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Institute of Astronomy

 

Tue 06 May 11:00: Steven Benner: How life could not NOT originate on rocky planets, Earth, Mars, and 100 billion others in the Milky Way Galaxy

Next External Talks - Mon, 05/05/2025 - 12:40
Steven Benner: How life could not NOT originate on rocky planets, Earth, Mars, and 100 billion others in the Milky Way Galaxy

In Person

Prebiotic chemistry these days on Earth operates on two different metaphorical “worlds”. On one, leading with the elegant work of the Sutherland, Simons, and Leverhulme teams, the focus is on surface photochemistry of molecules arising from hazy reduced atmospheres, in particular, those where nitrogen is at the oxidation level of ammonia. It has not (yet) produced a single molecule of RNA , the (proposed) informational molecule that (purportedly) initiated Darwinian evolution.

In this talk, a visitor from the other world will show how oligomeric RNA with 3’,5’-linkages 150 ± 50 nucleotides long forms as the natural outcome of “privileged” chemistry beneath redox neutral atmospheres that are transiently reduced by Vesta-to-Ceres sized impactors. On Earth, this most likely happened 4.30 ± 0.05 billion years ago.

This RNA is long enough, and stereoregular enough, to have provided catalysts to support an “RNA World”. This World invented protein translation 4.20 ±0.11 billion years ago (based on arguable molecular clocks), and was sufficiently widespread to have left isotope enriched carbon entrapped in zircons dated at 4.10 billion years ago.

The production of pentoses (like ribose, ~100 kg/km2 per year ) cannot NOT happen on such worlds, if covered by basalts that deliver borate and condensed polyphosphates. Borate and condensed polyphosphate likewise privilege post-impact steps that yield ribonucleosides, ribonucleotides, and RNA .

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Categories: Talks

Hubble Images a Peculiar Spiral

Astronomy News - Sat, 03/05/2025 - 18:40
Explore Hubble

2 min read

Hubble Images a Peculiar Spiral This NASA/ESA Hubble Space Telescope image features a peculiar spiral galaxy called Arp 184 or NGC 1961. ESA/Hubble & NASA, J. Dalcanton, R. J. Foley (UC Santa Cruz), C. Kilpatrick

A beautiful but skewed spiral galaxy dazzles in this NASA/ESA Hubble Space Telescope image. The galaxy, called Arp 184 or NGC 1961, sits about 190 million light-years away from Earth in the constellation Camelopardalis (The Giraffe).

The name Arp 184 comes from the Atlas of Peculiar Galaxies compiled by astronomer Halton Arp in 1966. It holds 338 galaxies that are oddly shaped and tend to be neither entirely elliptical nor entirely spiral-shaped. Many of the galaxies are in the process of interacting with other galaxies, while others are dwarf galaxies without well-defined structures. Arp 184 earned its spot in the catalog thanks to its single broad, star-speckled spiral arm that appears to stretch toward us. The galaxy’s far side sports a few wisps of gas and stars, but it lacks a similarly impressive spiral arm.

This Hubble image combines data from three Snapshot observing programs, which are short observations that slotted into time gaps between other proposals. One of the three programs targeted Arp 184 for its peculiar appearance. This program surveyed galaxies listed in the Atlas of Peculiar Galaxies as well as A Catalogue of Southern Peculiar Galaxies and Associations, a similar catalog compiled by Halton Arp and Barry Madore.

The remaining two Snapshot programs looked at the aftermath of fleeting astronomical events like supernovae and tidal disruption events — like when a supermassive black hole rips a star apart after it wanders too closely. Since Arp 184 hosted four known supernovae in the past three decades, it is a rich target for a supernova hunt.

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Media Contact:

Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight CenterGreenbelt, MD

Share Details Last Updated May 02, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms Keep Exploring Discover More Topics From Hubble Hubble Space Telescope

Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.


Hubble’s Galaxies


Tracing the Growth of Galaxies


Reshaping Our Cosmic View: Hubble Science Highlights

AI scientist ‘team’ joins the search for extraterrestrial life

Astronomy News - Sat, 03/05/2025 - 18:39

Nature, Published online: 02 May 2025; doi:10.1038/d41586-025-01364-w

The collaborative system generated more than 100 hypotheses relating to the origins of life in the Universe.

Dark energy bombshell sparks race to find a new model of the universe

Astronomy News - Sat, 03/05/2025 - 18:38

‘Shocking’ results from a major astronomical study have raised doubts about the standard model of cosmology, forcing scientists to consider new ways of understanding dark energy and gravity

Searching for dark photons in the Sun’s atmosphere

Astronomy News - Fri, 02/05/2025 - 11:24

Nature, Published online: 02 May 2025; doi:10.1038/d41586-025-01335-1

Satellite observations of solar radiation have narrowed down the possible properties of dark photons — a proposed dark-matter particle.

