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arXiv:2507.06206v1 Announce Type: new Abstract: HD 135344 AB is a young visual binary system that is best known for the protoplanetary disk around the secondary star. The circumstellar environment of the A0-type primary star, on the other hand, is already depleted. HD 135344 A is therefore an ideal target for the exploration of recently formed giant planets because it is not obscured by dust. We searched for and characterized substellar companions to HD 135344 A down to separations of about 10 au. We observed HD 135344 A with VLT/SPHERE in the $H23$ and $K12$ bands and obtained $YJ$ and $YJH$ spectroscopy. In addition, we carried out VLTI/GRAVITY observations for the further astrometric and spectroscopic confirmation of a detected companion. We discovered a close-in young giant planet, HD 135344 Ab, with a mass of about 10 $M_\mathrm{J}$. The multi-epoch astrometry confirms the bound nature based on common parallax and common proper motion. This firmly rules out the scenario of a non-stationary background star. The semi-major axis of the planetary orbit is approximately 15-20 au, and the photometry is consistent with that of a mid L-type object. The inferred atmospheric and bulk parameters further confirm the young and planetary nature of the companion. HD 135344 Ab is one of the youngest directly imaged planets that has fully formed and orbits on Solar System scales. It is a valuable target for studying the early evolution and atmosphere of a giant planet that could have formed in the vicinity of the snowline.

In 2025, the University of Cambridge celebrates a significant milestone: the 30th anniversary of the undergraduate astronomy course at the Institute of Astronomy. First introduced in the Michaelmas Term of 1995, the course offers students a unique opportunity to explore the universe through rigorous academic training...

In 2025, the University of Cambridge celebrates a significant milestone: the 30th anniversary of the undergraduate astronomy course at the Institute of Astronomy. First introduced in the Michaelmas Term of 1995, the course offers students a unique opportunity to explore the universe through rigorous academic training...

Nature, Published online: 08 July 2025; doi:10.1038/d41586-025-02070-3

Expanding human influence in outer space will require an ethical compass that is more expansive than the one conventionally used.

ESA/Hubble & NASA, J. Bally, M. Robberto

NASA’s Hubble Space Telescope captured a bright variable star, V 372 Orionis, and its companion in this festive image in this image released on Jan. 27, 2023. The pair lie in the Orion Nebula, a colossal region of star formation roughly 1,450 light-years from Earth.

V 372 Orionis is a particular type of variable star known as an Orion Variable. These young stars experience some tempestuous moods and growing pains, which are visible to astronomers as irregular variations in luminosity. Orion Variables are often associated with diffuse nebulae, and V 372 Orionis is no exception; the patchy gas and dust of the Orion Nebula pervade this scene.

Text credit: European Space Agency (ESA)

Image credit: ESA/Hubble & NASA, J. Bally, M. Robberto

Double black hole mergers in nuclear star clusters: eccentricities, spins, masses, and the growth of massive seeds

We investigate the formation of intermediate-mass black holes (IMBHs) through hierarchical mergers of stellar-origin black holes (BHs), as well as BH mergers formed dynamically in nuclear star clusters. Using a semi-analytical approach that incorporates probabilistic, mass-function–dependent double-BH (DBH) pairing, binary–single encounters, and a mass-ratio–dependent prescription for energy dissipation in hardening binaries, we find that IMB Hs with masses of order 10²–10⁴ M⊙ can be formed solely through hierarchical mergers on timescales of a few hundred Myr to a few Gyr. Clusters with escape velocities ≳ 400 km s⁻¹ inevitably form high-mass IMB Hs. The spin distribution of IMB Hs with masses ≳ 10³ M⊙ is strongly clustered at χ ≈ 0.15, while for lower masses it peaks at χ ≈ 0.7. Eccentric mergers are more frequent for equal-mass binaries containing first- and second-generation BHs. Metal-rich, young, dense clusters can produce up to 20 of their DBH mergers with eccentricity ≥ 0.1 at 10 Hz, and ~ 2–9 of all in-cluster mergers form at > 10 Hz. Nuclear star clusters are therefore promising environments for the formation of highly eccentric DBH mergers, detectable with current gravitational-wave detectors. Clusters of extreme mass (∼ 10⁸ M⊙) and density (∼ 10⁸ M⊙ pc⁻³) can have about half of their DBH mergers with primary masses ≥ 100 M⊙. The fraction of in-cluster mergers increases rapidly with increasing escape velocity, approaching unity for Vesc ≳ 200 km s⁻¹. The cosmological DBH merger rate from nuclear clusters varies from ≲ 0.01 to 1 Gpc⁻³ yr⁻¹, where the large uncertainties stem from cluster initial conditions, number-density distributions, and the redshift evolution of nucleated galaxies.

