Abstracts

The role of mass loss in constraining quenching time in dwarf galaxies from asymptotic-giant-branch and red-giant-branch star counts

P. Ventura. R. D’Souza, F. Dell’Agli, E. F. Bell, C. Gavetti, C. Fiumi, M. Tailo

The possibility of reconstructing the past star formation history of dwarf elliptical galaxies out of the Local Volume relies on modelling bright stellar populations currently evolving through the red-giant-branch (RGB) and asymptotic-giant-branch (AGB) phases. Recent studies proposed the use of the relative fractions of RGB and AGB stars populating specific boxes in the observational colour-magnitude plane to infer the epoch within which 90% of the stellar population of the galaxy formed (T90).

We aim to understand the physical processes of stellar evolution that are constrained by the relationship between the relative fraction of AGB and RGB stars of dwarf galaxies and the T90 epoch.

We used updated stellar models that include the description of dust formation in the wind to undertake a population synthesis approach that would allow us to monitor the variation of the NAGB/NRGB ratio with time. The effects of some specific ingredients, such as the mass loss experienced by low-mass stars during the RGB phase, and the details of the time variation of the star formation rate, were extensively explored and tested against data in this study.

The mass lost by low-mass stars during the RGB evolution proves the most relevant ingredients affecting the time variation of NAGB/NRGB: at metallicities 1/10 solar, a mass loss of 0.25 solar masses is required to reproduce the observations. This analysis allowed us to derive a relationship between NAGB/NRGB and T90, with a 1 Gyr uncertainty on T90

Reference : Astronomy and Astrophysics, 2026, 709, A219
URL : https://www.aanda.org/articles/aa/full_html/2026/05/aa59206-26/aa59206-26.html

Milky Way’s warped disc traced by AGB stars

Tanya Kushwahaa (Cardiff), Mikako Matsuura (Cardiff), Jason A. S. Hunt (Surrey), Daisuke Kawata (MSSL/UCL), Roger Wesson (Cardiff, UCL, Maynooth), Timothy A. Davis (Cardiff)

While the presence of the Galactic warp has long been established from observations of HI, gas, the Gaia measurements of over 1 billion stars with parallaxes have enabled much more detailed studies using stellar populations. Here, we demonstrate that asymptotic giant branch (AGB) stars, an evolved phase of low- and intermediate-mass stars, can serve as an effective tracer of the Galactic warp. We use two distinct AGB populations: C-rich AGB stars, representing stars of about 1 Gyr in age with main-sequence masses of 2-2.5 Msun, and intermediate-mass (3-5 Msun) O-rich AGB stars, corresponding to ages of 100-300 Myr. The downward warp traced by O-rich AGB stars is consistent with that found from Cepheids, which is expected given their similar ages. The more numerous C-rich AGB stars clearly reveal the Galactic warp over a wide range of azimuthal angles. Their warp appears to reach larger amplitudes than that of Cepheids across azimuthal angles. Our results show that C-rich AGB stars, together with intermediate-mass O-rich AGB stars, provide new constraints on the Galactic warp at intermediate stellar ages, offering a new insight into the stellar age and warp amplitude relation.

Reference : accepted in MNRAS letter
URL : https://doi.org/10.48550/arXiv.2606.10235

Calcium-bearing cyanopolyynes in IRC+10216

Millar T J

ABSTRACT
In recent years, a number of metal-containing, carbon-chain species have been detected in the external circumstellar envelope of the carbon-rich asymptotic giant branch star IRC+10216. The most common metal detected in such species is Mg, for which molecules as large as MgC$_5$N, MgC$_5$N$^+$, MgC$_6$H, and MgC$_6$H$^+$ have been observed. In this paper, we calculate the likely abundances of the Ca-bearing cyanopolyynes, CaC$_2n+1$N for n = 1–4, drawing the conclusion that the observed abundance of CaNC must be made from much larger Ca-terminated cyanopolyyne ions, which requires considerable rearrangement in their dissociative recombination. We pay particular attention to the detectability of CaC$_3$N whose rotational spectrum has recently been measured.