FLAMINGO: combining kinetic SZ effect and galaxy-galaxy lensing measurements to gauge the impact of feedback on large-scale structure

Recent IoA Publications - Fri, 02/05/2025 - 11:18
arXiv:2410.19905v2 Announce Type: replace Abstract: Energetic feedback processes associated with accreting supermassive black holes can expel gas from massive haloes and significantly alter various measures of clustering on ~Mpc scales, potentially biasing the values of cosmological parameters inferred from analyses of large-scale structure (LSS) if not modelled accurately. Here we use the state-of-the-art FLAMINGO suite of cosmological hydrodynamical simulations to gauge the impact of feedback on large-scale structure by comparing to Planck + ACT stacking measurements of the kinetic Sunyaev-Zel'dovich (kSZ) effect of SDSS BOSS galaxies. We make careful like-with-like comparisons to the observations, aided by high precision KiDS and DES galaxy-galaxy lensing measurements of the BOSS galaxies to inform the selection of the simulated galaxies. In qualitative agreement with several recent studies using dark matter only simulations corrected for baryonic effects, we find that the kSZ effect measurements prefer stronger feedback than predicted by simulations which have been calibrated to reproduce the gas fractions of low redshift X-ray-selected groups and clusters. We find that the increased feedback can help to reduce the so-called S8 tension between the observed and CMB-predicted clustering on small scales as probed by cosmic shear (although at the expense of agreement with the X-ray group measurements). However, the increased feedback is only marginally effective at reducing the reported offsets between the predicted and observed clustering as probed by the thermal SZ (tSZ) effect power spectrum and tSZ effect--weak lensing cross-spectrum, both of which are sensitive to higher halo masses than cosmic shear.

FLAMINGO: combining kinetic SZ effect and galaxy-galaxy lensing measurements to gauge the impact of feedback on large-scale structure

Galaxy Evolution and AGN - Fri, 02/05/2025 - 11:18
arXiv:2410.19905v2 Announce Type: replace Abstract: Energetic feedback processes associated with accreting supermassive black holes can expel gas from massive haloes and significantly alter various measures of clustering on ~Mpc scales, potentially biasing the values of cosmological parameters inferred from analyses of large-scale structure (LSS) if not modelled accurately. Here we use the state-of-the-art FLAMINGO suite of cosmological hydrodynamical simulations to gauge the impact of feedback on large-scale structure by comparing to Planck + ACT stacking measurements of the kinetic Sunyaev-Zel'dovich (kSZ) effect of SDSS BOSS galaxies. We make careful like-with-like comparisons to the observations, aided by high precision KiDS and DES galaxy-galaxy lensing measurements of the BOSS galaxies to inform the selection of the simulated galaxies. In qualitative agreement with several recent studies using dark matter only simulations corrected for baryonic effects, we find that the kSZ effect measurements prefer stronger feedback than predicted by simulations which have been calibrated to reproduce the gas fractions of low redshift X-ray-selected groups and clusters. We find that the increased feedback can help to reduce the so-called S8 tension between the observed and CMB-predicted clustering on small scales as probed by cosmic shear (although at the expense of agreement with the X-ray group measurements). However, the increased feedback is only marginally effective at reducing the reported offsets between the predicted and observed clustering as probed by the thermal SZ (tSZ) effect power spectrum and tSZ effect--weak lensing cross-spectrum, both of which are sensitive to higher halo masses than cosmic shear.

FLAMINGO: combining kinetic SZ effect and galaxy-galaxy lensing measurements to gauge the impact of feedback on large-scale structure

Cosmology and Fundamental physics - Fri, 02/05/2025 - 11:18
arXiv:2410.19905v2 Announce Type: replace Abstract: Energetic feedback processes associated with accreting supermassive black holes can expel gas from massive haloes and significantly alter various measures of clustering on ~Mpc scales, potentially biasing the values of cosmological parameters inferred from analyses of large-scale structure (LSS) if not modelled accurately. Here we use the state-of-the-art FLAMINGO suite of cosmological hydrodynamical simulations to gauge the impact of feedback on large-scale structure by comparing to Planck + ACT stacking measurements of the kinetic Sunyaev-Zel'dovich (kSZ) effect of SDSS BOSS galaxies. We make careful like-with-like comparisons to the observations, aided by high precision KiDS and DES galaxy-galaxy lensing measurements of the BOSS galaxies to inform the selection of the simulated galaxies. In qualitative agreement with several recent studies using dark matter only simulations corrected for baryonic effects, we find that the kSZ effect measurements prefer stronger feedback than predicted by simulations which have been calibrated to reproduce the gas fractions of low redshift X-ray-selected groups and clusters. We find that the increased feedback can help to reduce the so-called S8 tension between the observed and CMB-predicted clustering on small scales as probed by cosmic shear (although at the expense of agreement with the X-ray group measurements). However, the increased feedback is only marginally effective at reducing the reported offsets between the predicted and observed clustering as probed by the thermal SZ (tSZ) effect power spectrum and tSZ effect--weak lensing cross-spectrum, both of which are sensitive to higher halo masses than cosmic shear.

