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By NASA
X-ray: NASA/CXC/Technion/N. Keshet et al.; Illustration: NASA/CXC/SAO/M. Weiss People often think about archaeology happening deep in jungles or inside ancient pyramids. However, a team of astronomers has shown that they can use stars and the remains they leave behind to conduct a special kind of archaeology in space.
Mining data from NASA’s Chandra X-ray Observatory, the team of astronomers studied the relics that one star left behind after it exploded. This “supernova archaeology” uncovered important clues about a star that self-destructed – probably more than a million years ago.
Today, the system called GRO J1655-40 contains a black hole with nearly seven times the mass of the Sun and a star with about half as much mass. However, this was not always the case.
Originally GRO J1655-40 had two shining stars. The more massive of the two stars, however, burned through all of its nuclear fuel and then exploded in what astronomers call a supernova. The debris from the destroyed star then rained onto the companion star in orbit around it, as shown in the artist’s concept.
This artist’s impression shows the effects of the collapse and supernova explosion of a massive star. A black hole (right) was formed in the collapse and debris from the supernova explosion is raining down onto a companion star (left), polluting its atmosphere.CXC/SAO/M. Weiss With its outer layers expelled, including some striking its neighbor, the rest of the exploded star collapsed onto itself and formed the black hole that exists today. The separation between the black hole and its companion would have shrunk over time because of energy being lost from the system, mainly through the production of gravitational waves. When the separation became small enough, the black hole, with its strong gravitational pull, began pulling matter from its companion, wrenching back some of the material its exploded parent star originally deposited.
While most of this material sank into the black hole, a small amount of it fell into a disk that orbits around the black hole. Through the effects of powerful magnetic fields and friction in the disk, material is being sent out into interstellar space in the form of powerful winds.
This is where the X-ray archaeological hunt enters the story. Astronomers used Chandra to observe the GRO J1655-40 system in 2005 when it was particularly bright in X-rays. Chandra detected signatures of individual elements found in the black hole’s winds by getting detailed spectra – giving X-ray brightness at different wavelengths – embedded in the X-ray light. Some of these elements are highlighted in the spectrum shown in the inset.
The team of astronomers digging through the Chandra data were able to reconstruct key physical characteristics of the star that exploded from the clues imprinted in the X-ray light by comparing the spectra with computer models of stars that explode as supernovae. They discovered that, based on the amounts of 18 different elements in the wind, the long-gone star destroyed in the supernova was about 25 times the mass of the Sun, and was much richer in elements heavier than helium in comparison with the Sun.
This analysis paves the way for more supernova archaeology studies using other outbursts of double star systems.
A paper describing these results titled “Supernova Archaeology with X-Ray Binary Winds: The Case of GRO J1655−40” was published in The Astrophysical Journal in May 2024. The authors of this study are Noa Keshet (Technion — Israel Institute of Technology), Ehud Behar (Technion), and Timothy Kallman (NASA’s Goddard Space Flight Center).
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory.
Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features an artist’s rendering of a supernova explosion, inset with a spectrum graph.
The artist’s illustration features a star and a black hole in a system called GRO J1655-40. Here, the black hole is represented by a black sphere to our upper right of center. The star is represented by a bright yellow sphere to our lower left of center. In this illustration, the artist captures the immensely powerful supernova as a black hole is created from the collapse of a massive star, with an intense burst of blurred beams radiating from the black sphere. The blurred beams of red, orange, and yellow light show debris from the supernova streaking across the entire image in rippling waves. These beams rain debris on the bright yellow star.
When astronomers used the Chandra X-ray Observatory to observe the system in 2005, they detected signatures of individual elements embedded in the X-ray light. Some of those elements are highlighted in the spectrum graph shown in the inset, positioned at our upper lefthand corner.
The graph’s vertical axis, on our left, indicates X-ray brightness from 0.0 up to 0.7 in intensity units. The horizontal axis, at the bottom of the graph, indicates Wavelength from 6 to 12 in units of Angstroms. On the graph, a tight zigzagging line begins near the top of the vertical axis, and slopes down toward the far end of the horizontal axis. The sharp dips show wavelengths where the light has been absorbed by different elements, decreasing the X-ray brightness. Some of the elements causing these dips have been labeled, including Silicon, Magnesium, Iron, Nickel, Neon, and Cobalt.
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
lane.e.figueroa@nasa.gov
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By European Space Agency
Video: 00:00:43 Aside from sunlight, the Sun sends out a gusty stream of particles called the solar wind. The ESA-led Solar Orbiter mission is the first to capture on camera this wind flying out from the Sun in a twisting, whirling motion. The solar wind particles spiral outwards as if caught in a cyclone that extends millions of kilometres from the Sun.
Solar wind rains down on Earth's atmosphere constantly, but the intensity of this rain depends on solar activity. More than just a space phenomenon, solar wind can disrupt our telecommunication and navigation systems.
Solar Orbiter is on a mission to uncover the origin of the solar wind. It uses six imaging instruments to watch the Sun from closer than any spacecraft before, complemented by in situ instruments to measure the solar wind that flows past the spacecraft.
This video was recorded by the spacecraft's Metis instrument between 12:18 and 20:17 CEST on 12 October 2022. Metis is a coronagraph: it blocks the direct light coming from the Sun's surface to be able to see the much fainter light scattering from charged gas in its outer atmosphere, the corona.
Metis is currently the only instrument able to see the solar wind's twisting dance. No other imaging instrument can see – with a high enough resolution in both space and time – the Sun's inner corona where this dance takes place. (Soon, however, the coronagraph of ESA's Proba-3 mission might be able to see it too!)
The research paper that features this data, ‘Metis observations of Alfvénic outflows driven by interchange reconnection in a pseudostreamer’ by Paolo Romano et al. was published today in The Astrophysical Journal.
Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA.
[Technical details: The starting image of the video shows the full view of Solar Orbiter's Metis coronagraph in red, with an image from the spacecraft's Extreme Ultraviolet Imager in the centre (yellow). Zooming to the top left of this view, we see a video derived from Metis observations. The vertical edge of the video spans 1 274 000 km, or 1.83 solar radii. The contrast in the Metis video has been enhanced by using a ‘running difference’ technique: the brightness of each pixel is given by the average pixel brightness of three subsequent frames, minus the average pixel brightness of the three preceding frames. This processing makes background stars appear as horizontal half-dark, half-light lines. Diagonal bright streaks and flashes are caused by light scattering from dust particles close to the coronagraph.]
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