• Speaker: Debatri Chattopadhyay
• Wednesday 09 July 2025, 13:15-13:45
• Venue: Hoyle Lecture theatre + Zoom .
• Series: Institute of Astronomy Seminars; organiser: Cristiano Longarini.

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Double black hole mergers in nuclear star clusters: eccentricities, spins, masses, and the growth of massive seeds

We investigate the formation of intermediate-mass black holes (IMBHs) through hierarchical mergers of stellar-origin black holes (BHs), as well as BH mergers formed dynamically in nuclear star clusters. Using a semi-analytical approach that incorporates probabilistic, mass-function–dependent double-BH (DBH) pairing, binary–single encounters, and a mass-ratio–dependent prescription for energy dissipation in hardening binaries, we find that IMB Hs with masses of order 10²–10⁴ M⊙ can be formed solely through hierarchical mergers on timescales of a few hundred Myr to a few Gyr. Clusters with escape velocities ≳ 400 km s⁻¹ inevitably form high-mass IMB Hs. The spin distribution of IMB Hs with masses ≳ 10³ M⊙ is strongly clustered at χ ≈ 0.15, while for lower masses it peaks at χ ≈ 0.7. Eccentric mergers are more frequent for equal-mass binaries containing first- and second-generation BHs. Metal-rich, young, dense clusters can produce up to 20 of their DBH mergers with eccentricity ≥ 0.1 at 10 Hz, and ~ 2–9 of all in-cluster mergers form at > 10 Hz. Nuclear star clusters are therefore promising environments for the formation of highly eccentric DBH mergers, detectable with current gravitational-wave detectors. Clusters of extreme mass (∼ 10⁸ M⊙) and density (∼ 10⁸ M⊙ pc⁻³) can have about half of their DBH mergers with primary masses ≥ 100 M⊙. The fraction of in-cluster mergers increases rapidly with increasing escape velocity, approaching unity for Vesc ≳ 200 km s⁻¹. The cosmological DBH merger rate from nuclear clusters varies from ≲ 0.01 to 1 Gpc⁻³ yr⁻¹, where the large uncertainties stem from cluster initial conditions, number-density distributions, and the redshift evolution of nucleated galaxies.

• Speaker: Debatri Chattopadhyay
• Wednesday 09 July 2025, 13:15-13:45
• Venue: Hoyle Lecture theatre + Zoom .
• Series: Institute of Astronomy Seminars; organiser: Cristiano Longarini.

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Around seven asteroids or comets are thought to hit Saturn ever year, but we have never spotted one in the act. Now, it seems one astronomer may have caught the moment of impact and the hunt is on for other images to verify the discovery

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3 min read

NASA’s Hubble and Webb Telescopes Reveal Two Faces of a Star Cluster Duo A vast network of stars, gas, and dust is strung among a duo of star clusters in this combined image from NASA’s Hubble and Webb space telescopes. Open clusters NGC 460 and NGC 456 reside in the Small Magellanic Cloud, a dwarf galaxy orbiting the Milky Way. This highly detailed 527 megapixel mosaic consists of 12 overlapping observations and includes both visible and infrared wavelengths. To view some of its incredible detail, download the 40.1 MB file and zoom in. NASA, ESA, and C. Lindberg (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America)
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A riotous expanse of gas, dust, and stars stake out the dazzling territory of a duo of star clusters in this combined image from NASA’s Hubble and Webb space telescopes.

