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By NASA
2 min read
Hubble Traces Star Formation in a Nearby Nebula
NASA, ESA, and L. C. Johnson (Northwestern University); Image Processing: Gladys Kober (NASA/Catholic University of America) NGC 261 blooms a brilliant ruby red against a myriad of stars in this new image from NASA’s Hubble Space Telescope. Discovered on Sept. 5, 1826 by Scottish astronomer James Dunlop, this nebula is located in one of the Milky Way’s closest galactic companions, the Small Magellanic Cloud (SMC). The ionized gas blazing from within this diffuse region marks NGC 261 as an emission nebula. It is home to numerous stars hot enough to irradiate surrounding hydrogen gas, causing the cloud to emit a pinkish-red glow.
This inset image shows the location of NGC 261 within the Small Magellanic Cloud. NASA, ESA, L. C. Johnson (Northwestern University), and ESO/VISTA VMC; Image Processing: Gladys Kober (NASA/Catholic University of America) Hubble turned its keen eye toward NGC 261 to investigate how efficiently stars form in molecular clouds, which are extremely dense and compact regions of gas and dust. These clouds often consist of large amounts of molecular hydrogen — cold areas where most stars form. However, measuring this raw fuel of star formation in stellar nurseries is a challenge because molecular hydrogen doesn’t radiate easily. Since it is difficult to detect, scientists instead trace other molecules present in the molecular clouds.
The SMC hosts a gas-rich environment of young stars along with trace amounts of carbon monoxide (CO), a chemical correlated with hydrogen and often used to identify the presence of such clouds. Using the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3), Hubble imaged these stars in the southwest portion of the SMC where NGC 261 resides. The combined power of ACS and WFC3 allowed scientists to closely examine the nebula’s star-forming properties through its CO content at optical and near-infrared wavelengths. This research helps astronomers better understand how stars form in our home galaxy and others in our galactic neighborhood.
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Last Updated Aug 28, 2024 Editor Michelle Belleville Location NASA Goddard Space Flight Center Related Terms
Astrophysics Galaxies Goddard Space Flight Center Hubble Space Telescope Stars Keep Exploring Discover More Topics From NASA
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Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
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By NASA
ESA/Hubble & NASA, J. Tan (Chal This NASA/ESA Hubble Space Telescope image presents a visually striking collection of interstellar gas and dust. Named RCW 7, the nebula is located just over 5,300 light-years from Earth in the constellation Puppis.
Nebulae are areas rich in the raw material needed to form new stars. Under the influence of gravity, parts of these molecular clouds collapse until they coalesce into very young, developing stars, called protostars, which are still surrounded by spinning discs of leftover gas and dust. The protostars forming in RCW 7 are particularly massive, giving off strongly ionizing radiation and fierce stellar winds that transformed the nebula into a H II region.
H II regions are filled with hydrogen ions — H I refers to a normal hydrogen atom, while H II is hydrogen that lost its electron making it an ion. Ultraviolet radiation from the massive protostars excites the hydrogen in the nebula, causing it to emit light that gives this nebula its soft pinkish glow.
The Hubble data in this image came from the study of a particularly massive protostellar binary named IRAS 07299-1651, still in its glowing cocoon of gas in the curling clouds toward the top of the image. To expose this star and its siblings, astronomers used Hubble’s Wide Field Camera 3 in near-infrared light. The massive protostars in this image are brightest in ultraviolet light, but they emit plenty of infrared light too. Infrared light’s longer wavelength lets it pass through much of the gas and dust in the cloud allowing Hubble to capture it. Many of the larger-looking stars in this image are foreground stars that are not part of the nebula. Instead, they sit between the nebula and our solar system.
The creation of an H II region marks the beginning of the end for a molecular cloud like RCW 7. Within only a few million years, radiation and winds from the massive stars will gradually disperse the nebula’s gas — even more so as the most massive stars come to the end of their lives in supernova explosions. New stars in this nebula will incorporate only a fraction of the nebula’s gas, the rest will spread throughout the galaxy to eventually form new molecular clouds.
