Mon 03 Mar 13:40: Strong lensing and stellar kinematics of cluster galaxies
As the most massive gravitationally bound structures in the Universe, galaxy clusters frequently act as strong gravitational lenses. Strong lensing (SL) enables us to reconstruct the total mass distribution of a cluster with extreme accuracy, providing insights into the physical properties of dark matter and its interplay with baryons. SL models are also crucial for studying magnified high-redshift sources and measuring cosmological parameters from observed time delays between lensed variable sources. However, the accuracy of SL models is limited by parametric degeneracy, which hinders the reconstruction of the mass distribution of cluster members. This degeneracy can be resolved using independent information from their stellar kinematics. After a general introduction to SL by galaxy clusters, I will present how we leveraged deep MUSE /VLT observations of SL clusters to build a large catalogue of accurate stellar velocity dispersion measurements of early-type member galaxies. These measurements serve as the foundation for calibrating new scaling relations that describe their structure in a set of highly accurate SL models and for comparisons with cosmological hydrodynamical simulations of galaxy clusters, aimed at testing the ΛCDM paradigm.
- Speaker: Giovanni Granata / University of Portsmouth
- Monday 03 March 2025, 13:40-14:05
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: .
Mon 03 Mar 13:15: Metal enrichment of a dusty star-forming galaxies at the EoR with JWST/INIRSpec IFS
With the recent discovery of quiescent galaxies at z>3, studying of dusty star-forming galaxies at high redshift became more vital than ever, as they are thought to be precursors of quiescent galaxies. However, until the launch of JWST , studying the rest-frame of optical emission of these sources at redshifts higher than 3 was out of reach of astronomers, often solely relying on the ALMA observations of their FIR emission lines. In this talk, I will present one of the first JWST /NIRSpec IFS data of a massive dusty star-forming galaxy at the Epoch of Reionisation. COS -3018, is a unique UV bright galaxy (LUV>2 L*) at z~6.8, previously only observed using ALMA ([CII]158 microns, [OIII] 88 microns), VLT X -Shooter (Lyman-alpha) and HST broadband photometry. Furthermore, this galaxy has a large amount of dust (log Mdust =10.7 Msol) and an excess of [OIII]88micron emission suggesting that this might be an AGN or has non-standard ISM conditions such as AGN . I will present deep high-resolution JWST /NIRSpec IFS observations of rest-frame UV and optical continuum and emission lines, in combination with deep ALMA [CII] and [OIII]88micron observations and NIR Cam photometry. Using the deep and unique NIR Spec IFS (PRISM+R2700) observations, I will show the ISM conditions in this unique galaxy: excitation conditions (extreme star formation or AGN ?), metallicity gradient, location of dust obscured (from ALMA high resolution observations) and unobscured star formation. Finally, I will answer the question: What is driving such an extreme production of dust in this galaxy and UV luminosity in this galaxy?
- Speaker: Jan Scholtz / IoA
- Monday 03 March 2025, 13:15-13:40
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: .
The asteroid hits and near-misses you never hear about
Mon 03 Mar 14:00: Exoplanets and the Road to the Radius Valley
The observed population of small, close-in exoplanets is bifurcated into two distinct types by the so-called ‘radius valley’. In this talk, I will discuss the atmospheric escape processes that may affect such planets and finally lead to the radius gap being carved out, specifically X-ray/EUV photoevaporation, core-powered mass loss, and boil-off. The latter process is an extreme mass loss mechanism that is triggered by protoplanetary disc dispersal and may have lasting impacts on the population of small exoplanets.
- Speaker: James Rogers (Institute of Astronomy, Cambridge)
- Monday 03 March 2025, 14:00-15:00
- Venue: MR14 DAMTP and online.
- Series: DAMTP Astrophysics Seminars; organiser: Loren E. Held.
Touchdown! Carrying NASA Science, Firefly’s Blue Ghost Lands on Moon
Carrying a suite of NASA science and technology, Firefly Aerospace’s Blue Ghost Mission 1 successfully landed at 3:34 a.m. EST on Sunday near a volcanic feature called Mons Latreille within Mare Crisium, a more than 300-mile-wide basin located in the northeast quadrant of the Moon’s near side.
