Space news (galaxy formation: galaxy tails; the largest ever) – 680 million light-years from Earth toward the constellation Hercules –
The ghostly blue, diffuse ribbon of hot gas seen trailing behind galaxy CGCG254-021 in the upper right of this composite image is the longest, largest galaxy tail observed during the human journey to the beginning of space and time. This stunning view was made using X-ray data (blue) collected by NASA’s Chandra Observatory and data (yellow) from the Isaac Newton Group of Telescopes.
Galaxy tails are wispy ribbons of hot gas stripped from a galaxy as it travels through an immense cloud of hot intergalactic gas. In the case of galaxy CGCG254-021, a tail of hot gas estimated at over 250,000 light-years in length, and around 10 million degrees Centigrade, which is half the estimated temperature of the intergalactic gas cloud.
Astronomers think CGCG254-021’s tail was stripped from the galaxy as it moved through hot gas in galaxy cluster Zwicky 8338. The pressure exerted by this rapid motion stripped gas away from the galaxy, creating the ghostly blue ribbon of hot gas observed. A ribbon astronomers think could be completely free of the galaxy, considering the distance between the two as seen in this image.
Astronomers have been studying interactions between the ribbon and galaxy CGCG254-021 by examining the characteristics and properties of the galaxy and its ghostly tail. They noted it has a brighter spot they call its head with a tail of diffuse x-ray emission trailing behind. This could indicate the gas in the head in cooler and richer in elements heavier than helium compared to the rest of the ribbon. There’s also a hint of a bow shock at the head of the tail with the galaxy at the front.
Additional observations by researchers at infrared wavelengths also show galaxy CGCG254-021 has more mass than any other galaxy in galaxy cluster Zwicky 8338. Using the data obtained and models of the evolution of galaxies astrophysicists predicted it recently had the highest rate of new star formation in the cluster. However, they can find no evidence of new stars recently forming within the galaxy. They think this lack of new stars is due to the stripping of gas as it traveled through galaxy cluster Zwicky 8338.
Astrophysicists plan on additional observations of galaxy CGCG254-021 and Zwicky 8383 in the future using Chandra, the Newton Group of telescopes, and other assets. They hope to fill in the blanks on how it obtained the largest galaxy tail recorded during the human journey to the beginning of space and time. To learn the story of how this galaxy got its ghostly blue tail.
Hypernova SN 2006gy was over a hundred times brighter than a typical supernova
Space news (astrophysics: hypernovae; one of the brightest ever, SN 2006gy) – 240 million light-years toward the constellation Perseus in galaxy NGC 1260 –
It all started in September of 2006 when a fourth-year University of Texas graduate student astronomer working for the Palomar Transient Factory’s (PTF) luminous supernova program Robert Quimby discovered the brightest celestial event up to this date. An exploding star over 100 times brighter than a normal supernova and shining brighter than the core of its host galaxy NGC 1260.
“This was a truly monstrous explosion, a hundred times more energetic than a typical supernova,” said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas at Austin. “That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We’ve never seen that before.”
Teams of astronomers working with the Katzman Automatic Imaging Telescope at the Lick Observatory on Mt. Hamilton in California and M.W. Keck Observatory near the summit of Mauna Kea on the island of Hawaii immediately began observing the event designated supernova SN 2006gy. Analysis of data showed it occurred over 240 million light-years away in galaxy NGC 1260 and took 70 days to reach maximum brightness. Staying brighter than any previously recorded event for over three months, SN 2006gy was still as bright as a normal supernova eight months later.
“Of all exploding stars ever observed, this was the king,” said Alex Filippenko, leader of the ground-based observations at the Lick Observatory at Mt. Hamilton, Calif., and the Keck Observatory in Mauna Kea, Hawaii. “We were astonished to see how bright it got, and how long it lasted.”
Astronomers were reasonably sure at this point the progenitor of supernova SN 2006gy was one of the largest, most massive types of stars ever to exist. But they needed to rule out the most likely alternative explanation for the event. The possibility a white dwarf star with a mass slightly higher than Sol went supernova in a dense, hydrogen-rich environment.