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By NASA
2 min read
Hubble Captures Infant Stars Transforming a Nebula
This striking NASA/ESA Hubble Space Telescope image features the nebula RCW 7. ESA/Hubble & NASA, J. Tan (Chalmers University & University of Virginia), R. Fedriani This NASA/ESA Hubble Space Telescope image presents a visually striking collection of interstellar gas and dust. Named RCW 7, the nebula is located just over 5,300 light-years from Earth in the constellation Puppis.
Nebulae are areas rich in the raw material needed to form new stars. Under the influence of gravity, parts of these molecular clouds collapse until they coalesce into very young, developing stars, called protostars, which are still surrounded by spinning discs of leftover gas and dust. The protostars forming in RCW 7 are particularly massive, giving off strongly ionizing radiation and fierce stellar winds that transformed the nebula into a H II region.
H II regions are filled with hydrogen ions — H I refers to a normal hydrogen atom, while H II is hydrogen that lost its electron making it an ion. Ultraviolet radiation from the massive protostars excites the hydrogen in the nebula, causing it to emit light that gives this nebula its soft pinkish glow.
The Hubble data in this image came from the study of a particularly massive protostellar binary named IRAS 07299-1651, still in its glowing cocoon of gas in the curling clouds toward the top of the image. To expose this star and its siblings, astronomers used Hubble’s Wide Field Camera 3 in near-infrared light. The massive protostars in this image are brightest in ultraviolet light, but they emit plenty of infrared light too. Infrared light’s longer wavelength lets it pass through much of the gas and dust in the cloud allowing Hubble to capture it. Many of the larger-looking stars in this image are foreground stars that are not part of the nebula. Instead, they sit between the nebula and our solar system.
The creation of an H II region marks the beginning of the end for a molecular cloud like RCW 7. Within only a few million years, radiation and winds from the massive stars will gradually disperse the nebula’s gas — even more so as the most massive stars come to the end of their lives in supernova explosions. New stars in this nebula will incorporate only a fraction of the nebula’s gas, the rest will spread throughout the galaxy to eventually form new molecular clouds.
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Last Updated Jun 21, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Astrophysics Astrophysics Division Goddard Space Flight Center Hubble Space Telescope Missions Nebulae Protostars Stars The Universe Keep Exploring Discover More Topics From Hubble
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Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
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By NASA
6 Min Read Investigating the Origins of the Crab Nebula With NASA’s Webb
This image by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) shows different structural details of the Crab Nebula. New data revises our view of this unusual supernova explosion.
A team of scientists used NASA’s James Webb Space Telescope to parse the composition of the Crab Nebula, a supernova remnant located 6,500 light-years away in the constellation Taurus. With the telescope’s MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera), the team gathered data that is helping to clarify the Crab Nebula’s history.
The Crab Nebula is the result of a core-collapse supernova from the death of a massive star. The supernova explosion itself was seen on Earth in 1054 CE and was bright enough to view during the daytime. The much fainter remnant observed today is an expanding shell of gas and dust, and outflowing wind powered by a pulsar, a rapidly spinning and highly magnetized neutron star.
The Crab Nebula is also highly unusual. Its atypical composition and very low explosion energy previously have been explained by an electron-capture supernova — a rare type of explosion that arises from a star with a less-evolved core made of oxygen, neon, and magnesium, rather than a more typical iron core.
“Now the Webb data widen the possible interpretations,” said Tea Temim, lead author of the study at Princeton University in New Jersey. “The composition of the gas no longer requires an electron-capture explosion, but could also be explained by a weak iron core-collapse supernova.”
Image A: Crab Nebula (NIRCam and MIRI)
This image by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) shows different structural details of the Crab Nebula. The supernova remnant is comprised of several different components, including doubly ionized sulfur (represented in green), warm dust (magenta), and synchrotron emission (blue). Yellow-white mottled filaments within the Crab’s interior represent areas where dust and doubly ionized sulfur coincide. The observations were taken as part of General Observer program 1714. Studying the Present to Understand the Past
Past research efforts have calculated the total kinetic energy of the explosion based on the quantity and velocities of the present-day ejecta. Astronomers deduced that the nature of the explosion was one of relatively low energy (less than one-tenth that of a normal supernova), and the progenitor star’s mass was in the range of eight to 10 solar masses — teetering on the thin line between stars that experience a violent supernova death and those that do not.