The Blue Ghost lander is in an upright and stable configuration, and the successful Moon delivery is part of NASA’s CLPS (Commercial Lunar Payload Services) initiative and Artemis campaign. This is the first CLPS delivery for Firefly, and their first Moon landing.
The 10 NASA science and technology instruments aboard the lander will operate on the lunar surface for approximately one lunar day, or about 14 Earth days.
“This incredible achievement demonstrates how NASA and American companies are leading the way in space exploration for the benefit of all,” said NASA acting Administrator Janet Petro. “We have already learned many lessons – and the technological and science demonstrations onboard Firefly’s Blue Ghost Mission 1 will improve our ability to not only discover more science, but to ensure the safety of our spacecraft instruments for future human exploration – both in the short term and long term.”
Since launching from NASA’s Kennedy Space Center in Florida on Jan. 15, Blue Ghost traveled more than 2.8 million miles, downlinked more than 27 GB of data, and supported several science operations. This included signal tracking from the Global Navigation Satellite System (GNSS) at a record-breaking distance of 246,000 miles with the Lunar GNSS Receiver Experiment payload – showing NASA can use the same positioning systems on Earth when at the Moon. Science conducted during the journey also included radiation tolerant computing through the Van Allen Belts with the Radiation-Tolerant Computer System payload and measurements of magnetic field changes in space with the Lunar Magnetotelluric Sounder payload.
“The science and technology we send to the Moon now helps prepare the way for future NASA exploration and long-term human presence to inspire the world for generations to come,” said Nicky Fox, associate administrator for science at NASA Headquarters in Washington. “We’re sending these payloads by working with American companies – which supports a growing lunar economy.”
During surface operations, the NASA instruments will test and demonstrate lunar subsurface drilling technology, regolith sample collection capabilities, global navigation satellite system abilities, radiation tolerant computing, and lunar dust mitigation methods. The data captured will benefit humanity by providing insights into how space weather and other cosmic forces impact Earth.
Before payload operations conclude, teams will aim to capture imagery of the lunar sunset and how lunar dust reacts to solar influences during lunar dusk conditions, a phenomenon first documented by former NASA astronaut Eugene Cernan on Apollo 17. Following the lunar sunset, the lander will operate for several hours into the lunar night.
“On behalf of our entire team, I want to thank NASA for entrusting Firefly as their lunar delivery provider,” said Jason Kim, CEO of Firefly Aerospace. “Blue Ghost’s successful Moon landing has laid the groundwork for the future of commercial exploration across cislunar space. We’re now looking forward to more than 14 days of surface operations to unlock even more science data that will have a substantial impact on future missions to the Moon and Mars.”
To date, five vendors have been awarded 11 lunar deliveries under CLPS and are sending more than 50 instruments to various locations on the Moon, including the lunar South Pole. Existing CLPS contracts are indefinite-delivery, indefinite-quantity contracts with a cumulative maximum contract value of $2.6 billion through 2028.
Learn more about NASA’s CLPS initiative at:
-end-
Amber Jacobson / Karen Fox
Headquarters, Washington
202-358-1600
amber.c.jacobson@nasa.gov / karen.c.fox@nasa.gov
Natalia Riusech / Nilufar Ramji
Johnson Space Center, Houston
281-483-5111
nataila.s.riusech@nasa.gov / nilufar.ramji@nasa.gov
Antonia Jaramillo
Kennedy Space Center, Florida
321-501-8425
antonia.jaramillobotero@nasa.gov
NASA set to launch SPHEREx space telescope to scan entire sky
Fri 23 May 11:30: Title to be confirmed
Abstract not available
- Speaker: Guido Roberts-Borsani (UCL)
- Friday 23 May 2025, 11:30-12:30
- Venue: Ryle Seminar Room, KICC + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Infrared space telescope will probe ‘inflation’ after Big Bang
How to see every planet in the solar system at once this week
NASA’s Hubble Provides Bird’s-Eye View of Andromeda Galaxy’s Ecosystem
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NASA, ESA, Alessandro Savino (UC Berkeley), Joseph DePasquale (STScI), Akira Fujii DSS2
Located 2.5 million light-years away, the majestic Andromeda galaxy appears to the naked eye as a faint, spindle-shaped object roughly the angular size of the full Moon. What backyard observers don’t see is a swarm of nearly three dozen small satellite galaxies circling the Andromeda galaxy, like bees around a hive.
