NASA's Webb Captures Celestial Fireworks Around Forming Star

L1527 and Protostar (MIRI Image)
Credits: Image: NASA, ESA, CSA, STScI

L1527 and Protostar (MIRI Compass Image)
Credits: Image: NASA, ESA, CSA, STScI

Images

---

The cosmos seems to come alive with a crackling explosion of pyrotechnics in this new image from NASA’s James Webb Space Telescope. Taken with Webb’s MIRI (Mid-Infrared Instrument), this fiery hourglass marks the scene of a very young object in the process of becoming a star. A central protostar grows in the neck of the hourglass, accumulating material from a thin protoplanetary disk, seen edge-on as a dark line. )

The protostar, a relatively young object of about 100,000 years, is still surrounded by its parent molecular cloud, or large region of gas and dust. Webb’s previous observation of L1527, with NIRCam (Near-Infrared Camera), allowed us to peer into this region and revealed this molecular cloud and protostar in opaque, vibrant colors.

Both NIRCam and MIRI show the effects of outflows, which are emitted in opposite directions along the protostar’s rotation axis as the object consumes gas and dust from the surrounding cloud. These outflows take the form of bow shocks to the surrounding molecular cloud, which appear as filamentary structures throughout. They are also responsible for carving the bright hourglass structure within the molecular cloud as they energize, or excite, the surrounding matter and cause the regions above and below it to glow. This creates an effect reminiscent of fireworks brightening a cloudy night sky. Unlike NIRCam, however, which mostly shows the light that is reflected off dust, MIRI provides a look into how these outflows affect the region’s thickest dust and gases.

The areas colored here in blue, which encompass most of the hourglass, show mostly carbonaceous molecules known as polycyclic aromatic hydrocarbons. The protostar itself and the dense blanket of dust and a mixture of gases that surround it are represented in red. (The sparkler-like red extensions are an artifact of the telescope’s optics). In between, MIRI reveals a white region directly above and below the protostar, which doesn’t show as strongly in the NIRCam view. This region is a mixture of hydrocarbons, ionized neon, and thick dust, which shows that the protostar propels this matter quite far away from it as it messily consumes material from its disk.

As the protostar continues to age and release energetic jets, it’ll consume, destroy, and push away much of this molecular cloud, and many of the structures we see here will begin to fade. Eventually, once it finishes gathering mass, this impressive display will end, and the star itself will become more apparent, even to our visible-light telescopes.

The combination of analyses from both the near-infrared and mid-infrared views reveal the overall behavior of this system, including how the central protostar is affecting the surrounding region. Other stars in Taurus, the star-forming region where L1527 resides, are forming just like this, which could lead to other molecular clouds being disrupted and either preventing new stars from forming or catalyzing their development.

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).

Source: NASA's James Webb Space Telescope/News

---

About This Release

Credits:

Media Contact:

Matthew Brown
Space Telescope Science Institute, Baltimore, Maryland

Christine Pulliam
Space Telescope Science Institute, Baltimore, Maryland

Permissions: Content Use Policy

Contact Us: Direct inquiries to the News Team.

---

Explaining the density profiles of dark matter halos with neural networks

Figure 1 | A neural network is trained to discover the underlying degrees of freedom in halo density profiles within a low-dimensional latent representation, when presented with the full 3D density structure of a halo at the present-day time (z=0). We physically interpret the discovered representation in terms of the halo’s evolution history by measuring the mutual information (MI) between the latent parameters and the assembly history of the halos.

Figure 2 | The MI between the latent parameters and the halo mass as a function of time (top row), and that between the latent parameters and the rate of change in mass as a function of time (bottom row). The inner shape latent and the NFW concentration carry memory of the early-time mass assembly history, as well as the later-time mass accretion rate. The outer shape latent carries information about the halos' most recent mass accretion rate over the past dynamical time (indicated by the arrow).

---

Can machine learning make new discoveries in astrophysics? An ‘explainable’ neural network is employed to get insights into the origin of dark matter halo density profiles. The network discovers that the shape of the profile in the halo outskirts is described by a single parameter related to the most recent accretion of mass. This is done without prior knowledge of the halo’s evolution history being provided during training.

Artificial intelligence (AI) has rapidly emerged as a powerful tool in astrophysics and cosmology. Typical uses of machine learning in cosmology include emulating the output of computationally expensive cosmological simulations, or accelerating the estimation of cosmological parameters from data. These approaches effectively treat machine learning models as “black boxes”: humans cannot understand the inner workings of these complex deep learning algorithms involving often millions of parameters. However, only by understanding how machine learning models reach their predictions can scientists trust AI tools in scientific applications.