Reference : 2026 Monthly Notices of the Royal Astronomical Society, 549,
URL : https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1002/8698252

Discovery of a nebula associated with a high proper motion sdB star

R. Ortiz, F. Bijarchian, M.A. Guerrero, M. Akhlaghi and M. Serra-Ricart

All B-type subdwarf stars (hereafter sdB) should have low flux of ionizing photons, making them incapable of producing a noticeable circumstellar photoionized shell. However, a few sdB stars have been associated with circumstellar nebulae, resembling in some cases a planetary nebula. These discoveries spark doubts about the nature of the physical processes behind the formation of the nebula. In this paper, we describe the newfound parabolic-shaped nebula associated with the high proper motion sdB star TYC 3315-1807-1. The apex of the Halpha nebula is situated approximately 0.5 arcmin in the direction of the stellar proper motion. A wider parabolic-shaped nebula is also detected in WISE W1 infrared images at 3.4 micron, whereas GALEX images show extended far-UV emission around the star within the optical and mid-IR emissions. Like most other sdB stars with associated nebulae, TYC 3315-1807-1 moves at a high-speed (102 km/s) across the Galactic plane. The low luminosity of TYC 3315-1807-1 cannot provide its wind with the momentum necessary to form and keep a bow shock. The nebula around TYC 3315-1807-1 is rather suggested to be a Mach wave partially excited by shocks and photoionization or the encounter of the star with an over-density clump in the ISM.

Reference : accepted in MNRAS
URL : https://arxiv.org/abs/2606.24398

The first hours and days of the 2021 explosion of the recurrent symbiotic nova RS Ophiuchii

Skopal, Augustin, Vrašťák, Martin, Teyssier, Francois, Fujii, Mitsugu, Shugarov, Sergei, Šlechta, Miroslav, Wolf, Marek

The accretion of matter on a massive white dwarf (WD) can lead to repeated nuclear explosions on its surface over a timescale of years to decades. The seventh explosion of the recurrent symbiotic nova RS Ophiuchi (RS Oph) was recorded on August 8, 2021. In this paper, we examine its early evolution, from 9 hours before its optical maximum until day 42. We achieved our goal by modeling the spectral energy distribution (SED) using optical spectroscopy and simultaneous BVRcIc photometry, supplemented by JHKL photometry and ultraviolet spectroscopy from previous explosions in 2006 and 1985. Our SED models revealed an early stage of development of the ejecta bipolar structure, consisting of a flared, density-enhanced equatorial disk and low-density regions in bipolar directions. The comparability of the internal shocks’ luminosity in the equatorial outflow, inferred from our model parameters, with the luminosity of the warm WD pseudophotosphere during its presence in the spectrum (until day 42) confirmed that a significant part of its radiation originates from reprocessed shock emission. We explain the formation and evolution of the bipolar ejecta structure during RS Oph explosions by the rotation of the accreting WD. Such an ejecta structure provides a natural framework for the generation of strong internal shocks and thus γ-ray emission inside the ejecta.

Reference : 35 pages, 13 figures, 9 tables, 6 Appendices, accepted for ApJ
URL : https://arxiv.org/abs/2606.13202

Constraints for nuclear astrophysics from an unusual presolar silicate-oxide aggregate grain found in primitive ordinary chondrite Meteorite Hills 00526

Nittler Larry R., Barosch Jens, Alexander Conel M. O’D., Wang Jianhua

We report O, Mg–Al, Si, Ca, and Ti isotopic data for an unusual presolar oxide/silicate aggregate grain, M526-69, previously reported in the primitive ordinary chondrite Meteorite Hills 00526. The ≈1 μm aggregate consists of a Mg- and Ca-rich silicate, an Al-rich oxide, and a tiny TiO2 grain. A large 18O depletion and high inferred 26Al/27Al classifies M526-69 as a Group 2 grain. Both low-mass (LM) and intermediate-mass (IM) asymptotic giant branch (AGB) stars are considered viable candidate parent stars of Group 2 grains based on their O isotopes and inferred 26Al/27Al ratios. The lack of a large 30Si excess in M526-69 strongly supports an LM-AGB origin for it and other Group 2 grains. The stable Mg, Ca, and Ti isotopes all reflect the initial composition of the parent star, set by galactic chemical evolution (GCE) processes. Presolar O-rich grains provide a better measure of the GCE trends for Ti isotopes than presolar SiC grains as the latter are also affected by neutron capture reactions in the parent stars. Most of the Mg, Ca, and Ti isotopic ratios in M526-69 are consistent with its parent star having metallicity lower than solar. However, small excesses in stable non-radiogenic 26Mg, 46Ti, and 44Ca do not fit this pattern and instead point to heterogeneous GCE processes, though quantitative modeling is needed to test this hypothesis. Multi-phase presolar grains are extremely valuable for nuclear astrophysics as they can both provide isotopic compositions for multiple elements that must be matched at a single time and place in a single star.

