Thu 15 May 16:00: The different merger and evolutionary histories of the Milky Way and Andromeda (M31)
The Milky Way experienced a major satellite merger 10 Gyr ago which altered, but did not destroy, the early high-alpha disk and created both an accreted and an in situ inner halo. The low-alpha disk that formed subsequently became bar-unstable 8 Gyr ago, creating the b/p bulge that also contains the inner high-alpha disk stars. M31 experienced a similar major satellite merger 3 Gyr ago which greatly heated and mixed the pre-existing high-metallicity disk, and also caused a massive inflow of gas and the formation of a dynamically hot secondary inner disk. Such a merger is consistent with the wide-spread star formation event 2-4 Gyr ago seen in disk colour-magnitude diagrams, and with the major substructures and metal-rich stars in the inner halo of M31 , when comparing photometric and recent spectroscopic data with available models. The merged satellite must have had a broad metallicity distribution and would have been the third most massive galaxy in the Local Group before the merger.
- Speaker: Ortwin Gerhard, MPE (Garching)
- Thursday 15 May 2025, 16:00-17:00
- Venue: Hoyle Lecture Theatre, Institute of Astronomy.
- Series: Institute of Astronomy Colloquia; organiser: .
Was a famous supernova an alien invader from another galaxy?
Wed 14 May 13:15: Noise from Above: Determining the Impact of Starlink's Unintended Electromagnetic Radiation on REACH
21-cm cosmology experiments have opened new frontiers in our quest to explore the early universe. However, the rapid expansion of satellite constellations in Low Earth Orbit (LEO) poses a significant threat. SpaceX’s Starlink is particularly concerning due to unintended electromagnetic radiation (UEMR) generated by its hardware and onboard electronic subsystems, as reported by observatories such as the Low-Frequency Array (LOFAR). These emissions could contaminate observations of the faint 21-cm signal, already buried beneath foreground emissions and radio frequency interference (RFI). The Radio Experiment for the Analysis of Cosmic Hydrogen (REACH) is a low-frequency radio telescope based in the Karoo radio reserve, South Africa, designed to detect the global 21-cm signal from Cosmic Dawn. In this talk, I will present my ongoing work assessing the extent to which Starlink impacts REACH . My approach combines orbital trajectory simulations using Two-Line Element (TLE) catalogues with geometric constraints to identify Starlink flyovers within REACH ’s field of view. These are cross-referenced with power spectral density (PSD) measurements to search for correlations indicating UEMR , including Doppler shift analysis. I conclude by outlining plans to automate this process and how this work contributes to broader efforts to safeguard radio astronomy from satellite interference.
- Speaker: Gabriella Rajpoot / Cavendish Laboratory
- Wednesday 14 May 2025, 13:15-13:40
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: .
Wed 14 May 13:15: Noise from Above: Determining the Impact of Starlink's Unintended Electromagnetic Radiation on REACH
21-cm cosmology experiments have opened new frontiers in our quest to explore the early universe. However, the rapid expansion of satellite constellations in Low Earth Orbit (LEO) poses a significant threat. SpaceX’s Starlink is particularly concerning due to unintended electromagnetic radiation (UEMR) generated by its hardware and onboard electronic subsystems, as reported by observatories such as the Low-Frequency Array (LOFAR). These emissions could contaminate observations of the faint 21-cm signal, already buried beneath foreground emissions and radio frequency interference (RFI). The Radio Experiment for the Analysis of Cosmic Hydrogen (REACH) is a low-frequency radio telescope based in the Karoo radio reserve, South Africa, designed to detect the global 21-cm signal from Cosmic Dawn. In this talk, I will present my ongoing work assessing the extent to which Starlink impacts REACH . My approach combines orbital trajectory simulations using Two-Line Element (TLE) catalogues with geometric constraints to identify Starlink flyovers within REACH ’s field of view. These are cross-referenced with power spectral density (PSD) measurements to search for correlations indicating UEMR , including Doppler shift analysis. I conclude by outlining plans to automate this process and how this work contributes to broader efforts to safeguard radio astronomy from satellite interference.
- Speaker: Gabriella Rajpoot / Cavendish Laboratory
- Wednesday 14 May 2025, 13:15-13:40
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: .
Thu 22 May 16:00: The effect of binary mass transfer on the late evolution, death, and afterlife of massive stars
Gravitational-wave observations have revealed the population of stellar remnants from a new angle. Yet their stellar progenitors remain uncertain, in particular in the case of black holes. At least a fraction of these stars is believed to form in isolated binary systems. In this talk, I will discuss how binary mass transfer affects the late evolution and final fate of massive stars. The focus will be on stars that transfer their outer layers to a companion star and become binary-stripped. Binary-stripped stars develop systematically different core structures compared to single stars. I will discuss consequences for supernovae, black hole formation, and gravitational-wave observations.
- Speaker: Eva laplace, University of Leuven, Belgium
- Thursday 22 May 2025, 16:00-17:00
- Venue: Hoyle Lecture Theatre, Institute of Astronomy.
- Series: Institute of Astronomy Colloquia; organiser: ag2017.