MPA research fellow Luisa Lucie-Smith's research has focused on developing explainable machine learning frameworks for cosmological structure formation. In these frameworks, the machine learning results can be interpreted and explained in terms of the physics they represent. Luisa Lucie-Smith and her international colleagues designed a neural network, denoted an interpretable variational encoder (IVE), that generates a low-dimensional, compressed ‘latent’ representation of the input data. This latent representation captures all the relevant information about the final output of interest, and can be physically interpreted using the information-theoretic metric of mutual information (MI).

The team first applied the IVE method to discover the building blocks of the density profiles of dark matter halos. Halo density profiles are not only key ingredients of the galaxy-halo connection in cosmological analyses and of direct and indirect dark matter searches; they are also powerful observational testbeds of fundamental physics. This is because their shape, from the inner core to the outskirts, is sensitive to the nature of dark matter and modifications to gravity. However, on the theoretical side, models of halo density profiles still rely solely on empirically found fitting functions. Observationally, it has recently become possible to measure weak lensing and 3D density profiles through a combination of multi-wavelength data; our ability to make use of these measurements requires a more complete understanding of the physical effects that control the shape of the density profiles and their origin.

Given the 3D density structure of a dark matter halo at the present-day time (z=0), the IVE discovered that a three-dimensional latent space is required and sufficient to describe the density profiles of halos out to their outskirts, beyond the radial range of validity of traditional fitting functions such as Navarro-Frenk-White (NFW) profile (Fig. 1). The three-dimensional latent space is disentangled, meaning that each latent parameter captures an independent factor of variation in the halo density profile. Two latent parameters consist of a normalization and an inner shape parameter similar to the two parameters of the NFW profile; the third, additional latent describes the shape of the profile in the halo outskirts.    The team then exploits the latent space beyond its original training task, to connect the evolutionary history of dark matter halos with their density profiles. Without any prior knowledge of the halos' evolution being provided during training, the network recovers the known relation between early formation time and the shape of the inner profile. It additionally discovers that the outer profile, which can be described by a single degree of freedom, is sensitive to the halo's most recent mass accretion rate (Fig. 2).

The results of this study represent progress towards enabling new machine-assisted scientific discoveries, going beyond artificial rediscovery of known physical laws as presented so far in the literature. The IVE approach towards this goal consists of compressing the information within a dataset into a set of minimal ingredients which disentangles the independent factors of variation in the output (interpretability), and can be explained in terms of the physics it represents through MI (explainability).

Source: Max Planck Institute for Astrophysics/News

---

Author:

Luisa Lucie-Smith
Postdoc
2215
luisals@mpa-garching.mpg.de

---

Original publication

1. Lucie-Smith L.; Peiris H.V.; Pontzen A.

Explaining dark matter halo density profiles with neural networks
Physical Review Letters 132,    031001, January 2024.

DOI

2. Lucie-Smith L.; Peiris H.V.; Pontzen A.; Nord B.; Thiyagalingam J.; Piras, D.

Discovering the building blocks of dark matter halo density profiles with neural networks
Physical Review D, Volume 105, Issue 10, May 2022.

DOI

---

A maelstrom of matter and energy

NGC 4951

A spiral galaxy, tilted diagonally. It has thick, cloudy spiral arms wrapping around the core. They are filled with pink patches marking new star formation, young blue stars, and dark wisps of dust that block light. The galaxy glows brightly from its core. It is on a dark background, with a few distant galaxies and unrelated stars around it. Credit: ESA/Hubble & NASA, D. Thilker, M. Zamani (ESA/Hubble)

This Picture of the Week from the NASA/ESA Hubble Space Telescope depicts the galaxy NGC 4951, a spiral galaxy that’s located 49 million light-years from Earth in the constellation Virgo.

The data used to make this image were captured by Hubble as part of a programme to examine how matter and energy travel in nearby galaxies. Galaxies continuously undergo a cycle of star formation whereby the gas in a galaxy forms molecular clouds, which collapse to create new stars, which then disperse the clouds they formed from with powerful radiation or stellar winds in a process called feedback. The remaining gas is left to form new clouds elsewhere. This cycle of moving matter and energy determines how fast a galaxy forms stars and how quickly it burns through its supplies of gas — that is, how it evolves over the course of its life. Understanding this evolution depends on the nebulae, stars and star clusters in the galaxy: when they formed and their past behaviour. Hubble has always excelled at measuring populations of stars, and the task of tracking gas and star formation in galaxies including NGC 4951 is no exception.