These satellite galaxies represent a rambunctious galactic “ecosystem” that NASA’s Hubble Space Telescope is studying in unprecedented detail. This ambitious Hubble Treasury Program used observations from more than a whopping 1,000 Hubble orbits. Hubble’s optical stability, clarity, and efficiency made this ambitious survey possible. This work included building a precise 3D mapping of all the dwarf galaxies buzzing around Andromeda and reconstructing how efficiently they formed new stars over the nearly 14 billion years of the universe’s lifetime.
This is a wide-angle view of the distribution of known satellite galaxies orbiting the large Andromeda galaxy (M31), located 2.5 million light-years away. The Hubble Space Telescope was used to study the entire population of 36 mini-galaxies circled in yellow. Andromeda is the bright spindle-shaped object at image center. All the dwarf galaxies seem to be confined to a plane, all orbiting in the same direction. The wide view is from ground-based photography. Hubble’s optical stability, clarity, and efficiency made this ambitious survey possible. Hubble close up snapshots of four dwarf galaxies are on image right. The most prominent dwarf galaxy is M32 (NGC 221), a compact ellipsoidal galaxy that might be the remnant core of a larger galaxy that collided with Andromeda a few billion years ago. NASA, ESA, Alessandro Savino (UC Berkeley), Joseph DePasquale (STScI), Akira Fujii DSS2
In the study published in The Astrophysical Journal, Hubble reveals a markedly different ecosystem from the smaller number of satellite galaxies that circle our Milky Way. This offers forensic clues as to how our Milky Way galaxy and Andromeda have evolved differently over billions of years. Our Milky Way has been relatively placid. But it looks like Andromeda has had a more dynamic history, which was probably affected by a major merger with another big galaxy a few billion years ago. This encounter, and the fact that Andromeda is as much as twice as massive as our Milky Way, could explain its plentiful and diverse dwarf galaxy population.
Surveying the Milky Way’s entire satellite system in such a comprehensive way is very challenging because we are embedded inside our galaxy. Nor can it be accomplished for other large galaxies because they are too far away to study the small satellite galaxies in much detail. The nearest galaxy of comparable mass to the Milky Way beyond Andromeda is M81, at nearly 12 million light-years.
This bird’s-eye view of Andromeda’s satellite system allows us to decipher what drives the evolution of these small galaxies. “We see that the duration for which the satellites can continue forming new stars really depends on how massive they are and on how close they are to the Andromeda galaxy,” said lead author Alessandro Savino of the University of California at Berkeley. “It is a clear indication of how small-galaxy growth is disturbed by the influence of a massive galaxy like Andromeda.”
“Everything scattered in the Andromeda system is very asymmetric and perturbed. It does appear that something significant happened not too long ago,” said principal investigator Daniel Weisz of the University of California at Berkeley. “There’s always a tendency to use what we understand in our own galaxy to extrapolate more generally to the other galaxies in the universe. There’s always been concerns about whether what we are learning in the Milky Way applies more broadly to other galaxies. Or is there more diversity among external galaxies? Do they have similar properties? Our work has shown that low-mass galaxies in other ecosystems have followed different evolutionary paths than what we know from the Milky Way satellite galaxies.”
For example, half of the Andromeda satellite galaxies all seem to be confined to a plane, all orbiting in the same direction. “That’s weird. It was actually a total surprise to find the satellites in that configuration and we still don’t fully understand why they appear that way,” said Weisz.
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The brightest companion galaxy to Andromeda is Messier 32 (M32). This is a compact ellipsoidal galaxy that might just be the remnant core of a larger galaxy that collided with Andromeda a few billion years ago. After being gravitationally stripped of gas and some stars, it continued along its orbit. Galaxy M32 contains older stars, but there is evidence it had a flurry of star formation a few billion years ago. In addition to M32, there seems to be a unique population of dwarf galaxies in Andromeda not seen in the Milky Way. They formed most of their stars very early on, but then they didn’t stop. They kept forming stars out of a reservoir of gas at a very low rate for a much longer time.