Reference : 2026 The European Physical Journal A, 62,
URL : https://arxiv.org/abs/2605.02055

Stellar Evolution Along the Asymptotic Giant Branch as Revealed by the Shape of Miras’ Visual Light Curves

Do Thi Hoai, Pham Tuyet Nhung, Pierre Darriulat, and Mai Nhat Tan

A new analysis of a sample of visual light curves of Mira variables is presented. The curves cover the past four decades and are selected from the AAVSO database as including a large number of high-density observations. The aim is to offer a more quantitative and more systematic picture than available from earlier studies. The results corroborate earlier descriptions and reveal new correlations between the shapes of the light curves and the evolution of the star along the asymptotic giant branch (AGB). A family of nearly sinusoidal curves associated with M spectral types and displaying no sign of having experienced third-dredge-up events is identified with confidence. A detailed study of its properties is presented and used to suggest possible interpretations. All other curves are distinct from this family and start departing from it by displaying a broader luminosity minimum, progressively taking the form of a hump climbing the ascending branch. Possible relations between such progression and the evolution of the star along the AGB are discussed. New correlations between parameters defining the shape of the light curve and the state of the star are revealed; while the average trend is established with confidence, deviations from it cause a significant scatter of the parameters of the curves. Comments aimed at shedding light on the underlying physics are resented together with speculative interpretations, in the hope that they could encourage and inspire new studies, in particular based on models of the inner star dynamics.

Reference : 2025, ApJ, 982, 201
URL : https://iopscience.iop.org/article/10.3847/1538-4357/adb8d9/pdf

From the light curves of long period variables to their evolution along the Asymptotic Giant Branch

P.T. Nhung, M.N. Tan, D.T. Hoai and P. Darriulat

A sample of 116 long period variables is studied with the aim to reveal relations between the properties of their light curves and of their evolution along the asymptotic giant branch (AGB). Each light curve is carefully scrutinized, and its properties are summarized in a set of five parameters. One of these, which measures the relative width of the light maxima and minima, is found to be particularly efficient at revealing significant correlations with the current state of the star on the AGB. The picture that had been sketched in an earlier work is clarified, and new features are revealed. In particular, the evolution on the AGB of stars having not yet experienced a third-dredge-up event is shown to go together with a closely related path followed by the light curve in the parameter space. Moreover, evidence is found for the existence of two different types of light curves for stars having experienced dredge-up events strong enough for their impact to be detectable. For some, probably associated with higher initial mass stars, the light maximum becomes broader as the star evolves along the AGB, while for others it becomes narrower. Interpretations are proposed, however, often too speculative to be firmly ascertained: the results presented raise several unanswered questions and point to the need for new observations and analyses, suggesting that light curves still carry more messages and information than have been currently possible to decrypt.

Reference : 2025, ApJ, 994, 130
URL : https://iopscience.iop.org/article/10.3847/1538-4357/ae0a31/pdf

Recalibration of the H α Surface Brightness–Radius Relation for Planetary Nebulae Using Gaia DR3: New Distances and the Milky Way Oxygen Radial Gradient

Cavichia Oscar, Monteiro Hektor, Cerviño Miguel, da Cunha-Silva Adalberto R., Maciel Walter J., Cardoso André F. S.

The spatial distribution of chemical elements in the Galactic disk provides key constraints on models of galaxy evolution. However, studies using planetary nebulae (PNe) as tracers have been historically limited by large uncertainties in their distances. To overcome the long-standing distance uncertainties, we recalibrated the H α surface brightness–radius relation from Frew et al. with Gaia DR3 parallaxes, deriving distances for 1130 PNe of which 415 have Bayesian distances based on Gaia DR3 parallaxes. The O/H radial gradient for 231 disk PNe is fitted considering three models: a single linear gradient and segmented linear fits with one or two breaks. The segmented fits indicate a change in slope near the solar radius ( R ∼ 8 kpc), with a flatter or slightly positive gradient inward and a steeper negative gradient outward. This feature may reflect changes in star formation efficiency driven by the Galactic bar or the corotation resonance of the spiral arms. The breaks in the metallicity radial gradients observed in this work may result from the superposition of distinct stellar populations associated with the thin and thick disks. The two-dimensional O/H distribution in the Galactic plane supports the adopted distances and reveals modest azimuthal asymmetry, with enhanced abundances near the bar at positive longitudes, and a bimodal abundance structure between the inner and outer solar regions. Our results provide new constraints on the chemical evolution of the Milky Way, the impact of nonaxisymmetric structures, and the possible existence of distinct radial abundance regimes across the Galactic disk.