Another team of astronomers using the Chandra X-ray Observatory went to work at this point to rule this possibility out of their equations. If this was the case, they knew X-ray emission from the event should be at least 1,000 times more luminous than the readings they were getting.
“This provides strong evidence that SN 2006gy was, in fact, the death of an extremely massive star,” said Dave Pooley of the University of California at Berkeley, who led the Chandra observations.
The progenitor star for SN 2006gy is thought to have ejected a large volume of mass before the hypernova event occurred. This is similar to events observed by astronomers in the case of Eta Carinae, a nearby supermassive star they’re watching closely for signs of an impending supernova. Only 7,500 light-years toward the constellation Carina, compared to 240 million for galaxy NGC 1260, this star going supernova would be the celestial event of the century on Earth. It would be bright enough to see in the daylight sky.
“We don’t know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case,” said Mario Livio of the Space Telescope Science Institute in Baltimore, who was not involved in the research. “Eta Carinae’s explosion could be the best star-show in the history of modern civilization.”
So many questions
Astronomers think in the case of hypernova SN 2006gy things might have taken a slightly different pathway than previously recorded supernovae. Some scientists think the massive star that exploded could be much more like the supermassive stars that existed during the early moments of the cosmos. Supermassive stars that exploded in supernovae and spread the elements of creation across the cosmos, rather than collapsing to a black hole as theorized.
“In terms of the effect on the early universe, there’s a huge difference between these two possibilities,” said Smith. “One [sprinkles] the galaxy with large quantities of newly made elements and the other locks them up forever in a black hole.”
Why would these supermassive stars be different than other huge stars observed in the Milky Way? The human search for answers to these and other mysterious questions before us continues as we journey backward to the beginning of space and time.
We’ll update you with any additional data astronomers come across as the journey continues. Until next time, keep dreaming of the possibilities.
Editor and Chief
The Human Journey to the beginning of space and time.
Revealing the youthful glow of blue star clusters and a dusty core hidden from view
Space news (astrophysics: giant elliptical galaxies; Centaurus A) – 11 million light-years from Earth toward the constellation Centaurus (NGC 5128) –
The closest galaxy to Earth with an active nucleus containing a supermassive black hole that ejects jets of high-speed, extremely energetic particles into space, the giant elliptical island universe Centaurus A’s (NGC 5128) a nearby laboratory in which astronomers test present theories.
The stunning Hubble Space Telescope image of Centaurus A (above) reveals a scene resembling cosmic clouds on a stormy day. Dark lanes of gas and dust crisscross its warped disk, revealing the youthful glow of blue star clusters, and red patches indicating shockwaves from a recent merger with a spiral galaxy. Shockwaves that cause hydrogen gas clouds to contract, starting the process of new star formation.
The startling composite image of Centaurus A above combines X-ray data from NASA’s Chandra Observatory, optical data from the European Southern Observatory’s Very Large Telescope, and the National Radio Astronomy Observatory’s Very Large Array. The core of NGC 5128 is a mess of gas, dust, and stars in visible light, but X-rays and radio waves reveal a stunning jet of high-speed, extremely energetic particles emanating from its active nucleus.
What could power such an event?
The power source for the relativistic jets observed streaming from the active galactic nucleus of Centaurus A’s a supermassive black hole with the estimated mass of over 10 million suns. Beaming out from the galactic nucleus toward the upper left, the high-speed jet travels nearly 13,000 light-years, while a shorter jet shoots from the core in the opposing direction. Astronomers think the source of the chaos in active galaxy Centaurus A’s the noted collision with a spiral galaxy about 100 million years ago.
The amazing high-energy, extremely-fast, 30,000 light-year-long particle jet is the most striking feature in the false-color X-ray image taken by the Chandra Observatory. Beaming upward toward the left corner of the image, the relativistic jet seems to blast from the core of Centaurus A. A core containing an active, monster black hole pulling nearby matter into the center of its gravity well. An unknown realm mankind dreams about visiting one day.
You can learn more about supermassive black holes here.