“Star formation really continued to much later times, which is not at all what you would expect for these dwarf galaxies,” continued Savino. “This doesn’t appear in computer simulations. No one knows what to make of that so far.”
“We do find that there is a lot of diversity that needs to be explained in the Andromeda satellite system,” added Weisz. “The way things come together matters a lot in understanding this galaxy’s history.”
Hubble is providing the first set of imaging where astronomers measure the motions of the dwarf galaxies. In another five years Hubble or NASA’s James Webb Space Telescope will be able to get the second set of observations, allowing astronomers to do a dynamical reconstruction for all 36 of the dwarf galaxies, which will help astronomers to rewind the motions of the entire Andromeda ecosystem billions of years into the past.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
Explore MoreNASA’s Hubble Traces Hidden History of Andromeda Galaxy
Hubble’s High-Definition Panoramic View of the Andromeda Galaxy
Explore the Night Sky: Messier 31
Hubble’s Galaxies
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Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, Maryland
Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
Science Contact:
Alessandro Savino
University of California, Berkeley, California
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Reshaping Our Cosmic View: Hubble Science Highlights
Our Galaxy’s central black hole puts on a fireworks show
Nature, Published online: 27 February 2025; doi:10.1038/d41586-025-00578-2
The James Webb Space Telescope uncovered repeated flares from the supermassive object called Sagittarius A*.Fri 07 Mar 11:30: Simulating supermassive black holes: from event horizon to cosmic web and back again
Abstract not available
- Speaker: Martin Bourne (Hertfordshire)
- Friday 07 March 2025, 11:30-12:30
- Venue: Ryle Seminar Room, KICC + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Variability of Central Stars of Planetary Nebulae with the Zwicky Transient Facility. II. Long-Timescale Variables including Wide Binary and Late Thermal Pulse Candidates
Variability of Central Stars of Planetary Nebulae with the Zwicky Transient Facility. II. Long-Timescale Variables including Wide Binary and Late Thermal Pulse Candidates
Glacial isostatic adjustment reveals Mars’s interior viscosity structure
Nature, Published online: 26 February 2025; doi:10.1038/s41586-024-08565-9
Emplacement of the north polar cap of Mars is investigated by combining viscoelastic deformation calculations and observations, showing that it formed over the last 1.7–12.0 Myr atop a stiff lithosphere and high-viscosity mantle (1022 Pa s), and that glacial isostatic adjustment could be further constrained.Meet the ice-hunting robots headed for the Moon right now
Nature, Published online: 27 February 2025; doi:10.1038/d41586-025-00597-z
Two US probes launched today, one laden with a drill and a hopper looking for lunar water.Seeing the Outer Edge of the Infant Type Ia Supernova 2024epr in the Optical and Near Infrared
Seeing the Outer Edge of the Infant Type Ia Supernova 2024epr in the Optical and Near Infrared
Mon 19 May 15:00: Title to be confirmed
Abstract not available
- Speaker: Adrien La Posta (University of Oxford)
- Monday 19 May 2025, 15:00-16:00
- Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
- Series: Cosmology Lunch; organiser: Louis Legrand.
NASA: New Study on Why Mars is Red Supports Potentially Habitable Past
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)A new international study partially funded by NASA on how Mars got its iconic red color adds to evidence that Mars had a cool but wet and potentially habitable climate in its ancient past.
Mosaic of the Valles Marineris hemisphere of Mars projected into point perspective, a view similar to that which one would see from a spacecraft. The distance is 2500 kilometers from the surface of the planet, with the scale being .6km/pixel. The mosaic is composed of 102 Viking Orbiter images of Mars. The center of the scene (lat -8, long 78) shows the entire Valles Marineris canyon system, over 2000 kilometers long and up to 8 kilometers deep, extending form Noctis Labyrinthus, the arcuate system of graben to the west, to the chaotic terrain to the east. Many huge ancient river channels begin from the chaotic terrain from north-central canyons and run north. The three Tharsis volcanoes (dark red spots), each about 25 kilometers high, are visible to the west. South of Valles Marineris is very ancient terrain covered by many impact craters.NASA
The current atmosphere of Mars is too cold and thin to support liquid water, an essential ingredient for life, on its surface for lengthy periods. However, various NASA and international missions have found evidence that water was abundant on the Martian surface billions of years ago during a more clement era, such as features that resemble dried-up rivers and lakes, and minerals that only form in the presence of liquid water.
