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NuSTAR’s First Five Years in Space

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Artist’s Concept of NuSTAR

Artist’s concept of NuSTAR on orbit. NuSTAR has a 10-m (30′) mast that deploys after launch to separate the optics modules (right) from the detectors in the focal plane (left). The spacecraft, which controls NuSTAR’s pointings, and the solar panels are with the focal plane. NuSTAR has two identical optics modules in order to increase sensitivity. The background is an image of the Galactic center obtained with the Chandra X-ray Observatory.

NuSTAR’s mission operations center is at UC Berkeley. The outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.
Credit: NASA/JPL-Caltech

 

NuSTAR’s First Five Years in Space

Five years ago, on June 13, 2012, Caltech’s Fiona Harrison, principal investigator of NASA’s NuSTAR mission, watched with her team as their black-hole-spying spacecraft was launched into space aboard a rocket strapped to the belly of an aircraft. The launch occurred over the Kwajalein Atoll in the Marshall Islands. Many members of the team anxiously followed the launch from the mission’s operations center at the University of California, Berkeley, anxious to see what NuSTAR would find.

Now, Harrison shares her take on five of the mission’s many iconic images and artist concepts — ranging from our flaring sun to distant, buried black holes. NuSTAR is the first telescope capable of focusing high-energy X-rays — and it has taken the most detailed images of the sky in this energy regime to date.

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Black Holes: Monsters in Space (Artist’s Concept)

This artist’s concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. (Smaller black holes also exist throughout galaxies.) In this illustration, the supermassive black hole at the center is surrounded by matter flowing onto the black hole in what is termed an accretion disk. This disk forms as the dust and gas in the galaxy falls onto the hole, attracted by its gravity.

Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole’s spin. The regions near black holes contain compact sources of high energy X-ray radiation thought, in some scenarios, to originate from the base of these jets. This high energy X-radiation lights up the disk, which reflects it, making the disk a source of X-rays. The reflected light enables astronomers to see how fast matter is swirling in the inner region of the disk, and ultimately to measure the black hole’s spin rate.
Image credit: NASA/JPL-Caltech

 

“This is an artist’s concept of a region very near a black hole,” Harrison said. “It was made to go along with some of our very first results, where we measured the spin of a supermassive black hole unambiguously for the first time. NuSTAR’s high-energy X-ray vision allowed us to distinguish between models that explain what produces black holes’ X-ray emissions, and this information led us to conclude that the observed black hole is rapidly spinning.

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Untangling the Remains of Cassiopeia A

The mystery of how Cassiopeia A exploded is unraveling thanks to new data from NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR. In this image, NuSTAR data, which show high-energy X-rays from radioactive material, are colored blue. Lower-energy X-rays from non-radioactive material, imaged previously with NASA’s Chandra X-ray Observatory, are shown in red, yellow and green.

The new view shows a more complete picture of Cassiopeia A, the remains of a star that blew up in a supernova event whose light reached Earth about 350 years ago, when it could have appeared to observers as a star that suddenly brightened. The remnant is located 11,000 light-years away from Earth.

NuSTAR is the first telescope capable of taking detailed pictures of the radioactive material in the Cassiopeia A supernova remnant. While other telescopes have detected radioactivity in these objects before, NuSTAR is the first capable of pinpointing the location of the radioactivity, creating maps. When massive star explode, they create many elements: non-radioactive ones like iron and calcium found in your blood and bones; and radioactive elements like titanium-44, the decay of which sends out high-energy X-ray light that NuSTAR can see.

By mapping titanium-44 in Cassiopeia A, astronomers get a direct look at what happened in the core of the star when it was blasted to smithereens. These NuSTAR data complement previous observations made by Chandra, which show elements, such as iron, that were heated by shock waves farther out from the remnant’s center.

In this image, the red, yellow and green data were collected by Chandra at energies ranging from 1 to 7 kiloelectron volts (keV). The red color shows heated iron, and green represents heated silicon and magnesium. The yellow is what astronomers call continuum emission, and represents a range of X-ray energies.

The titanium-44, shown in blue, was detected by NuSTAR at energies ranging between 68 and 78 keV.

The NuSTAR observations point to a possible solution to the puzzle of how stars detonate. The fact that the titanium — which is a direct tracer of the supernova blast — is concentrated in clumps at the core supports a theory referred to as “mild asymmetries.” In this scenario, material sloshes about at the heart of the supernova, reinvigorating a shock wave and allowing it to blow out the star’s outer layers.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, N.Y.; NASA’s Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; ATK Aerospace Systems, Goleta, Calif., and with support from the Italian Space Agency (ASI) Science Data Center, Rome, Italy.

NuSTAR’s mission operations center is at UC Berkeley, with ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.
Image credit: NASA/JPL-Caltech/CXC/SAO

 

“This is a beautiful image, and one of the things we built NuSTAR to do — to make the first-ever map of emission from radioactivity in the remnant of an exploded star,” Harrison said. “We spent years developing specialized detectors to have the capability to make this image. From the image, we were able to determine the mechanism that caused the star to explode.” NuSTAR data show high-energy X-rays from radioactive material in blue. Non-radioactive materials are red, yellow and green.