exoALMA VII: Benchmarking Hydrodynamics and Radiative Transfer Codes

Planetary systems - Fri, 02/05/2025 - 11:14
arXiv:2504.18643v2 Announce Type: replace Abstract: Forward modeling is often used to interpret substructures observed in protoplanetary disks. To ensure the robustness and consistency of the current forward modeling approach from the community, we conducted a systematic comparison of various hydrodynamics and radiative transfer codes. Using four grid-based hydrodynamics codes (FARGO3D, Idefix, Athena++, PLUTO) and a smoothed particle hydrodynamics code (Phantom), we simulated a protoplanetary disk with an embedded giant planet. We then used two radiative transfer codes (mcfost, RADMC-3D) to calculate disk temperatures and create synthetic 12CO cubes. Finally, we retrieved the location of the planet from the synthetic cubes using DISCMINER. We found strong consistency between the hydrodynamics codes, particularly in the density and velocity perturbations associated with planet-driven spirals. We also found a good agreement between the two radiative transfer codes: the disk temperature in mcfost and RADMC-3D models agrees within $\lesssim 3~\%$ everywhere in the domain. In synthetic $^{12}$CO channel maps, this results in brightness temperature differences within $\pm1.5$ K in all our models. This good agreement ensures consistent retrieval of planet's radial/azimuthal location with only a few % of scatter, with velocity perturbations varying $\lesssim 20~\%$ among the models. Notably, while the planet-opened gap is shallower in the Phantom simulation, we found that this does not impact the planet location retrieval. In summary, our results demonstrate that any combination of the tested hydrodynamics and radiative transfer codes can be used to reliably model and interpret planet-driven kinematic perturbations.

exoALMA VII: Benchmarking Hydrodynamics and Radiative Transfer Codes

Recent IoA Publications - Fri, 02/05/2025 - 11:14
arXiv:2504.18643v2 Announce Type: replace Abstract: Forward modeling is often used to interpret substructures observed in protoplanetary disks. To ensure the robustness and consistency of the current forward modeling approach from the community, we conducted a systematic comparison of various hydrodynamics and radiative transfer codes. Using four grid-based hydrodynamics codes (FARGO3D, Idefix, Athena++, PLUTO) and a smoothed particle hydrodynamics code (Phantom), we simulated a protoplanetary disk with an embedded giant planet. We then used two radiative transfer codes (mcfost, RADMC-3D) to calculate disk temperatures and create synthetic 12CO cubes. Finally, we retrieved the location of the planet from the synthetic cubes using DISCMINER. We found strong consistency between the hydrodynamics codes, particularly in the density and velocity perturbations associated with planet-driven spirals. We also found a good agreement between the two radiative transfer codes: the disk temperature in mcfost and RADMC-3D models agrees within $\lesssim 3~\%$ everywhere in the domain. In synthetic $^{12}$CO channel maps, this results in brightness temperature differences within $\pm1.5$ K in all our models. This good agreement ensures consistent retrieval of planet's radial/azimuthal location with only a few % of scatter, with velocity perturbations varying $\lesssim 20~\%$ among the models. Notably, while the planet-opened gap is shallower in the Phantom simulation, we found that this does not impact the planet location retrieval. In summary, our results demonstrate that any combination of the tested hydrodynamics and radiative transfer codes can be used to reliably model and interpret planet-driven kinematic perturbations.

Tue 06 May 13:15: The Oxygen Valve on Hydrogen Escape Since the Great Oxidation Event

IoA Institute of Astronomy Talk Lists - Fri, 02/05/2025 - 10:55
The Oxygen Valve on Hydrogen Escape Since the Great Oxidation Event

The Great Oxidation Event (GOE) was a 200 Myr transition circa 2.4 billion years ago that converted the Earth’s anoxic atmosphere to one where molecular oxygen (O2) was abundant. This rise in O2 is thought to have substantially throttled hydrogen (H) escape and the associated water (H2O) loss. In this study we use WACCM6 , a three-dimensional Earth System Model to simulate Earth’s atmosphere and predict the diffusion-limited escape rate of hydrogen due to varying O2 concentrations based on atmospheric estimations from the GOE onward, ranging between 0.1 PAL to 150 PAL , where PAL is the present atmospheric level of 21 % by volume. O2 indirectly acts as a control valve on the amount of hydrogen atoms reaching the homopause in the simulations: less O2 leads to decreased O3 densities, reducing local temperatures by up to 5 K, which increases H2O freeze-drying. For the considered scenarios, the maximum difference in the total H mixing ratio at the homopause and calculated diffusion-limited escape rates is a factor of 3.2 and 4.7, respectively, with the prescribed CH4 mixing ratio setting a minimum diffusion escape rate of ≈ 2 × 10^10 mol H/yr. These numerical predictions support geological evidence that the majority of Earth’s hydrogen escape occurred prior to the GOE .