However, inconsistencies exist between the electron-capture supernova theory and observations of the Crab, particularly the observed rapid motion of the pulsar. In recent years, astronomers have also improved their understanding of iron core-collapse supernovae and now think that this type can also produce low-energy explosions, providing that the stellar mass is adequately low.
Webb Measurements Reconcile Historic Results
To lower the level of uncertainty surrounding the Crab’s progenitor star and nature of the explosion, the team led by Temim used Webb’s spectroscopic capabilities to hone in on two areas located within the Crab’s inner filaments.
Theories predict that because of the different chemical composition of the core in an electron-capture supernova, the nickel to iron (Ni/Fe) abundance ratio should be much higher than the ratio measured in our Sun (which contains these elements from previous generations of stars). Studies in the late 1980s and early 1990s measured the Ni/Fe ratio within the Crab using optical and near-infrared data and noted a high Ni/Fe abundance ratio that seemed to favor the electron-capture supernova scenario.
The Webb telescope, with its sensitive infrared capabilities, is now advancing Crab Nebula research. The team used MIRI’s spectroscopic abilities to measure the nickel and iron emission lines, resulting in a more reliable estimate of the Ni/Fe abundance ratio. They found that the ratio was still elevated compared to the Sun, but only modestly and much lower in comparison to prior estimates.
The revised values are consistent with electron-capture, but do not rule out an iron core-collapse explosion from a similarly low-mass star. (Higher-energy explosions from higher-mass stars are expected to produce ratios closer to solar abundances.) Further observational and theoretical work will be needed to distinguish between these two possibilities.
“At present, the spectral data from Webb covers two small regions of the Crab, so it’s important to study much more of the remnant and identify any spatial variations,” said Martin Laming of the Naval Research Laboratory in Washington and a co-author of the paper. “It would be interesting to see if we could identify emission lines from other elements, like cobalt or germanium.”
Video: Crab Nebula Deconstructed
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This video shows the different major components that compose the Crab Nebula as observed by the James Webb Space Telescope. Despite decades of study, this supernova remnant continues to puzzle astronomers as they seek to understand what kind of progenitor star and explosion produced this dynamic environment. Image- NASA, ESA, CSA, STScI, Tea Temim (Princeton University) Video- Joseph DePasquale (STScI) Mapping the Crab’s Current State
Besides pulling spectral data from two small regions of the Crab Nebula’s interior to measure the abundance ratio, the telescope also observed the remnant’s broader environment to understand details of the synchrotron emission and the dust distribution.
The images and data collected by MIRI enabled the team to isolate the dust emission within the Crab and map it in high resolution for the first time. By mapping the warm dust emission with Webb, and even combining it with the Herschel Space Observatory’s data on cooler dust grains, the team created a well-rounded picture of the dust distribution: The outermost filaments contain relatively warmer dust, while cooler grains are prevalent near the center.
“Where dust is seen in the Crab is interesting because it differs from other supernova remnants, like Cassiopeia A and Supernova 1987A,” said Nathan Smith of the Steward Observatory at the University of Arizona and a co-author of the paper. “In those objects, the dust is in the very center. In the Crab, the dust is found in the dense filaments of the outer shell. The Crab Nebula lives up to a tradition in astronomy: The nearest, brightest, and best-studied objects tend to be bizarre.”
These findings have been accepted for publication in The Astrophysical Journal Letters.
The observations were taken as part of General Observer program 1714.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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These findings have been accepted for publication in The Astrophysical Journal Letters.
Media Contacts
Laura Betz – laura.e.betz@nasa.gov, Rob Gutro – rob.gutro@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Abigail Major – amajor@stsci.edu / Christine Pulliam – cpulliam@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
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Sonification: Multiwavelength image of the Crab Nebula
Explore More: Crab Nebula resources from NASA’s Universe of Learning
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Last Updated Jun 17, 2024 Editor Stephen Sabia Contact Laura Betz laura.e.betz@nasa.gov Related Terms
Astrophysics Crab Nebula Goddard Space Flight Center James Webb Space Telescope (JWST) Nebulae Neutron Stars Pulsars Science & Research Stars Supernovae The Universe View the full article
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By European Space Agency
Image: This Copernicus Sentinel-3 image from October 2023 captures the plains of northern India and Pakistan under a white veil of haze and smoke. View the full article
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