X-rays are red, intermediate energies are green and higher-energy ones are blue. Also shown are optical data from the Digitized Sky Survey, with appearing stars in white. The new Chandra data, obtained in 2011, reveal that G1.9+0.3 has several remarkable properties. ...

Supernova Ejecta in the Youngest Galactic Supernova Remnant G1.9+0.3 ~ Kazimierz J. Borkowski et al

• Astrophysical Journal Letters 771(1):L9 (2021 Jul 01) DOI: 10.1088/2041-8205/771/1/L9
• arXiv > astro-ph > arXiv:1305.7399 > 31 May 2013

[bystander]

Under a Bushel of Dust
NASA | GSFC | HEASARC | HEAPOW | 2008 May 19

G1.9+0.3: Discovery of Most Recent Supernova in Our Galaxy
NASA | MSFC | SAO | Chandra X-ray Observatory | 2008 May 14

The Youngest Galactic Supernova Remnant: G1.9+0.3 ~ Stephen P. Reynolds et al

• Astrophysical Journal 680(1):L41 (2008 Jun 10) DOI: 10.1086/589570
• arXiv > astro-ph > arXiv:0803.1487 > 10 Mar 2008 (v1), 23 Apr 2008 (v2)

[Ann]

From what I've known, it's not possible to hide a supernova. A supernova is a powerful and intense astronomical event that can be seen from great distances. It is caused by the explosion of a massive star at the end of its life cycle, and it releases an enormous amount of energy and light into space.

Yes, it is possible to hide a supernova, at least in the Milky Way, at least from our point of view. We can't see the central parts of our galaxy with optical instruments, because they are hidden behind light-years of dust.

The supernova that was hidden exploded in 1985. Our ability to detect supernovas has improved by leaps and bounds since then.

Consider supernova 1987A. It was called "1987A" because it was the first supernova detected that year, in 1987. But it was detected on February 23, 1987. Not a single supernova had been detected in January and most February that year!

For comparison, 473 supernovas have been reported and confirmed in 2023, and another 4430 have been reported but not confirmed.

Ann