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Tue 06 May 13:15: The Oxygen Valve on Hydrogen Escape Since the Great Oxidation Event

Next Wednesday Seminars - Fri, 02/05/2025 - 10:55
The Oxygen Valve on Hydrogen Escape Since the Great Oxidation Event

The Great Oxidation Event (GOE) was a 200 Myr transition circa 2.4 billion years ago that converted the Earth’s anoxic atmosphere to one where molecular oxygen (O2) was abundant. This rise in O2 is thought to have substantially throttled hydrogen (H) escape and the associated water (H2O) loss. In this study we use WACCM6 , a three-dimensional Earth System Model to simulate Earth’s atmosphere and predict the diffusion-limited escape rate of hydrogen due to varying O2 concentrations based on atmospheric estimations from the GOE onward, ranging between 0.1 PAL to 150 PAL , where PAL is the present atmospheric level of 21 % by volume. O2 indirectly acts as a control valve on the amount of hydrogen atoms reaching the homopause in the simulations: less O2 leads to decreased O3 densities, reducing local temperatures by up to 5 K, which increases H2O freeze-drying. For the considered scenarios, the maximum difference in the total H mixing ratio at the homopause and calculated diffusion-limited escape rates is a factor of 3.2 and 4.7, respectively, with the prescribed CH4 mixing ratio setting a minimum diffusion escape rate of ≈ 2 × 10^10 mol H/yr. These numerical predictions support geological evidence that the majority of Earth’s hydrogen escape occurred prior to the GOE .

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Categories: Talks

NASA’s Chandra Diagnoses Cause of Fracture in Galactic “Bone”

Astronomy News - Fri, 02/05/2025 - 10:28
X-ray: NASA/CXC/Northwestern Univ./F. Yusef-Zadeh et al; Radio: NRF/SARAO/MeerKat; Image Processing: NASA/CXC/SAO/N. Wolk

Astronomers have discovered a likely explanation for a fracture in a huge cosmic “bone” in the Milky Way galaxy, using NASA’s Chandra X-ray Observatory and radio telescopes.

The bone appears to have been struck by a fast-moving, rapidly spinning neutron star, or pulsar. Neutron stars are the densest known stars and form from the collapse and explosion of massive stars. They often receive a powerful kick from these explosions, sending them away from the explosion’s location at high speeds.

Enormous structures resembling bones or snakes are found near the center of the galaxy. These elongated formations are seen in radio waves and are threaded by magnetic fields running parallel to them. The radio waves are caused by energized particles spiraling along the magnetic fields.

X-ray: NASA/CXC/Northwestern Univ./F. Yusef-Zadeh et al; Radio: NRF/SARAO/MeerKat; Image Processing: NASA/CXC/SAO/N. Wolk

This new image shows one of these cosmic “bones” called G359.13142-0.20005 (G359.13 for short), with X-ray data from Chandra (colored blue) and radio data from the MeerKAT radio array in South Africa (colored gray). Researchers also refer to G359.13 as the Snake.

Examining this image closely reveals the presence of a break, or fracture, in the otherwise continuous length of G359.13 seen in the image. The combined X-ray and radio data provides clues to the cause of this fracture.

Astronomers have now discovered an X-ray and radio source at the location of the fracture, using the data from Chandra and MeerKAT and the National Science Foundation’s Very Large Array. A likely pulsar responsible for these radio and X-ray signals is labeled. A possible extra source of X-rays located near the pulsar may come from electrons and positrons (the anti-matter counterparts to electrons) that have been accelerated to high energies.

The researchers think the pulsar likely caused the fracture by smashing into G359.13 at a speed between one million and two million miles per hour. This collision distorted the magnetic field in the bone, causing the radio signal to also become warped.

At about 230 light-years long, G359.13 is one of the longest and brightest of these structures in the Milky Way. To put this into context, there are more than 800 stars within that distance from Earth. G359.13 is located about 26,000 light-years from Earth, near the center of the Milky Way.