Thu 22 May 16:00: The effect of binary mass transfer on the late evolution, death, and afterlife of massive stars
Gravitational-wave observations have revealed the population of stellar remnants from a new angle. Yet their stellar progenitors remain uncertain, in particular in the case of black holes. At least a fraction of these stars is believed to form in isolated binary systems. In this talk, I will discuss how binary mass transfer affects the late evolution and final fate of massive stars. The focus will be on stars that transfer their outer layers to a companion star and become binary-stripped. Binary-stripped stars develop systematically different core structures compared to single stars. I will discuss consequences for supernovae, black hole formation, and gravitational-wave observations.
- Speaker: Eva laplace, University of Leuven, Belgium
- Thursday 22 May 2025, 16:00-17:00
- Venue: Hoyle Lecture Theatre, Institute of Astronomy.
- Series: Institute of Astronomy Colloquia; organiser: ag2017.
GOTO065054+593624: a 8.5 mag amplitude dwarf nova identified in real time via Kilonova Seekers
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On the Double: Two Luminous Flares from the Nearby Tidal Disruption Event ASASSN-22ci (AT2022dbl) and Connections to Repeating TDE Candidates
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A data-driven approach for star formation parameterization using symbolic regression
A data-driven approach for star formation parameterization using symbolic regression
Star formation and accretion rates within 500 pc as traced by Gaia DR3 XP spectra
Star formation and accretion rates within 500 pc as traced by Gaia DR3 XP spectra
Euclid preparation. The impact of redshift interlopers on the two-point correlation function analysis
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Failed Soviet probe will soon crash to Earth – and we don't know where
NASA Telescopes Tune Into a Black Hole Prelude, Fugue
NASA released three new pieces of cosmic sound Thursday that are associated with the densest and darkest members of our universe: black holes. These scientific productions are sonifications — or translations into sound — of data collected by NASA telescopes in space including the Chandra X-ray Observatory, James Webb Space Telescope, and Imaging X-ray Polarimetry Explorer (IXPE).
This trio of sonifications represents different aspects of black holes and black hole evolution. WR124 is an extremely bright, short-lived massive star known as a Wolf-Rayet that may collapse into a black hole in the future. SS 433 is a binary, or double system, containing a star like our Sun in orbit with either a neutron star or a black hole. The galaxy Centaurus A has an enormous black hole in its center that is sending a booming jet across the entire length of the galaxy. Data from Chandra and other telescopes were translated through a process called “sonification” into sounds and notes.This new trio of sonifications represents different aspects of black holes. Black holes are neither static nor monolithic. They evolve over time, and are found in a range of sizes and environments.
WR 124 Credit: X-ray: NASA/CXC/SAO; Infrared: (Herschel) ESA/NASA/Caltech, (Spitzer) NASA/JPL/Caltech, (WISE) NASA/JPL/Caltech; Infrared: NASA/ESA/CSA/STScI/Webb ERO Production Team; Image processing: NASA/CXC/SAO/J. Major; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)The first movement is a prelude to the potential birth of a black hole. WR124 is an extremely bright, short-lived massive star known as a Wolf-Rayet at a distance of about 28,000 light-years from Earth. These stars fling their outer layers out into space, creating spectacular arrangements seen in an image in infrared light from the Webb telescope. In the sonification of WR124, this nebula is heard as flutes and the background stars as bells. At the center of WR124, where the scan begins before moving outward, is a hot core of the star that may explode as a supernova and potentially collapse and leave behind a black hole in its wake. As the scan moves from the center outward, X-ray sources detected by Chandra are translated into harp sounds. Data from NASA’s James Webb Space Telescope is heard as metallic bell-like sounds, while the light of the central star is mapped to produce the descending scream-like sound at the beginning. The piece is rounded out by strings playing additional data from the infrared telescopic trio of ESA’s (European Space Agency’s) Herschel Space Telescope, NASA’s retired Spitzer Space Telescope, and NASA’s retired Wide Image Survey Explorer (WISE) as chords.
SS 433 Credit: X-ray: (IXPE): NASA/MSFC/IXPE; (Chandra): NASA/CXC/SAO; (XMM): ESA/XMM-Newton; IR: NASA/JPL/Caltech/WISE; Radio: NRAO/AUI/NSF/VLA/B. Saxton. (IR/Radio image created with data from M. Goss, et al.); Image Processing/compositing: NASA/CXC/SAO/N. Wolk & K. Arcand; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)In the second movement of this black hole composition, listeners can explore a duet. SS 433 is a binary, or double, system about 18,000 light-years away that sings out in X-rays. The two members of SS 433 include a star like our Sun in orbit around a much heavier partner, either a neutron star or a black hole. This orbital dance causes undulations in X-rays that Chandra, IXPE, and ESA’s XMM-Newton telescopes are tuned into. These X-ray notes have been combined with radio and infrared data to provide a backdrop for this celestial waltz. The nebula in radio waves resembles a drifting manatee, and the scan sweeps across from right to left. Light towards the top of the image is mapped to higher-pitch sound, with radio, infrared, and X-ray light mapped to low, medium, and high pitch ranges. Bright background stars are played as water-drop sounds, and the location of the binary system is heard as a plucked sound, pulsing to match the fluctuations due to the orbital dance.
