A Star-Shattering Kaboom

Cassiopeia A is  expanding debris cloud from a stellar explosion, a supernova. This picture was the result of a one million second exposure using the Chandra X-Ray Observatory.  In the false-color image, Cas A’s outer green ring, around 10 light-years across, marks the location of the expanding shock from the original supernova explosion. A structure extends beyond the ring (at about 10 o’clock), evidence that the initial explosion may have also produced energetic jets. The tiny point source near the center of Cas A is a neutron star, the collapsed remains of the stellar core. Cas A is about 10,000 light-years away, but light from the supernova explosion first reached Earth just over 300 years ago.

Image Credit: NASA

The First Recorded Supernova

This image combines data from four space telescopes to create a multi-wavelength view of all that remains of RCW 86, the oldest documented example of a supernova. Chinese astronomers witnessed the event in A. D. 185, recording a “guest star” that remained in the sky for eight months. X-ray images from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton Observatory were combined to form the blue and green colors in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova. Infrared data from NASA’s Spitzer Space Telescope and WISE, the Wide-Field Infrared Survey Explorer, shown in yellow and red, reveal dust radiating at a temperature of several hundred degrees below zero, warm by comparison to normal dust in our Milky Way galaxy.

Astronomers were able to determine from the X-ray and Infrared data that the cause of the explosion was a Type 1a supernova. In a Type 1a  supernova an otherwise-stable white dwarf or dead star is pushed beyond the brink of stability when a companion star dumps material onto it.

Scientists also used the data to solve another mystery surrounding the remnant: how it got to be so large in such a short amount of time. By blowing away wind prior to exploding, the white dwarf was able to clear out a huge cavity, a region of very low-density surrounding the system. The explosion into this cavity was able to expand much faster than it otherwise would have. This is the first time that this type of cavity has been verified around a white dwarf system prior to explosion. Scientists say the results may have significant implications for theories of white-dwarf binary systems and Type Ia supernovae.

RCW 86 is approximately 8,000 light-years away. At about 85 light-years in diameter, it occupies a region of the sky in the southern constellation of Circinus that covers slightly more of the sky than the full moon.

Image Credit: NASA / ESA

Supernova Leftovers

About 11,000 years ago, a star went supernova. The light from this event first reached Earth around A.D. 1667. There are no records of anyone noticing probably because large amounts of dust between the dying star and Earth obscured our view of the explosion.

The remnants of this supernova was finally noticed in 1947 by radio astronomers. Now known as Cassiopeia A, it is one of the brightest radio sources in the whole sky. More recently, the Wide-field Infrared Survey Explorer (WISE) was used to observe the infrared echoes from the supernova.

When WISE took this image, the blast wave had expanded out to about a distance of 21 light-years, but he flash of light from the explosion, traveling at the speed of light, had covered well over 300 light-years. The orange-colored echoes further out from the central remnant have been reflected from interstellar dust that was heated by the supernova flash centuries after the original explosion.

Image Credit: NASA / JPL / UCLA

Zooming in on a Supernova

This video zooms into the galaxy catalogued as NGC 2525. The Hubble Space Telescope captured a series of time-lapse images of a supernova in that galaxy in 2018. It appears as a very bright star located on the outer edge of one of the spiral arms. The supernova initially outshining the brightest stars in the galaxy, but it fades into obscurity during the year of observations.

Video Credit: ESA

A Shell in a Fish

supernova_shellThese thin wisps of gas are an object known as SNR 0519. The blood-red clouds are the remains from a violent explosion of a star as a supernova seen about 600 years ago. The star that exploded is known to have been a white dwarf star—a Sun-like star in the final stages of its life.

SNR 0519 is over 150 000 light-years from Earth in the southern constellation of Dorado (The Dolphinfish), a constellation that also contains most of our neighboring galaxy the Large Magellanic Cloud, a region of the sky is full of intriguing and beautiful deep sky objects. The Large Magellanic Cloud orbits the Milky Way galaxy as a satellite and is the fourth largest in our group of galaxies.

Image Credit: NASA / ESA

A Zombie Star

zombieA team of astronomers using the Hubble Space Telescope has found a star system that may have left behind a “zombie star” after an unusually weak supernova explosion. A supernova normally obliterates the exploding white dwarf, and the star effectively dies. Scientists believe this faint supernova may have left behind a surviving portion of the dwarf star—a sort of zombie star. The two inset images show before-and-after images captured by Hubble of Supernova 2012Z in the spiral galaxy NGC 1309. The white X at the top of the main image marks the location of the supernova in the galaxy.

