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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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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 NASA
3 min read
December’s Night Sky Notes: A Flame in the Sky – the Orion Nebula
Orion constellation Stellarium Web by Kat Troche of the Astronomical Society of the Pacific
It’s that time of year again: Winter! Here in the Northern Hemisphere, the clear, crisp sky offers spectacular views of various objects, the most famous of all being Orion the Hunter.
As we’ve previously mentioned, Orion is a great way to test your sky darkness. With the naked eye, you can easily spot this hourglass-shaped constellation. Known as an epic hunter in Greco-Roman antiqity, Orion and all its parts have many names and meanings across many cultures. In Egyptian mythology, this constellation represented the god Sah. The Babylonians referred to it as The Heavenly Shepard. In most cultures, it is Orion’s Belt that has many stories: Shen in Chinese folklore, or Tayamnicankhu in Lakota storytelling. But the Maya of Mesoamerica believed that part of Orion contained The Cosmic Hearth – the fire of creation.
1,500 light years away from Earth sits the star-forming region, and crown jewel of Orion – Messier 42 (M42), the Orion Nebula. Part of the “sword” of Orion, this 24 light year wide cloud of dust and gas sits below the first star in Orion’s Belt, Alnitak, and can easily be spotted with the naked eye under moderate dark skies. You can also use binoculars or a telescope to resolve more details, such as the Trapezium: four stars in the shape of a keystone (or baseball diamond). These young stars make up the core of this magnificent object.
Of course, it’s not just for looking at! M42 is easily one of the most photographed nebulae around, imaged by amateur astrophotographers, professional observatories and space telescopes alike. It has long been a place of interest for the Hubble, Spitzer, and Chandra X-ray Space Telescopes, with James Webb Space Telescope now joining the list in February 2023. Earlier this year, NASA and the European Space Agency released a new photo of the Orion Nebula taken from JWST’s NIRCam (Near-Infrared Camera), which allowed scientists to image this early star forming region in both short and long wavelengths.
These Webb images show a part of the Orion Nebula known as the Orion Bar. It is a region where energetic ultraviolet light from the Trapezium Cluster — located off the upper-left corner — interacts with dense molecular clouds. The energy of the stellar radiation is slowly eroding the Orion Bar, and this has a profound effect on the molecules and chemistry in the protoplanetary disks that have formed around newborn stars here. The largest image, on the left, is from Webb’s NIRCam (Near-Infrared Camera) instrument. At upper right, the telescope is focused on a smaller area using Webb’s MIRI (Mid-Infrared Instrument). A total of eighteen filters across both the MIRI and NIRCam instruments were used in these images, covering a range of wavelengths from 1.4 microns in the near-infrared to 25.5 microns in the mid-infrared.
At the very center of the MIRI area is a young star system with a planet-forming disk named d203-506. The pullout at the bottom right displays a combined NIRCam and MIRI image of this young system. Its extended shape is due to pressure from the harsh ultraviolet radiation striking it. An international team of astronomers detected a new carbon molecule known as methyl cation for the first time in d203-506.
ESA/Webb, NASA, CSA, M. Zamani (ESA/Webb), PDRs4ALL ERS Team But stars aren’t the only items visible here. In June 2023, JWST’s NIRCam and MIRI (mid-infrared instrument) imaged a developing star system with a protoplanetary disk forming around it. That’s right – a solar system happening in real time – located within the edges of a section called the Orion Bar. Scientists have named this planet-forming disk d203-506, and you can learn more about the chemistry found here. By capturing these objects in multiple wavelengths of light, astronomers now have even greater insight into what other objects might be hiding within these hazy hydrogen regions of our night sky. This technique is called Multi-spectral Imaging, made possible by numerous new space based telescopes.
In addition to the Night Sky Network Dark Sky Wheel, a fun activity you can share with your astronomy club would be Universe Discovery Guide: Orion Nebula, Nursery of Newborn Stars. This will allow you to explain to audiences how infrared astronomy, like JWST, helps to reveal the secrets of nebulae. Or you can use public projects like the NASA-funded MicroObservatory to capture M42 and other objects.
Stay tuned to learn more about what to spy in the Winter sky with our upcoming mid-month article!
3 min read
December’s Night Sky Notes: A Flame in the Sky – the Orion Nebula
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