Centarus A Credit: X-ray: (Chandra) NASA/CXC/SAO, (IXPE) NASA/MSFC; Optical: ESO; Image Processing: NASA/CXC/SAO/K. Arcand, J. Major, and J. Schmidt; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)The third and final movement of the black hole-themed sonifications crescendos with a distant galaxy known as Centaurus A, about 12 million light-years away from Earth. At the center of Centaurus A is an enormous black hole that is sending a booming jet across the entire length of the galaxy. Sweeping around clockwise from the top of the image, the scan encounters Chandra’s X-rays and plays them as single-note wind chimes. X-ray light from IXPE is heard as a continuous range of frequencies, producing a wind-like sound. Visible light data from the European Southern Observatory’s MPG telescope shows the galaxy’s stars that are mapped to string instruments including foreground and background objects as plucked strings.
For more NASA sonifications and information about the project, visit https://chandra.si.edu/sound/
These sonifications were led by the Chandra X-ray Center (CXC), with support from NASA’s Marshall Space Flight Center and NASA’s Universe of Learning program, which is part of the NASA Science Activation program. The collaboration was driven by visualization scientist Kimberly Arcand (CXC), astrophysicist Matt Russo, and musician Andrew Santaguida (both of the SYSTEM Sounds project), along with consultant Christine Malec.
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts. NASA’s Universe of Learning materials are based upon work supported by NASA under cooperative agreement award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and NASA’s Jet Propulsion Laboratory.
The agency’s IXPE is a collaboration between NASA and the Italian Space Agency with partners and science collaborators in 12 countries. The IXPE mission is led by Marshall. BAE Systems, Inc., headquartered in Falls Church, Virginia, manages spacecraft operations together with the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder.
To learn more about NASA’s space telescopes, visit:
https://science.nasa.gov/universe
Read more from NASA’s Chandra X-ray ObservatoryLearn more about the Chandra X-ray Observatory and its mission here:
Visual DescriptionThis release features three sonifications related to black holes, presented as soundtracks to short videos. Each sonification video features a composite image representing a different aspect of the life of a black hole. These images are visualizations of data collected by NASA telescopes. During each video, a line sweeps through the image. When the line encounters a visual element, it is translated into sound according to parameters established by visualization scientist Kimberly Arcand, astrophysicist Matt Russo, musician Andrew Santaguida, and consultant Christine Malec.
The first sonification features WR124, an extremely bright, massive star. Here, the star is shown in a short-lived phase preceding the possible creation of a black hole. At the center of the composite image is the large gleaming star in white and pale blue. The star sits at the heart of a mottled pink and gold cloud, its long diffraction spikes extending to the outer edges. Also residing in the cloud are other large gleaming stars, glowing hot-pink dots, and tiny specks of blue and white light. In this sonification, the sound activation line is an ever-expanding circle which starts in the center of the massive star and continues to grow until it exits the frame.
The second sonification features SS 433, a binary star system at the center of a supernova remnant known as the Manatee Nebula. Visually, the translucent, blobby teal nebula does, indeed, resemble a bulbous walrus or manatee, floating in a red haze packed with distant specs of light. Inside the nebula is a violet streak, a blue streak, and a large bright dot. The dot, represented by a plucking sound in the sonification, is the binary system at the heart of the nebula. In this sonification, the vertical activation line begins at our right edge of the frame, and sweeps across the image before exiting at our left.
The third and final sonification features Centaurus A, a distant galaxy with an enormous black hole emitting a long jet of high-energy particles. The black hole sits at the center of the composite image, represented by a brilliant white light. A dark, grainy, oblong cloud cuts diagonally across the black hole from our lower left toward our upper right. A large, faint, translucent blue cloud stretches from our upper left to our lower right. And the long, thin jet, also in translucent blue, extends from the black hole at the center toward the upper lefthand corner. In this sonification, the activation line rotates around the image like the hand of a clock. It begins at the twelve o’clock position, and sweeps clockwise around the image.
News Media ContactMegan 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
- Chandra X-Ray Observatory
- Black Holes
- Galaxies, Stars, & Black Holes
- IXPE (Imaging X-ray Polarimetry Explorer)
- Marshall Astrophysics
- Marshall Science Research & Projects
- Marshall Space Flight Center
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Tue 20 May 11:15: A 21-cm Cosmologist’s Journey: From Cambridge to North America and Back Again
In this talk, I’ll take you on a whistle-stop tour of my journey in 21-cm cosmology – from my PhD days in Cambridge to fellowship and research scientist positions in the USA and Canada. I’ll discuss the significance of 21-cm cosmology in understanding the Universe’s first billion years and describe key projects I’ve worked on, including the SKA , HERA, EDGES , and REACH . Along the way, I’ll share some personal highlights from my time in North America, including adventures in national parks and snow sports.
- Speaker: Dr. Peter Sims (University of Cambridge)
- Tuesday 20 May 2025, 11:15-12:00
- Venue: Martin Ryle Seminar Room, Kavli Institute.
- Series: Hills Coffee Talks; organiser: Charles Walker.