Reference : 2026 The Astrophysical Journal, 1004, 220
URL : https://iopscience.iop.org/article/10.3847/1538-4357/ae7334

Another one bites the dust - how red supergiants keep surprising us

Jacco Th. van Loon

Extreme red supergiant WOH G64 has led researchers a merry dance these last few years, but what does it reveal about the secret lives of these beasts? This article sets the latest observations of WOH G64 in the context of what has been observed in other supergiants such as Betelgeuse and what we are learning from the massive stars that have been identified to explode as a supernova.

Reference : Astronomy & Geophysics, 2026, volume 67, 2.18-2.21
URL : https://arxiv.org/abs/2606.28428

Annoucements

The Lifecycle of Massive Stars

e-Book and Special Issue of the open access MDPI journal Universe
"The Lifecycle of Massive Stars"

We invite you to submit original work pertaining to any aspect of the physics of massive stars and their effect on the environment.

You’d be joining an exquisite group of scientists who have agreed to write reviews - Emma Beasor, Julia Bodensteiner, Vikram Dwarkadas, Roberta Humphreys, Ralf Klessen, Eva Laplace, Anna McLeod, Raman Prinja, Sophie Rosu, Raffaella Schneider.

We encourage authors from under-represented communities to contribute and are keen to offer them our support.

Best wishes,
Jacco van Loon, Guest Editor
Keele University, UK
email: j.t.van.loon@keele.ac.uk

Submission deadline: 1 August 2026 (contact me to negotiate an extension)

https://www.mdpi.com/journal/universe/special_issues/D464CGUHD0

1st announcement: ALMA at 15 years conference open for abstract submissions

1st announcement: ALMA at 15 years conference

Rationale
We are pleased to announce that the international conference "ALMA at 15 Years: Science, Synergies, and the Road Ahead" will be held in person from Feb. 22–26, 2027, at Academia Sinica’s Nangang campus in Taipei, Taiwan. The conference will highlight ALMA’s latest results, especially since the last Pan-ALMA conference held in 2023 and identify exciting directions for future ALMA research.

The program will feature invited and contributed science presentations, along with updates on the Wideband Sensitivity Upgrade (WSU), tutorial sessions on the archival and CARTA systems, and discussions of future ALMA prospects. Talks and posters presenting scientific work using ALMA and/or its synergies with other facilities across all areas of astronomy are welcome. Please visit the official conference website: https://2027alma.org

Important Dates
Abstract Submission Opens: June 15, 2026
Abstract Submission Deadline: September 15, 2026
Early-Bird Online-registration Opens: September 30, 2026
Notification of Abstract Acceptance: Late Oct./Early Nov., 2026
Early Bird Online-registration Deadline: November 27, 2026
Online Registration Deadline: January 20, 2027

SOC
John Carpenter (JAO, Chile), Paola Caselli (MPE, Germany), Marilyn Cruces (UC Chile, Chile), Leen Decin (KU Leuven, Belgium), Maria Diaz Trigo (ESO, Germany), Bunyo Hatsukade (NAOJ, Japan), Rodrigo Herrera-Camus (Universidad de Concepción, Chile), Jongsoo Kim (KASI, Korea), Lihwai Lin (ASIAA, Taiwan; Chair), Leslie Looney (UIUC, USA), Brett McGuire (MIT, USA), Jennifer Donovan Meyer (NRAO/NAASC, USA)

LOC
Cindy Chiu (ASIAA), Tien-Hao Hsieh (TARA), Sheng-Jun Lin (ASIAA), Yu-Nung Su (ASIAA), Ya-Wen Tang (ASIAA), Wei-Hao Wang (ASIAA; Chair)

Contact
Should you have any further inquiries, please feel free to contact the ALMA 2027 Abstract Submission & Registration Office (email: reg@2027alma.org)

We look forward to seeing you in Taipei!

Best regards,
Lihwai Lin (on behalf of SOC)

Two Postdoctoral Positions in Unveiling the Interaction Physics of Giant Binary Stars (ERC Advanced Grant SOPHIA)

We are seeking two highly motivated postdoctoral researchers to join the ERC Advanced Grant project SOPHIA, led by Prof. Leen Decin at the Institute of Astronomy of KU Leuven.

SOPHIA aims to transform our understanding of how stars evolve by moving beyond simplified models and accounting for key physical processes such as mass loss, stellar winds, and binary interactions. The project combines cutting-edge observations, advanced modelling, and large datasets, including the upcoming Gaia Data Release 4.

We are recruiting two postdoctoral researchers, each focusing on a complementary aspect of the project:
– Position A: Stellar Winds, Mass Loss, and Radiative Transfer Modelling
– Position B: Binary Star Evolution with Gaia

More information and application instructions on https://fys.kuleuven.be/ster/vacancies/vacancies#PD_SOPHIA