Open clusters NGC 460 and NGC 456 reside in the Small Magellanic Cloud, a dwarf galaxy orbiting the Milky Way. Open clusters consist of anywhere from a few dozen to a few thousand young stars loosely bound together by gravity. These particular clusters are part of an extensive complex of star clusters and nebulae that are likely linked to one another. As clouds of gas collapse, stars are born. These young, hot stars expel intense stellar winds that shape the nebulae around them, carving out the clouds and triggering other collapses, which in turn give rise to more stars.

In these images, Hubble’s view captures the glowing, ionized gas as stellar radiation blows “bubbles” in the clouds of gas and dust (blue), while Webb’s infrared vision highlights the clumps and delicate filamentary structures of dust (red). In Hubble images, dust is often seen silhouetted against and blocking light, but in Webb’s view, the dust – warmed by starlight – shines with its own infrared glow. This mixture of gas and dust between the universe’s stars is known as the interstellar medium.

Hubble (ACS) Webb (NIRCAM)

This Hubble image shows a duo of open clusters, NGC 460 and NGC 456. The nebulae’s glowing gas, ionized by the radiation of nearby stars, is distinct in Hubble’s view. NASA, ESA, and C. Lindberg (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America)

In Webb’s infrared view of open clusters NGC 460 and NGC 456, dusty areas are visible as bright structures glowing red. Many background galaxies are visible, their infrared light passing through the region’s obscuring clouds of gas and dust. NASA, ESA, and C. Lindberg (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America) Hubble (ACS)Webb (NIRCAM)

This Hubble image shows a duo of open clusters, NGC 460 and NGC 456. The nebulae’s glowing gas, ionized by the radiation of nearby stars, is distinct in Hubble’s view. NASA, ESA, and C. Lindberg (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America) In Webb’s infrared view of open clusters NGC 460 and NGC 456, dusty areas are visible as bright structures glowing red. Many background galaxies are visible, their infrared light passing through the region’s obscuring clouds of gas and dust. NASA, ESA, and C. Lindberg (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America)
Hubble (ACS)
Webb (NIRCAM)

Hubble and Webb view a duo of open star clusters
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Slide to switch between Hubble and Web images. Hubble’s view captures visible light and some infrared wavelengths, while Webb’s view is exclusively infrared. The nebulae’s glowing gas, ionized by the radiation of nearby stars, is distinct in Hubble’s view. Dusty areas that appear dark in the Hubble image are visible as bright structures in the Webb image, and more background galaxies are visible since infrared light from fainter and farther galaxies can pass through the obscuring clouds of gas and dust.

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The nodules visible in these images are scenes of active star formation, with stars ranging from just one to 10 million years old. In contrast, our Sun is 4.5 billion years old. The region that holds these clusters, known as the N83-84-85 complex, is home to multiple, rare O-type stars, hot and extremely massive stars that burn hydrogen like our Sun. Astronomers estimate there are only around 20,000 O-type stars among the approximately 400 billion stars in the Milky Way.

Clouds of ionized gas dominate open cluster NGC 460 in the Hubble image (left), while tendrils of dust are on display in the Webb image (right). Together, the two images provide a more comprehensive look at the region. NASA, ESA, and C. Lindberg (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America) The Hubble image of NGC 456 (left) shows a puffy, bluish cloud of ionized gas, while the Webb image (right) displays the same cluster’s cavern-like outline of dust. NASA, ESA, and C. Lindberg (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America)

The Small Magellanic Cloud is of great interest to researchers because it is less enriched in metals than the Milky Way. Astronomers call all elements heavier than hydrogen and helium – that is, with more than two protons in the atom’s nucleus – “metals.”  This state mimics conditions in the early universe, so the Small Magellanic Cloud provides a relatively nearby laboratory to explore theories about star formation and the interstellar medium at early stages of cosmic history. With these observations of NGC 460 and NGC 456, researchers intend to study how gas flows in the region converge or divide; refine the collision history between the Small Magellanic Cloud and its fellow dwarf galaxy, the Large Magellanic Cloud; examine how bursts of star formation occur in such gravitational interactions between galaxies; and better understand the interstellar medium.

