Chandra Sees Stellar X-rays Exceeding Safety Limits

Image of NGC 3293
NGC 3293
Credit: X-ray: NASA/CXC/Penn State Univ./K. Getman et al.; Infrared: ESA/NASA JPL-Caltech/Herschel Space Observatory/JPL/IPAC; NASA JPL-Caltech/SSC/Spitzer Space Telescope; Optical: MPG/ESO/G. Beccari;

Astronomers have made the most extensive study yet of how magnetically active stars are when they are young. This gives scientists a window into how X-rays from stars like the Sun, but billions of years younger, could partially or completely evaporate the atmospheres of planets orbiting them.

Many stars begin their lives in “open clusters,” loosely packed groups of stars with up to a few thousand members, all formed roughly at the same time. This makes open clusters valuable for astronomers investigating the evolution of stars and planets, because they allow the study of many stars of similar ages forged in the same environment.

A team of astronomers led by Konstantin Getman of Penn State University studied a sample of over 6,000 stars in 10 different open clusters with ages between 7 million and 25 million years. One of the goals of this study was to learn how the magnetic activity levels of stars like our Sun change during the first tens of millions of years after they form. Getman and his colleagues used NASA’s Chandra X-ray Observatory for this study because stars that have more activity linked to magnetic fields are brighter in X-rays.

Astronomers See Stellar Self-Control in Action

X-ray and Infrared image of RCW 36
RCW 36
Credit: X-ray: NASA/CXC/Ames Research Center/L. Bonne et al.; Infrared: ESA/NASA.JPL-Caltech/Herschel Space Observatory/JPL/IPAC

Many factors can limit the size of a group, including external ones that members have no control over. Astronomers have found that groups of stars in certain environments, however, can regulate themselves.

A new study has revealed stars in a cluster having “self-control,” meaning that they allow only a limited number of stars to grow before the biggest and brightest members expel most of the gas from the system. This process should drastically slow down the birth of new stars, which would better align with astronomers’ predictions for how quickly stars form in clusters.

This study combines data from several telescopes including NASA's Chandra X-ray Observatory, NASA's now-retired Stratospheric Observatory for Infrared Astronomy (SOFIA), the APEX (the Atacama Pathfinder EXperiment) telescope, and ESA’s (European Space Agency’s) retired Herschel telescope.

'Listen' to the Light Echoes From a Black Hole

Credit: X-ray: Chandra: NASA/CXC/U.Wisc-Madison/S. Heinz et al.; Swift: NASA/Swift/Univ. of Leicester/A. Beardmore; Optical/IR: PanSTARRS; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

One of the surprising features of black holes is that although light (such as radio, visible, and X-rays) cannot escape from them, surrounding material can produce intense bursts of electromagnetic radiation. As they travel outward, these blasts of light can bounce off clouds of gas and dust in space, similar to how light beams from a car’s headlight will scatter off fog.

A new sonification turns these “light echoes” from the black hole called V404 Cygni into sound. Located about 7,800 light-years from Earth, V404 Cygni is a system that contains a black hole, with a mass between five and 10 times the Sun’s, that is pulling material from a companion star in orbit around it. The material is funneled into a disk that encircles the stellar-mass black hole.

Planets Can Be Anti-Aging Formula for Stars

Hot Jupiters
Hot Jupiters
Credit: Illustration: NASA/CXC/M.Weiss. X-ray: NASA/CXC/Potsdam Univ./N. Ilic et al.

An artist’s illustration shows a gas giant planet (lower right) closely orbiting its host star (left), with another star in the distance (upper right). The two stars are themselves in orbit with each other. As explained in our latest press release, a team of scientists used NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton to test whether such exoplanets (known as “hot Jupiters”) affect their host star in comparison to the star that does not have one. The results show that these exoplanets can make their host star act younger than it is by causing the star to spin more quickly than it would without such a planet.

The double-star (or “binary”) system in the illustration is one of dozens that astronomers studied using Chandra and XMM-Newton to look for the effects of hot Jupiters on their host stars. A hot Jupiter can potentially influence its host star by tidal forces, causing the star to spin more quickly than if it did not have such a planet. This more rapid rotation can make the host star more active and produce more X-rays, making it appear younger than it really is.

NASA's IXPE Helps Unlock the Secrets of Famous Exploded Star

X-ray and optical of Cassiopeia A
Cassiopeia A
Credit: X-ray: Chandra: NASA/CXC/SAO, IXPE: NASA/MSFC/J. Vink et al.; Optical: NASA/STScI

For the first time, astronomers have measured and mapped polarized X-rays from the remains of an exploded star, using NASA’s Imaging X-ray Polarimetry Explorer (IXPE). The findings, which come from observations of a stellar remnant called Cassiopeia A, shed new light on the nature of young supernova remnants, which accelerate particles close to the speed of light.

Launched on Dec. 9, 2021, IXPE, a collaboration between NASA and the Italian Space Agency, is the first satellite that can measure the polarization of X-ray light with this level of sensitivity and clarity.

All forms of light — from radio waves to gamma rays — can be polarized. Unlike the polarized sunglasses we use to cut the glare from sunlight bouncing off a wet road or windshield, IXPE’s detectors maps the tracks of incoming X-ray light. Scientists can use these individual track records to figure out the polarization, which tells the story of what the X-rays went through.