A paper describing these results appeared in the May 2024 issue of the Monthly Notices of the Royal Astronomical Society and is available here. The authors of the study are Farhad Yusuf-Zadeh (Northwestern University), Jun-Hui Zhao (Center for Astrophysics | Harvard & Smithsonian), Rick Arendt (University of Maryland, Baltimore County), Mark Wardle (Macquarie University, Australia), Craig Heinke (University of Alberta), Marc Royster (College of the Sequoias, California), Cornelia Lang (University of Iowa), and Joseph Michail (Northwestern).

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.

Learn More

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 two composite images of a long, thin, cosmic structure. With the structure’s vertical orientation, seemingly fragile dimensions, and pale grey color against the blackness of space, the images resemble medical X-rays of a long, thin, bone. The main image shows the structure in its entirety. The inset image is an annotated close-up highlighting an apparent fracture in the bone-like structure.

The structure, called G359.13, or “The Snake”, is a Galactic Center Filament. These filament formations are threaded by parallel magnetic fields, and spiraling, energized particles. The particles cause radio waves, which can be detected by radio arrays, in this case by the MeerKAT array in South Africa.

In the first composite image, the largely straight filament stretches from the top to the bottom of the vertical frame. At each end of the grey filament is a hazy grey cloud. The only color in the image is neon blue, found in a few specks which dot the blackness surrounding the structure. The blue represents X-rays seen by NASA’s Chandra X-ray Observatory.

In the annotated close-up, one such speck appears to be interacting with the structure itself. This is a fast-moving, rapidly spinning neutron star, otherwise known as a pulsar. Astronomers believe that this pulsar has struck the filament halfway down its length, distorting the magnetic field and radio signal.

In both images, this distortion resembles a small break, or spur, in the bone-like filament.

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

NASA’s SPHEREx Space Telescope Begins Capturing Entire Sky

Astronomy News - Fri, 02/05/2025 - 10:28

6 min read

Preparations for Next Moonwalk Simulations Underway (and Underwater) NASA’s SPHEREx mission is observing the entire sky in 102 infrared colors, or wavelengths of light not visible to the human eye. This image shows a section of sky in one wavelength (3.29 microns), revealing a cloud of dust made of a molecule similar to soot or smoke.NASA/JPL-Caltech This image from NASA’s SPHEREx shows the same region of space in a different infrared wavelength (0.98 microns), but the dust cloud is no longer visible. The molecules that compose the dust — polycyclic aromatic hydrocarbons — do not radiate light in this color.NASA/JPL-Caltech

After weeks of preparation, the space observatory has begun its science mission, taking about 3,600 unique images per day to create a map of the cosmos like no other.

Launched on March 11, NASA’s SPHEREx space observatory has spent the last six weeks undergoing checkouts, calibrations, and other activities to ensure it is working as it should. Now it’s mapping the entire sky — not just a large part of it — to chart the positions of hundreds of millions of galaxies in 3D to answer some big questions about the universe. On May 1, the spacecraft began regular science operations, which consist of taking about 3,600 images per day for the next two years to provide new insights about the origins of the universe, galaxies, and the ingredients for life in the Milky Way.

This video shows SPHEREx’s field of view as it scans across one section of sky inside the Large Magellanic Cloud, with rainbow colors representing the infrared wavelengths the telescope’s detectors see. The view from one detector array moves from purple to green, followed by the second array’s view, which changes from yellow to red. The images are looped four times. NASA/JPL-Caltech

“Thanks to the hard work of teams across NASA, industry, and academia that built this mission, SPHEREx is operating just as we’d expected and will produce maps of the full sky unlike any we’ve had before,” said Shawn Domagal-Goldman, acting director of the Astrophysics Division at NASA Headquarters in Washington. “This new observatory is adding to the suite of space-based astrophysics survey missions leading up to the launch of NASA’s Nancy Grace Roman Space Telescope. Together with these other missions, SPHEREx will play a key role in answering the big questions about the universe we tackle at NASA every day.”

From its perch in Earth orbit, SPHEREx peers into the darkness, pointing away from the planet and the Sun. The observatory will complete more than 11,000 orbits over its 25 months of planned survey operations, circling Earth about 14½ times a day. It orbits Earth from north to south, passing over the poles, and each day it takes images along one circular strip of the sky. As the days pass and the planet moves around the Sun, SPHEREx’s field of view shifts as well so that after six months, the observatory will have looked out into space in every direction.

When SPHEREx takes a picture of the sky, the light is sent to six detectors that each produces a unique image capturing different wavelengths of light. These groups of six images are called an exposure, and SPHEREx takes about 600 exposures per day. When it’s done with one exposure, the whole observatory shifts position — the mirrors and detectors don’t move as they do on some other telescopes. Rather than using thrusters, SPHEREx relies on a system of reaction wheels, which spin inside the spacecraft to control its orientation.