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NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

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Details Last Updated Jul 07, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms

• Hubble Space Telescope
• James Webb Space Telescope (JWST)
• Open Clusters
• Star Clusters
• Stars
• The Universe

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 Cosmic Adventure

Hubble’s Night Sky Challenge

Hubble’s 35th Anniversary

Title to be confirmed

Abstract not available

• Speaker: Michele Ginolfi (Florence)
• Friday 24 October 2025, 11:30-12:30
• Venue: Ryle Seminar Room, KICC + online.
• Series: Galaxies Discussion Group; organiser: Sandro Tacchella.

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arXiv:2507.02284v1 Announce Type: new Abstract: The Milky Way Survey of the Dark Energy Spectroscopic Instrument (DESI) has so far observed three classical dwarf spheroidal galaxies (dSphs): Draco, Sextans and Ursa Minor. Based on the observed line-of-sight velocities and metallicities of their member stars, we apply the axisymmetric Jeans Anisotropic Multi-Gaussian Expansion modeling (JAM) approach to recover their inner dark matter distributions. In particular, both the traditional single-population Jeans model and the multiple population chemodynamical model are adopted. With the chemodynamical model, we divide member stars of each dSph into metal-rich and metal-poor populations. The metal-rich populations are more centrally concentrated and dynamically colder, featuring lower velocity dispersion profiles than the metal-poor populations. We find a diversity of the inner density slopes $\gamma$ of dark matter halos, with the best constraints by single-population or chemodynamical models consistent with each other. The inner density slopes are $0.71^{+0.34}_{-0.35}$, $0.26^{+0.22}_{-0.12}$ and $0.33^{+0.20}_{-0.16}$ for Draco, Sextans and Ursa Minor, respectively. We also present the measured astrophysical J and D factors of the three dSphs. Our results indicate that the study of the dark matter content of dSphs through stellar kinematics is still subject to uncertainties behind both the methodology and the observed data, through comparisons with previous measurements and data sets.

arXiv:2507.02284v1 Announce Type: new Abstract: The Milky Way Survey of the Dark Energy Spectroscopic Instrument (DESI) has so far observed three classical dwarf spheroidal galaxies (dSphs): Draco, Sextans and Ursa Minor. Based on the observed line-of-sight velocities and metallicities of their member stars, we apply the axisymmetric Jeans Anisotropic Multi-Gaussian Expansion modeling (JAM) approach to recover their inner dark matter distributions. In particular, both the traditional single-population Jeans model and the multiple population chemodynamical model are adopted. With the chemodynamical model, we divide member stars of each dSph into metal-rich and metal-poor populations. The metal-rich populations are more centrally concentrated and dynamically colder, featuring lower velocity dispersion profiles than the metal-poor populations. We find a diversity of the inner density slopes $\gamma$ of dark matter halos, with the best constraints by single-population or chemodynamical models consistent with each other. The inner density slopes are $0.71^{+0.34}_{-0.35}$, $0.26^{+0.22}_{-0.12}$ and $0.33^{+0.20}_{-0.16}$ for Draco, Sextans and Ursa Minor, respectively. We also present the measured astrophysical J and D factors of the three dSphs. Our results indicate that the study of the dark matter content of dSphs through stellar kinematics is still subject to uncertainties behind both the methodology and the observed data, through comparisons with previous measurements and data sets.

arXiv:2507.02284v1 Announce Type: new Abstract: The Milky Way Survey of the Dark Energy Spectroscopic Instrument (DESI) has so far observed three classical dwarf spheroidal galaxies (dSphs): Draco, Sextans and Ursa Minor. Based on the observed line-of-sight velocities and metallicities of their member stars, we apply the axisymmetric Jeans Anisotropic Multi-Gaussian Expansion modeling (JAM) approach to recover their inner dark matter distributions. In particular, both the traditional single-population Jeans model and the multiple population chemodynamical model are adopted. With the chemodynamical model, we divide member stars of each dSph into metal-rich and metal-poor populations. The metal-rich populations are more centrally concentrated and dynamically colder, featuring lower velocity dispersion profiles than the metal-poor populations. We find a diversity of the inner density slopes $\gamma$ of dark matter halos, with the best constraints by single-population or chemodynamical models consistent with each other. The inner density slopes are $0.71^{+0.34}_{-0.35}$, $0.26^{+0.22}_{-0.12}$ and $0.33^{+0.20}_{-0.16}$ for Draco, Sextans and Ursa Minor, respectively. We also present the measured astrophysical J and D factors of the three dSphs. Our results indicate that the study of the dark matter content of dSphs through stellar kinematics is still subject to uncertainties behind both the methodology and the observed data, through comparisons with previous measurements and data sets.