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NuSTAR Finds a Pulse in Cigar Galaxy

High-energy X-rays streaming from a rare and mighty pulsar (magenta), the brightest found to date, can be seen in this new image combining multi-wavelength data from three telescopes. The bulk of a galaxy called Messier 82 (M82), or the “Cigar galaxy,” is seen in visible-light data captured by the National Optical Astronomy Observatory’s 2.1-meter telescope at Kitt Peak in Arizona. Starlight is white, and lanes of dust appear brown. Low-energy X-ray data from NASA’s Chandra X-ray Observatory are colored blue, and higher-energy X-ray data from NuSTAR are pink.

The magenta object is what’s known as an ultraluminous X-ray source, or ULX — a source of blazing X-rays. Previously, all ULXs were suspected to be massive black holes up to a few hundred times the mass of the sun. But NuSTAR spotted a pulsing of X-rays from this ULX (called M82 X-2) – a telltale sign of a pulsar, not a black hole. A pulsar is a type a neutron star — a stellar core left over from a supernova explosion — that sends out rotating beams of high-energy radiation. Scientists were surprised to find the pulsar at the root of the ULX because it shines with a luminosity that is more typical of heftier black holes.

NuSTAR data covers the X-ray energy range of 10 to 40 kiloelectron volts (keV), and Chandra covers the range .1 to 10 keV.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Virginia. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA’s Goddard Space Flight Center, Greenbelt, Maryland; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, California; ATK Aerospace Systems, Goleta, California, and with support from the Italian Space Agency (ASI) Science Data Center.

NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, California. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.
Image credit: NASA/JPL-Caltech/SAO/NOAO

 

“This result was one of the biggest surprises from NuSTAR. We detected X-ray pulses from an object in a galaxy that everybody had assumed was a black hole, thereby showing it was actually a stellar remnant called a pulsar. At the time, it was by far the brightest pulsar known. At first nobody believed it, but the signal was so strong and clear,” Harrison said. Since this discovery two other extremely bright pulsars have been found — prompted by NuSTAR’s discovery. High-energy X-rays from the pulsar are seen in pink at the center of the image.

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NuSTAR Stares at the Sun

Flaring, active regions of our sun are highlighted in this image combining observations from several telescopes. High-energy X-rays from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) are shown in blue; low-energy X-rays from Japan’s Hinode spacecraft are green; and extreme ultraviolet light from NASA’s Solar Dynamics Observatory (SDO) is yellow and red.

All three telescopes captured their solar images around the same time on April 29, 2015. The NuSTAR image is a mosaic made from combining smaller images.

The active regions across the sun’s surface contain material heated to several millions of degrees. The blue-white areas showing the NuSTAR data pinpoint the most energetic spots. During the observations, microflares went off, which are smaller versions of the larger flares that also erupt from the sun’s surface. The microflares rapidly release energy and heat the material in the active regions.

NuSTAR typically stares deeper into the cosmos to observe X-rays from supernovas, black holes and other extreme objects. But it can also look safely at the sun and capture images of its high-energy X-rays with more sensitivity than before. Scientists plan to continue to study the sun with NuSTAR to learn more about microflares, as well as hypothesized nanoflares, which are even smaller.

In this image, the NuSTAR data shows X-rays with energies between 2 and 6 kiloelectron volts; the Hinode data, which is from the X-ray Telescope instrument, has energies of 0.2 to 2.4 kiloelectron volts; and the Solar Dynamics Observatory data, taken using the Atmospheric Imaging Assembly instrument, shows extreme ultraviolet light with wavelengths of 171 and 193 Angstroms.

Note the green Hinode image frame edge does not extend as far as the SDO ultraviolet image, resulting in the green portion of the image being truncated on the right and left sides.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Virginia. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA’s Goddard Space Flight Center, Greenbelt, Maryland; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, California; ATK Aerospace Systems, Goleta, California, and with support from the Italian Space Agency (ASI) Science Data Center.

NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, California. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.
Image credit: NASA/JPL-Caltech/GSFC/JAXA

 

“With NuSTAR, we see flaring, active regions of the sun where high-energy particles are being created. NuSTAR was built as an astrophysics mission, not to study the sun,” Harrison said. “People thought we were crazy at first to point such a sensitive observatory at the sun and potentially ruin it. But now, by studying the sun with much greater sensitivity in high-energy X-rays, we are making important contributions to the field of solar physics.”

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Galaxy NGC 1448 with Active Galactic Nucleus

NGC 1448, a galaxy with an active galactic nucleus, is seen in this image combining data from the Carnegie-Irvine Galaxy Survey in the optical range and NuSTAR in the X-ray range.

This galaxy contains an example of a supermassive black hole hidden by gas and dust. X-ray emissions from NGC 1448, as seen by NuSTAR and Chandra, suggests for the first time that, like IC 3639 in PIA21087, there must be a thick layer of gas and dust hiding the active black hole in this galaxy from our line of sight.

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.
Image credit: NASA/JPL-Caltech/Carnegie-Irvine Galaxy Survey

 

“This image illustrates another major accomplishment NuSTAR was designed for — to find hidden black holes buried by dust and gas,” Harrison said. “This is a wonderful result, led by two graduate students. What they found is that there is a thick layer of gas and dust hiding the active black hole in the galaxy NGC 1448 from our sight.”

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

source: NASA – Jet Propulsion Laboratory – California Institute of Technology

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