Hundreds of thousands of SPHEREx’s images will be digitally woven together to create four all-sky maps in two years. By mapping the entire sky, the mission will provide new insights about what happened in the first fraction of a second after the big bang. In that brief instant, an event called cosmic inflation caused the universe to expand a trillion-trillionfold.

“We’re going to study what happened on the smallest size scales in the universe’s earliest moments by looking at the modern universe on the largest scales,” said Jim Fanson, the mission’s project manager at NASA’s Jet Propulsion Laboratory in Southern California. “I think there’s a poetic arc to that.”

Cosmic inflation subtly influenced the distribution of matter in the universe, and clues about how such an event could happen are written into the positions of galaxies across the universe. When cosmic inflation began, the universe was smaller than the size of an atom, but the properties of that early universe were stretched out and influence what we see today. No other known event or process involves the amount of energy that would have been required to drive cosmic inflation, so studying it presents a unique opportunity to understand more deeply how our universe works.

“Some of us have been working toward this goal for 12 years,” said Jamie Bock, the mission’s principal investigator at Caltech and JPL. “The performance of the instrument is as good as we hoped. That means we’re going to be able to do all the amazing science we planned on and perhaps even get some unexpected discoveries.”

Color Field

The SPHEREx observatory won’t be the first to map the entire sky, but it will be the first to do so in so many colors. It observes 102 wavelengths, or colors, of infrared light, which are undetectable to the human eye. Through a technique called spectroscopy, the telescope separates the light into wavelengths — much like a prism creates a rainbow from sunlight — revealing all kinds of information about cosmic sources.

For example, spectroscopy can be harnessed to determine the distance to a faraway galaxy, information that can be used to turn a 2D map of those galaxies into a 3D one. The technique will also enable the mission to measure the collective glow from all the galaxies that ever existed and see how that glow has changed over cosmic time.

And spectroscopy can reveal the composition of objects. Using this capability, the mission is searching for water and other key ingredients for life in these systems in our galaxy. It’s thought that the water in Earth’s oceans originated as frozen water molecules attached to dust in the interstellar cloud where the Sun formed.

The SPHEREx mission will make over 9 million observations of interstellar clouds in the Milky Way, mapping these materials across the galaxy and helping scientists understand how different conditions can affect the chemistry that produced many of the compounds found on Earth today.

More About SPHEREx

The SPHEREx mission is managed by JPL for the agency’s Astrophysics Division within the Science Mission Directorate at NASA Headquarters. BAE Systems in Boulder, Colorado, built the telescope and the spacecraft bus. The science analysis of the SPHEREx data will be conducted by a team of scientists located at 10 institutions in the U.S., two in South Korea, and one in Taiwan. Caltech in Pasadena managed and integrated the instrument. The mission’s principal investigator is based at Caltech with a joint JPL appointment. Data will be processed and archived at IPAC at Caltech. The SPHEREx dataset will be publicly available at the NASA-IPAC Infrared Science Archive. Caltech manages JPL for NASA.

For more about SPHEREx, visit:

https://science.nasa.gov/mission/spherex/

News Media Contact

Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov

2025-063

Share Details Last Updated May 01, 2025 Related Terms Explore More 4 min read NASA’s Chandra Diagnoses Cause of Fracture in Galactic “Bone” Article 5 hours ago 3 min read The Universe’s Brightest Lights Have Some Dark Origins

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May’s Night Sky Notes: How Do We Find Exoplanets?

Astronomy News - Thu, 01/05/2025 - 11:36

4 min read

May’s Night Sky Notes: How Do We Find Exoplanets?

Astronomers have been trying to discover evidence that worlds exist around stars other than our Sun since the 19th century. By the mid-1990s, technology finally caught up with the desire for discovery and led to the first discovery of a planet orbiting another sun-like star, Pegasi 51b. Why did it take so long to discover these distant worlds, and what techniques do astronomers use to find them?

The Transit Method A planet passing in front of its parent star creates a drop in the star’s apparent brightness, called a transit. Exoplanet Watch participants can look for transits in data from ground-based telescopes, helping scientists refine measurements of the length of a planet’s orbit around its star. Credit: NASA’s Ames Research Center

One of the most famous exoplanet detection methods is the transit method, used by Kepler and other observatories. When a planet crosses in front of its host star, the light from the star dips slightly in brightness. Scientists can confirm a planet orbits its host star by repeatedly detecting these incredibly tiny dips in brightness using sensitive instruments. If you can imagine trying to detect the dip in light from a massive searchlight when an ant crosses in front of it, at a distance of tens of miles away, you can begin to see how difficult it can be to spot a planet from light-years away! Another drawback to the transit method is that the distant solar system must be at a favorable angle to our point of view here on Earth – if the distant system’s angle is just slightly askew, there will be no transits. Even in our solar system, a transit is very rare. For example, there were two transits of Venus visible across our Sun from Earth in this century. But the next time Venus transits the Sun as seen from Earth will be in the year 2117 – more than a century from the 2012 transit, even though Venus will have completed nearly 150 orbits around the Sun by then!