Rocky bodies called protoplanets were thought to have formed slightly earlier in the inner solar system than those beyond the asteroid belt, but now a meteorite from the outer solar system is rewriting that view

Unveiling the shape of the ionizing spectrum of galaxies

Abstract not available

• Speaker: Anne Verhamme (University of Geneva)
• Friday 11 July 2025, 11:30-12:30
• Venue: Ryle Seminar Room, KICC + online.
• Series: Galaxies Discussion Group; organiser: Sandro Tacchella.

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Nature, Published online: 03 July 2025; doi:10.1038/d41586-025-02141-5

The comet-like body called either C/2025 N1 or 3I/ATLAS is now zipping past Jupiter.

Explore Hubble

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2 min read

Hubble Observations Give “Missing” Globular Cluster Time to Shine This NASA Hubble Space Telescope image features a dense and dazzling array of blazing stars that form globular cluster ESO 591-12. NASA, ESA, and D. Massari (INAF — Osservatorio di Astrofisica e Scienza dello Spazio); Processing: Gladys Kober (NASA/Catholic University of America)
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A previously unexplored globular cluster glitters with multicolored stars in this NASA Hubble Space Telescope image. Globular clusters like this one, called ESO 591-12 or Palomar 8, are spherical collections of tens of thousands to millions of stars tightly bound together by gravity. Globular clusters generally form early in the galaxies’ histories in regions rich in gas and dust. Since the stars form from the same cloud of gas as it collapses, they typically hover around the same age. Strewn across this image of ESO 591-12 are a number of red and blue stars. The colors indicate their temperatures; red stars are cooler, while the blue stars are hotter.

Hubble captured the data used to create this image of ESO 591-12 as part of a study intended to resolve individual stars of the entire globular cluster system of the Milky Way. Hubble revolutionized the study of globular clusters since earthbound telescopes are unable to distinguish individual stars in the compact clusters. The study is part of the Hubble Missing Globular Clusters Survey, which targets 34 confirmed Milky Way globular clusters that Hubble has yet to observe.

The program aims to provide complete observations of ages and distances for all of the Milky Way’s globular clusters and investigate fundamental properties of still-unexplored clusters in the galactic bulge or halo. The observations will provide key information on the early stages of our galaxy, when globular clusters formed.

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Hubble’s Star Clusters


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NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

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Details Last Updated Jul 03, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms

• Hubble Space Telescope
• Astrophysics
• Astrophysics Division
• Galaxies, Stars, & Black Holes
• Globular Clusters
• Goddard Space Flight Center
• Star Clusters
• Stars

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 Cosmic Adventure

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This week, a major contract, worth several million Euros, has been signed between ESO and a consortium of Chilean companies for the construction of telescope foundations for the Cherenkov Telescope Array Observatory’s (CTAO’s) southern hemisphere array (CTAO-South) at ESO’s Paranal Observatory in Chile. The contract includes more than 50 foundations for CTAO-South telescopes, as well as approximately 17 km of roads connecting these foundations to the support facilities. ESO, a founding member of the CTAO European Research Infrastructure Consortium and host of its southern array, signed the contract on behalf of this international organisation. The construction of this important civil infrastructure is expected to take one year, paving the way for the first telescopes to be erected on site. Therefore, this milestone marks the beginning of the array’s construction in the southern hemisphere. 

The CTAO will be the largest and most powerful ground-based observatory for gamma-ray astronomy. It is composed of two telescope arrays—CTAO-South, and CTAO-North in La Palma, Spain. One located in the southern hemisphere and the other in the northern hemisphere, both will keep a watchful eye out for an elusive form of radiation called Cherenkov radiation. When cosmic gamma rays reach the atmosphere and interact with it, they generate a cascade of ultra-energetic particles; as they move through the air, these particles create a faint blue flash of “Cherenkov light”. By analysing this faint light, astronomers can infer much about the cosmic sources, like supermassive black holes and supernova remnants, that emitted the original gamma rays. 