Image Credit: NASA

A “Young” Supernova Remnant

g306_wideAstronomers estimate that a supernova explosion occurs perhaps a couple of times a century in the Milky Way. The expanding blast wave and hot stellar debris slowly dissipate over hundreds of thousands of years, eventually mixing with and becoming indistinguishable from interstellar gas. The Swift satellite uncovered the previously unknown remains of a shattered star during an X-ray survey of the galaxy’s central regions. The new object, named G306.3-0.9 after it’s coordinates in the sky,is among the youngest of the 300+ known supernova remnants in the Milky Way. Analysis indicates that G306.3–0.9 is probably less than 2,500 years old. That would make it one of the 20 youngest supernova remnants identified.

This composite image of G306.3–0.9 (the blob in the lower left) was stitched together using data from Chandra X-ray observations (blue), infrared data acquired by the Spitzer Space Telescope (red and cyan) and radio observations (purple) from the Australia Telescope Compact Array.

G306_Swift_XRTjpgThe image on the left was taken in February, 2011, using Swift’s X-ray Telescope as part of the Galactic Plane Survey. The dots in the image indicate where X-rays struck the detector. Despite this short 8.5-minute exposure, the extended circular patch of G306.3–0.9 stands out quite nicely.

Image Credits: NASA

A Cosmic Puff Ball

sn1006This cosmic puff ball is the remains of the brightest supernova in recorded history. In AD 1006, a supernova lit up the nighttime skies  and was seen by observers China, Egypt, Iraq, Italy, Japan, and Switzerland. This image was assembled from data at three different wavelength  of X-rays taken from orbit by Chandra X-ray Observatory. The debris cloud from what is now called the SN 1006 supernova remnant is about 60 light-years across. It’s the remains of a white dwarf star that was part of a binary star system. The white dwarf gradually captured ate its companion star, and the increase in mass caused a thermonuclear explosion. Because the supernova remnant is about 7,000 light-years away, that explosion actually happened 7,000 years before the light reached Earth in 1006, or in roughly 6000 BC.

Image Credit: NASA

A Supernova Remnant

The thin, red veins of energized gas in this image from the Spitzer Space Telescope are the remains of supernova HBH3. The puffy, white feature in the image is a region of star formation. In this false color image, Infrared wavelengths of 3.6 µm have been mapped to blue, and 4.5 µm to red. The white color of the star-forming region is a combination of both wavelengths. The HBH3 filaments show up only at the longer 4.5 µm wavelength.

Image Credit: NASA

Stars and Stripe

SN1006In 1006 A.D., observers from Africa to Europe to the Far East recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen in recorded times. It surpassed Venus in the night time sky, only being outshone by the moon. It was visible during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away.

About 50 years ago, radio astronomers detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred.

Today, we know that SN 1006 has a diameter of nearly 60 light-years, and is still expanding at roughly 6 million miles per hour. Even at that speed, however, it takes observations years apart to detect significant outward motion of the shock wave. This Hubble image of a delicate ribbon of gas shows a very thin section of the supernova remnant. The location of the 1006 explosion is well out of the farme to the lower left. The shock wave is moving to the upper right.

Image Credit: NASA


This animation shows a Fast-Evolving Luminous Transient. In such an explosion, a giant star “burps” out a shell of gas and dust about a year before becoming a supernova. Most of the energy from the explosion radiated as light when it runs into the previously ejected material, causing in a short, brilliant burst.

Video Credit: NASA

Detecting a Supernova

Beforem82_uvot_before_sn_largeAfterm82_uvot_after_sn_large-arrow_0These Swift Ultraviolet optical telescope images show a galaxy called M82 before and after the new supernova. The pre-explosion view combines data taken between 2007 and 2013. The view showing SN 2014J (arrow) merges three exposures taken on 22 January, 2014. Mid-ultraviolet light is shown in blue, near-UV light in green, and visible light in red. The image is slightly more than half the apparent diameter of a full moon across.

This is a Type Ia supernova, the total destruction of a white dwarf star by one of two possible scenarios. In one, the white dwarf orbits a normal star, pulls a stream of matter from it, and gains mass until it reaches a critical threshold and explodes. In the other, the blast arises when two white dwarfs in a binary system eventually spiral inward and collide.

In either case, the explosion produces a superheated shell of plasma that expands outward into space at tens of millions of miles an hour. The interactions between the shell’s size, transparency and radioactive heating control when the supernova reaches peak brightness. Astronomers expect SN 2014J to continue brightening for a few more weeks. It may be visible in binocular by early February.

M82 (aka the Cigar Galaxy) is located in the constellation Ursa Major and is a popular target for small telescopes. It’s undergoing a period of extensive star formation that makes it many times brighter than our own Milky Way galaxy.

Image Credit: NASA