The Wobble Method As a planet orbits a star, the star wobbles. This causes a change in the appearance of the star’s spectrum called Doppler shift. Because the change in wavelength is directly related to relative speed, astronomers can use Doppler shift to calculate exactly how fast an object is moving toward or away from us. Astronomers can also track the Doppler shift of a star over time to estimate the mass of the planet orbiting it. NASA, ESA, CSA, Leah Hustak (STScI)

Spotting the Doppler shift of a star’s spectra was used to find Pegasi 51b, the first planet detected around a Sun-like star. This technique is called the radial velocity or “wobble” method. Astronomers split up the visible light emitted by a star into a rainbow. These spectra, and gaps between the normally smooth bands of light, help determine the elements that make up the star. However, if there is a planet orbiting the star, it causes the star to wobble ever so slightly back and forth. This will, in turn, cause the lines within the spectra to shift ever so slightly towards the blue and red ends of the spectrum as the star wobbles slightly away and towards us. This is caused by the blue and red shifts of the star’s light. By carefully measuring the amount of shift in the star’s spectra, astronomers can determine the size of the object pulling on the host star and if the companion is indeed a planet. By tracking the variation in this periodic shift of the spectra, they can also determine the time it takes the planet to orbit its parent star.

Direct Imaging

Finally, exoplanets can be revealed by directly imaging them, such as this image of four planets found orbiting the star HR 8799! Space telescopes use instruments called coronagraphs to block the bright light from the host star and capture the dim light from planets. The Hubble Space Telescope has captured images of giant planets orbiting a few nearby systems, and the James Webb Space Telescope has only improved on these observations by uncovering more details, such as the colors and spectra of exoplanet atmospheres, temperatures, detecting potential exomoons, and even scanning atmospheres for potential biosignatures!

NASA’s James Webb Space Telescope has provided the clearest look in the infrared yet at the iconic multi-planet system HR 8799. The closest planet to the star, HR 8799 e, orbits 1.5 billion miles from its star, which in our solar system would be located between the orbit of Saturn and Neptune. The furthest, HR 8799 b, orbits around 6.3 billion miles from the star, more than twice Neptune’s orbital distance. Colors are applied to filters from Webb’s NIRCam (Near-Infrared Camera), revealing their intrinsic differences. A star symbol marks the location of the host star HR 8799, whose light has been blocked by the coronagraph. In this image, the color blue is assigned to 4.1 micron light, green to 4.3 micron light, and red to the 4.6 micron light. NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI)

You can find more information and activities on NASA’s Exoplanets page, such as the Eyes on Exoplanets browser-based program, The Exoplaneteers, and some of the latest exoplanet news. Lastly, you can find more resources in our News & Resources section, including a clever demo on how astronomers use the wobble method to detect planets! 

The future of exoplanet discovery is only just beginning, promising rich rewards in humanity’s understanding of our place in the Universe, where we are from, and if there is life elsewhere in our cosmos.

Originally posted by Dave Prosper: July 2015
Last Updated by Kat Troche: April 2025

StratLearn-z: Improved photo-$z$ estimation from spectroscopic data subject to selection effects

Galaxy Evolution and AGN - Thu, 01/05/2025 - 11:29
arXiv:2409.20379v2 Announce Type: replace Abstract: A precise measurement of photometric redshifts (photo-z) is key for the success of modern photometric galaxy surveys. Machine learning (ML) methods show great promise in this context, but suffer from covariate shift (CS) in training sets due to selection bias where interesting sources are underrepresented, and the corresponding ML models show poor generalisation properties. We present an application of the StratLearn method to the estimation of photo-z, validating against simulations where we enforce the presence of CS to different degrees. StratLearn is a statistically principled approach that relies on splitting the source and target datasets into strata based on estimated propensity scores (i.e. the probability for an object to be in the source set given its observed covariates). After stratification, two conditional density estimators are fit separately to each stratum, then combined via a weighted average. We benchmark our results against the GPz algorithm, quantifying the performance of the two codes with a set of metrics. Our results show that the StratLearn-z metrics are only marginally affected by the presence of CS, while GPz shows a significant degradation of performance in the photo-z prediction for fainter objects. For the strongest CS scenario, StratLearn-z yields a reduced fraction of catastrophic errors, a factor of 2 improvement for the RMSE and one order of magnitude improvement on the bias. We also assess the quality of the conditional redshift estimates with the probability integral transform (PIT). The PIT distribution obtained from StratLearn-z features fat fewer outliers and is symmetric, i.e. the predictions appear to be centered around the true redshift value, despite showing a conservative estimation of the spread of the conditional redshift distributions. Our julia implementation of the method is available at https://github.com/chiaramoretti/StratLearn-z.