To capture Cherenkov radiation, the CTAO-South site will consist of 51 individual telescopes of different sizes to detect both bright and faint events. The site will cover an area of about 3 square kilometres and is located about 10 kilometres away from Cerro Paranal, the home of ESO’s Very Large Telescope. Once built, the CTAO will make data and analysis software publicly available for the entire global scientific community to share, strengthening worldwide collaboration and helping to answer questions across both astronomy and particle physics, like the hunt for dark matter, the mechanics of supernovae, and how dense neutron stars collide. 

The CTAO will be the first observatory of its kind, able to observe the high-energy Universe with unparalleled sensitivity. Its location near Cerro Paranal, far from light pollution sources and under one of the world’s darkest and most pristine night skies, is key to detecting the extremely faint Cherenkov blue light. 

More information 

In January 2025, the CTAO was established as a European Research Infrastructure Consortium (ERIC) by the European Commission. The Founding Members of the CTAO ERIC are Austria, the Czech Republic, the European Southern Observatory (ESO), France, Germany, Italy, Poland, Slovenia, and Spain. Additionally, Japan is a Strategic Partner, and the accession of Switzerland and Croatia as Founding Members is being processed.

arXiv:2503.01993v2 Announce Type: replace Abstract: The majority of core-collapse supernova (CCSN) progenitors are massive stars in multiple systems, and their evolution and final fate are affected by interactions with their companions. These interactions can explain the presence of circumstellar material in many CCSNe, and the inferred low mass in stripped-envelope supernova progenitors. Through binary interactions, stars can gain mass, lose mass, or merge, impacting their final properties. Specific sub-types of binary interaction products have been investigated but few detailed full population models exist. Using thousands of detailed simulations with updated prescriptions for binary interactions and winds at Milky Way and Magellanic Clouds metallicities, we follow the evolution of single massive stars, primaries in interacting binaries and coalescence products following common envelope evolution. We also follow the evolution of the surviving secondary star, with a compact companion formed from the evolutionary end of the primary star or alone if the system was disrupted in the first supernova. The endpoints of our simulations map the rich landscape of CCSN progenitors, and provide detailed mass-loss history and progenitor structures. We identify an important evolutionary phase for stripped-envelope supernova progenitors, in which the wind mass-loss rate of stars stripped by binary interaction rapidly increases in their final evolutionary stages, after core helium burning. These strong winds would give rise to a Wolf-Rayet (WR) spectral appearance, though only for a few millennia, in contrast to hundreds of millennia for their more massive WR counterparts. Such lightweight WR stars in binaries can account for observed properties of type Ib/c supernovae.

arXiv:2503.01993v2 Announce Type: replace Abstract: The majority of core-collapse supernova (CCSN) progenitors are massive stars in multiple systems, and their evolution and final fate are affected by interactions with their companions. These interactions can explain the presence of circumstellar material in many CCSNe, and the inferred low mass in stripped-envelope supernova progenitors. Through binary interactions, stars can gain mass, lose mass, or merge, impacting their final properties. Specific sub-types of binary interaction products have been investigated but few detailed full population models exist. Using thousands of detailed simulations with updated prescriptions for binary interactions and winds at Milky Way and Magellanic Clouds metallicities, we follow the evolution of single massive stars, primaries in interacting binaries and coalescence products following common envelope evolution. We also follow the evolution of the surviving secondary star, with a compact companion formed from the evolutionary end of the primary star or alone if the system was disrupted in the first supernova. The endpoints of our simulations map the rich landscape of CCSN progenitors, and provide detailed mass-loss history and progenitor structures. We identify an important evolutionary phase for stripped-envelope supernova progenitors, in which the wind mass-loss rate of stars stripped by binary interaction rapidly increases in their final evolutionary stages, after core helium burning. These strong winds would give rise to a Wolf-Rayet (WR) spectral appearance, though only for a few millennia, in contrast to hundreds of millennia for their more massive WR counterparts. Such lightweight WR stars in binaries can account for observed properties of type Ib/c supernovae.