Cassiopeia A (Cas A for short) was the first object IXPE observed after it began collecting data. One of the reasons Cas A was selected is that its shock waves — like a sonic boom generated by a jet — are some of the fastest in the Milky Way. The shock waves were generated by the supernova explosion that destroyed a massive star after it collapsed. Light from the blast swept past Earth more than three hundred years ago.

NASA's Chandra Finds Galaxy Cluster Collision on a "WHIM"

Abell 98
Credit: X-ray: NASA/CXC/CfA/A. Sarkar; Optical: NSF/NOIRLab/WIYN

This image features Abell 98, a system of galaxy clusters that includes a pair in the early stages of a collision. Astronomers have used data from NASA’s Chandra X-ray Observatory (shown as blue and purple with optical data from the WIYN telescope on Kitt Peak in Arizona appearing white and red) to identify key structures and look for “missing” matter in the Universe.

Chandra Adds X-ray Vision to Webb Images

In the summer of 2022, NASA's James Webb Space Telescope released images from some of its earliest observations with the newly commissioned telescope. Almost instantaneously, these stunning images landed everywhere from the front pages of news outlets to larger-than-life displays in Times Square.

Webb, however, will not pursue its exploration of the universe on its own. It is designed to work in concert with NASA's many other telescopes as well as facilities both in space and on the ground. These new versions of Webb’s first images combine its infrared data with X-rays collected by NASA’s Chandra X-ray Observatory, underscoring how the power of any of these telescopes is only enhanced when joined with others.

New "Realities" of The Cat’s Eye Nebula

There are some objects in space that are so photogenic that their images get circulated far beyond the regular confines of the astronomical community. NASA’s Hubble Space Telescope helped bring attention to the Cat’s Eye when its striking first image was released in 1994. Since then, Hubble has returned to the Cat’s Eye while other telescopes that detect different kinds of light — including NASA’s Chandra X-ray Observatory — have also observed it.

X-ray and optical image of the Cat's Eye Nebula

Cat's Eye Nebula (NGC 6543)
Credit: X-ray: NASA/CXC/RIT/J.Kastner et al.; Optical: NASA/STScI

What is the Cat’s Eye? It is officially categorized as a planetary nebula, a misleading label that stuck from its origins in the 19th century. Because these objects look like planets through small telescopes, astronomers named them “planetary nebulas”.

Today, astronomers know these objects have little to do with planets. They are, in fact, a stage toward the end life of stars like our Sun. After the star uses most of its fuel, it puffs off its outer layers while the core shrinks to a stellar nub. Winds and radiation from the star’s core — known as a white dwarf — push and energize the discarded material, sometimes creating spectacular structures. The Cat’s Eye, also known more formally as NGC 6543 and apparently the name of a Stephen King movie from 1985, is a planetary nebula about 3,200 light years from the Earth in the direction of the Draco constellation.

Setting the Clock on a Stellar Explosion

Image of SNR 0519-69.0
Supernova Remnant 0519-69.0
Credit: X-ray: NASA/CXC/GSFC/B. J. Williams et al.; Optical: NASA/ESA/STScI

While astronomers have seen the debris from scores of exploded stars in the Milky Way and nearby galaxies, it is often difficult to determine the timeline of the star’s demise. By studying the spectacular remains of a supernova in a neighboring galaxy using NASA telescopes, a team of astronomers has found enough clues to help wind back the clock.

The supernova remnant called SNR 0519-69.0 (SNR 0519 for short) is the debris from an explosion of a white dwarf star. After reaching a critical mass, either by pulling matter from a companion star or merging with another white dwarf, the star underwent a thermonuclear explosion and was destroyed. Scientists use this type of supernova, called a Type Ia, for a wide range of scientific studies ranging from studies of thermonuclear explosions to measuring distances to galaxies across billions of light-years.

50 Years Ago, NASA’s Copernicus Set the Bar for Space Astronomy

With closed-captions (at YouTube)
This vintage segment on Copernicus comes from a 1973 edition of “The Science Report,” a long-running film series produced by the U.S. Information Agency. Credit: National Archives (306-SR-138B)

The following blog post is a special feature on the history of astrophysics and space science written by Francis Reddy, a public affairs specialist at NASA’s Goddard Space Flight Center. There is a brief summary of how X-ray astronomy, including the Chandra X-ray Observatory, and practically every other branch of astrophysics benefited from humanity’s success at launching objects into orbit. The original post is available on the NASA portal.

At 6:28 a.m. EDT on Aug. 21, 1972, NASA’s Copernicus satellite, the heaviest and most complex space telescope of its time, lit up the sky as it ascended into orbit from Launch Complex 36B at Cape Canaveral Air Force Station, Florida.

Initially known as Orbiting Astronomical Observatory (OAO) C, it became OAO 3 once in orbit in the fashion of the time. But it was also renamed to honor the upcoming 500th anniversary of the birth of Nicolaus Copernicus (1473 – 1543). The Polish astronomer formulated a model of the solar system with the Sun in the central position instead of Earth, breaking with 1,300 years of tradition and triggering a scientific revolution.

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