Adding to this evidence, results from a study published February 25 in the journal Nature Communications suggest that the water-rich iron mineral ferrihydrite may be the main culprit behind Mars’ reddish dust. Martian dust is known to be a hodgepodge of different minerals, including iron oxides, and this new study suggests one of those iron oxides, ferrihydrite, is the reason for the planet’s color.
The finding offers a tantalizing clue to Mars’ wetter and potentially more habitable past because ferrihydrite forms in the presence of cool water, and at lower temperatures than other previously considered minerals, like hematite. This suggests that Mars may have had an environment capable of sustaining liquid water before it transitioned from a wet to a dry environment billions of years ago.
“The fundamental question of why Mars is red has been considered for hundreds if not for thousands of years,” said lead author Adam Valantinas, a postdoctoral fellow at Brown University, Providence, Rhode Island, who started the work as a Ph.D. student at the University of Bern, Switzerland. “From our analysis, we believe ferrihydrite is everywhere in the dust and also probably in the rock formations, as well. We’re not the first to consider ferrihydrite as the reason for why Mars is red, but we can now better test this using observational data and novel laboratory methods to essentially make a Martian dust in the lab.”
Laboratory sample showing simulated Martian dust. The ochre color is characteristic of iron-rich ferrihydrite, a mineral that provides crucial insights into ancient water activity and environmental conditions on Mars. The fine-powder mixture consists of ferrihydrite and ground basalt with particles less than one micrometer in size (1/100th diameter of a human hair) (Sample scale: 1 inch across).Adam Valantinas
“These new findings point to a potentially habitable past for Mars and highlight the value of coordinated research between NASA and its international partners when exploring fundamental questions about our solar system and the future of space exploration,” said Geronimo Villanueva, the Associate Director for Strategic Science of the Solar System Exploration Division at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and co-author of this study.
The researchers analyzed data from multiple Mars missions, combining orbital observations from instruments on NASA’s Mars Reconnaissance Orbiter, ESA’s (the European Space Agency) Mars Express and Trace Gas Orbiter with ground-level measurements from NASA rovers like Curiosity, Pathfinder, and Opportunity. Instruments on the orbiters and rovers provided detailed spectral data of the planet’s dusty surface. These findings were then compared to laboratory experiments, where the team tested how light interacts with ferrihydrite particles and other minerals under simulated Martian conditions.
“What we want to understand is the ancient Martian climate, the chemical processes on Mars — not only ancient — but also present,” said Valantinas. “Then there’s the habitability question: Was there ever life? To understand that, you need to understand the conditions that were present during the time of this mineral’s formation. What we know from this study is the evidence points to ferrihydrite forming and for that to happen there must have been conditions where oxygen from air or other sources and water can react with iron. Those conditions were very different from today’s dry, cold environment. As Martian winds spread this dust everywhere, it created the planet’s iconic red appearance.”
Whether the team’s proposed formation model is correct could be definitively tested after samples from Mars are delivered to Earth for analysis.
“The study really is a door-opening opportunity,” said Jack Mustard of Brown University, a senior author on the study. “It gives us a better chance to apply principles of mineral formation and conditions to tap back in time. What’s even more important though is the return of the samples from Mars that are being collected right now by the Perseverance rover. When we get those back, we can actually check and see if this is right.”
Part of the spectral measurements were performed at NASA’s Reflectance Experiment Laboratory (RELAB) at Brown University. RELAB is supported by NASA’s Planetary Science Enabling Facilities program, part of the Planetary Science Division of NASA’s Science Mission Directorate at NASA Headquarters in Washington.
NASA Goddard Space Flight Center, Greenbelt, Maryland
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