StratLearn-z: Improved photo-$z$ estimation from spectroscopic data subject to selection effects

Recent IoA Publications - Thu, 01/05/2025 - 11:29
arXiv:2409.20379v2 Announce Type: replace Abstract: A precise measurement of photometric redshifts (photo-z) is key for the success of modern photometric galaxy surveys. Machine learning (ML) methods show great promise in this context, but suffer from covariate shift (CS) in training sets due to selection bias where interesting sources are underrepresented, and the corresponding ML models show poor generalisation properties. We present an application of the StratLearn method to the estimation of photo-z, validating against simulations where we enforce the presence of CS to different degrees. StratLearn is a statistically principled approach that relies on splitting the source and target datasets into strata based on estimated propensity scores (i.e. the probability for an object to be in the source set given its observed covariates). After stratification, two conditional density estimators are fit separately to each stratum, then combined via a weighted average. We benchmark our results against the GPz algorithm, quantifying the performance of the two codes with a set of metrics. Our results show that the StratLearn-z metrics are only marginally affected by the presence of CS, while GPz shows a significant degradation of performance in the photo-z prediction for fainter objects. For the strongest CS scenario, StratLearn-z yields a reduced fraction of catastrophic errors, a factor of 2 improvement for the RMSE and one order of magnitude improvement on the bias. We also assess the quality of the conditional redshift estimates with the probability integral transform (PIT). The PIT distribution obtained from StratLearn-z features fat fewer outliers and is symmetric, i.e. the predictions appear to be centered around the true redshift value, despite showing a conservative estimation of the spread of the conditional redshift distributions. Our julia implementation of the method is available at https://github.com/chiaramoretti/StratLearn-z.

"Oh FUors where art thou": A search for long-lasting YSO outbursts hiding in infrared surveys

Planetary systems - Thu, 01/05/2025 - 11:09
arXiv:2504.21237v1 Announce Type: new Abstract: Long-lasting episodes of high accretion can strongly impact stellar and planetary formation. However, the universality of these events during the formation of young stellar objects (YSOs) is still under debate. Accurate statistics of strong outbursts (FUors), are necessary to understand the role of episodic accretion bursts. In this work, we search for a population of FUors that may have gone undetected in the past because they either a) went into outburst before the start of modern monitoring surveys and are now slowly fading back into quiescence or b) are slow-rising outbursts that would not commonly be classified as candidate FUors. We hypothesise that the light curves of these outbursts should be well fitted by linear models with negative (declining) or positive (rising) slopes. The analysis of the infrared light curves and photometry of $\sim$99000 YSO candidates from SPICY yields 717 candidate FUors. Infrared spectroscopy of 20 candidates, from both the literature and obtained by our group, confirms that 18 YSOs are going through long-term outbursts and identifies two evolved sources as contaminants. The number of candidate FUors combined with previously measured values of the frequency of FUor outbursts, yield average outburst decay times that are 2.5 times longer than the rise times. In addition, a population of outbursts with rise timescales between 2000 and 5000 days must exist to obtain our observed number of YSOs with positive slopes. Finally, we estimate a mean burst lifetime of between 45 and 100 years.

"Oh FUors where art thou": A search for long-lasting YSO outbursts hiding in infrared surveys

Recent IoA Publications - Thu, 01/05/2025 - 11:09
arXiv:2504.21237v1 Announce Type: new Abstract: Long-lasting episodes of high accretion can strongly impact stellar and planetary formation. However, the universality of these events during the formation of young stellar objects (YSOs) is still under debate. Accurate statistics of strong outbursts (FUors), are necessary to understand the role of episodic accretion bursts. In this work, we search for a population of FUors that may have gone undetected in the past because they either a) went into outburst before the start of modern monitoring surveys and are now slowly fading back into quiescence or b) are slow-rising outbursts that would not commonly be classified as candidate FUors. We hypothesise that the light curves of these outbursts should be well fitted by linear models with negative (declining) or positive (rising) slopes. The analysis of the infrared light curves and photometry of $\sim$99000 YSO candidates from SPICY yields 717 candidate FUors. Infrared spectroscopy of 20 candidates, from both the literature and obtained by our group, confirms that 18 YSOs are going through long-term outbursts and identifies two evolved sources as contaminants. The number of candidate FUors combined with previously measured values of the frequency of FUor outbursts, yield average outburst decay times that are 2.5 times longer than the rise times. In addition, a population of outbursts with rise timescales between 2000 and 5000 days must exist to obtain our observed number of YSOs with positive slopes. Finally, we estimate a mean burst lifetime of between 45 and 100 years.