NGC 4951 is also a Seyfert galaxy, a type of galaxy that has a very bright and energetic nucleus called an active galactic nucleus. This image demonstrates well how energetic the galaxy is, and some of the dynamic galactic activity which transports matter and energy throughout it: a shining core surrounded by swirling arms, glowing pink star-forming regions, and thick dust.

Links

• Pan of NGC 4951

Source: ESA/Hubble/potw

---

Dimorphos, from Up Close and Far Away

The spatially resolved reflectance of the asteroid Dimorphos as measured by the DART spacecraft.
Adapted from Buratti et al. 2024

The Double Asteroid Redirection Test (DART) mission marked humanity’s first attempt to alter the course of an asteroid, a technique that could one day avert a catastrophic impact and save countless lives. But to fully understand the outcome of the experiment and to determine the impact of the human-caused impact, astronomers need a detailed characterization of their target. A recent study aims to bridge observations taken by DART moments before its demise and those taken from back on Earth in order to measure surface properties that neither dataset could constrain alone.

The surface of Dimorphos, as seen by the DART spacecraft 2 seconds before impact.
Credit: NASA/Johns Hopkins APL

Intentional Collision and In-Situ Measurements

In September 2022, NASA’s DART spacecraft approached a near-Earth asteroid named Didymos and its moon, Dimorphos. With cameras trained on Dimorphos specifically, DART took pictures with ever-increasing resolution as the distance to the moon’s surface steadily shrank. Unfortunately for both DART and Dimorphos, though, this was not a flyby mission. Instead of changing course, DART plowed straight into the moon with enough momentum to dig a fresh crater and to change the satellite’s orbital period by more than 30 minutes.

The main purpose of this intentional collision was to test if it’d be possible to redirect an asteroid’s path through a brute-force impact. This is a potentially humanity-saving skill, should astronomers ever discover a large asteroid destined to collide with Earth absent a dramatic intervention, and scientists involved with the mission want to be confident that everything they learn from this single collision is applicable to any future high-stakes redirections. To more confidently extrapolate the results of this test to larger asteroids with structures and compositions that might differ from Dimophos’s, astronomers need to measure every material property of this one asteroid that they can.

Some of these properties are best measured from up close to the asteroid, and the images beamed back by DART moments before its abrupt end contain much useful information. Others, though, such as how the surface scatters light, are better constrained by observing the asteroid from many different angles, which one can do by taking observations from Earth over many months. By combining these different types of measurements, a fuller picture emerges than could be built by either dataset alone.

The solar phase curve of Dimorphos as measured from Table Mountain Observatory.
Credit: Buratti et al. 2024

Adding in Ground-Based Observations

This combination is what Bonnie Buratti, Jet Propulsion Laboratory, and collaborators accomplished in a recent study. The researchers took observations from Table Mountain Observatory of the Didymos/Dimorphos system over about five months in order to build a solar phase curve, or how the brightness of the two asteroids changes with respect to our viewing angle. This allowed them to build a particle phase function, or a model of how the surface scatters light. Then, by poring over and reprocessing the DART images, Buratti and colleagues were able to quantify the surface roughness of the asteroid, a property that would have been impossible to disentangle from the phase function without the extra information gathered from the ground.

This synthesis demonstrates that although the missions we send up to gather exquisite in-situ data, sometimes important, fundamental properties require patient observations from back home as well. In 2026, the European Space Agency’s Hera spacecraft will arrive at Didymos to survey the damage, and analysis of its data will rely heavily on context learned through studies like these in the intervening years.

By Ben Cassese

Citation

“Pre-impact Albedo Map and Photometric Properties of the (65803) Didymos Asteroid Binary System from DART and Ground-Based Data,” B. J. Buratti et al 2024 Planet. Sci. J. 5 83. doi:10.3847/PSJ/ad2b60

Source: American Astronomical Society/AAS-Nova

---

Gemini North Captures Starburst Galaxy Blazing Bright With Newly Forming Stars

PR Image noirlab2416a
Starburst Galaxy NGC 4449

PR Image noirlab2416b
The Milky Way Over Gemini North

PR Image noirlab2416c
Gemini North Dedication Ceremony

---

Videos

PR Video noirlab2416a
Cosmoview Episode 83: Gemini North Captures Starburst Galaxy Blazing Bright With Newly Forming Stars

PR Video noirlab2416b
Pan on NGC 4449

PR Video noirlab2416d

Cosmoview Episodio 83: Telescopio de Gemini Norte celebra nuevo aniversario con el confeti cósmico de una devoradora galáctica

---

Irregular galaxy NGC 4449 exhibits explosive rate of star formation activity due in part to ongoing mergers with nearby dwarf galaxies

A festive array of bright pinks and blues makes for a remarkable sight in this image captured with the Gemini North telescope, one half of the International Gemini Observatory. Resembling a cloud of cosmic confetti, this image is being released in celebration of Gemini North’s 25th anniversary. NGC 4449 is a prime example of starburst activity caused by the interacting and mingling of galaxies as it slowly absorbs its smaller galactic neighbors.

Much of the visible matter in the Universe, the matter that makes up stars, planets — and us — is made inside stars as they complete their cycle of birth, life, and death. They are born from clouds of gas and dust, and when they die their remains are recycled back into the interstellar medium to be used as fuel for the next generation of stars. And in a not-so-distant corner of the Universe, 13 million light-years away in the constellation Canes Venatici, the beginning of this cycle is unfolding at an exceptional rate.

NGC 4449, also known as Caldwell 21, appears to be putting on a cosmic fireworks show in this image, captured with the Gemini North telescope, one half of the International Gemini Observatory, which is supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab. The galaxy’s billowing red clouds and sparkling blue veil are lighting up the sky with the colors of newly forming stars. It’s classified as an irregular Magellanic-type galaxy, reflecting its loose spiral structure and close resemblance to the Large Magellanic Cloud — the prototype of Magellanic galaxies.

Stars have been actively forming within NGC 4449 for several billion years, but currently it is pumping out new stars at a much higher rate than in the past. This unusually explosive and intense star formation activity qualifies it as a starburst galaxy. While starbursts usually occur in the central regions of galaxies, NGC 4449’s star formation is more widespread, evidenced by the fact that the youngest stars are both in the nucleus and in streams surrounding the galaxy.

This ‘global’ starburst activity resembles the Universe’s earliest star-forming galaxies, which grew by merging with and accreting smaller stellar systems. And like its galactic predecessors, NGC 4449’s rapid star formation was likely ignited by interactions with neighboring galaxies. As a member of the M94 Group of galaxies — one of the closest galaxy groups to the Local Group, which hosts the Milky Way — NGC 4449 lies in close proximity to a handful of surrounding smaller galaxies. Astronomers have found evidence of interactions between NGC 4449 and at least two of these satellite galaxies.

One is a very dim dwarf galaxy that is actively being absorbed, as evidenced by a diffuse stream of stars extending to one side of NGC 4449. This ‘stealth’ merger is nearly undetectable by visual inspection owing to its diffuse nature and low stellar mass. However, it possesses a large amount of dark matter, meaning its presence can be detected by the substantial gravitational influence it has on NGC 4449. The other object that provides hints of a past merger is a massive globular star cluster embedded within the outer halo of NGC 4449. This cluster is thought by astronomers to be the surviving nucleus of a former gas-rich satellite galaxy now in the process of being absorbed by NGC 4449.

As NGC 4449 interacts with and absorbs its smaller galactic companions, the tidal interactions between the galaxies compress and shock the gas. The glowing red regions scattered across this image showcase this process, indicating an abundance of ionized hydrogen — a telltale sign of ongoing star formation. A plethora of hot, young blue star clusters are emerging from the galactic ovens, fueled by the dark filaments of cosmic dust lacing throughout the galaxy. At the current rate, the gas supply that feeds NGC 4449’s production of stars will only last for another billion years or so.

This image is being released today in celebration of the Gemini North telescope’s 25th anniversary. On 25 June 1999 a dedication ceremony was held on Maunakea, Hawai‘i, to unveil the new world-class 8.1-meter telescope and reveal its first-light images, which at the time were some of the sharpest infrared images ever obtained by a ground-based telescope. Over the past two and a half decades Gemini North’s large mirror, powerful suite of instruments and advanced adaptive optics have allowed astronomers to peer further and further into the cosmos. From capturing the first direct image of a multi-planet system to testing Einstein’s general theory of relativity — which helped astronomers earn the 2020 Nobel Prize — Gemini North has contributed greatly to humanity’s understanding of the Universe.

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

---

More information

NSF NOIRLab (U.S. National Science Foundation National Optical-Infrared Astronomy Research Laboratory), the U.S. center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

---

Links

• Explore NGC 4449 in more detail
• Photos of Gemini North
• Videos of Gemini North
• Check out other NOIRLab Photo Releases

---

Contacts:

Josie Fenske
NSF NOIRLab
Email: josie.fenske@noirlab.edu

---