The first meeting of our new international team on thermonuclear bursts has just concluded. Team members and local attendees met in Beijing at the International Space Science Institute's Chinese networking venue, at NSSC. Attendees from the Netherlands, USA, Spain, Japan, China and of course Australia delivered talks and participated in discussions ranging widely over topics relevant to thermonuclear bursts, and we also heard about exciting new observations from new facilities like Insight-HXMT and Einstein Probe.

As is tradition we broke up the scientific sessions with excursions to local sights including the Forbidden City and a nearby stretch of the Great Wall. We enjoyed wonderful late autumn weather and the generous hospitality of team leader Zhaosheng Li and students from Xiangtan U..

Labels: 2025, visits

One of the most successful efforts to date with our GOTO telescope network is the followup and detection of gamma-ray burst afterglows. Our wide field of view is well suited to covering the relatively large Fermi localisation regions, and collaboration member Amit Kumar assembled a comprehensive report on our localization and multiband follow-up of seven Fermi/GBM and MAXI/GSC triggered long GRBs: (240122A, 240225B, 240619A, 240910A, 240916A, 241002B, and 241228B) discovered by GOTO in 2024. Observations and followup include optical spectroscopy, radio and X-ray detections to fully characterise these events. Although their optical afterglows resemble those of typical long GRBs, the prompt spectra are consistently harder than the long-GRB average. Monash PhD student Sergey Belkin contributed broad-band afterglow modelling, to constrain jet half-opening angles to a few degrees, and estimate beaming-corrected kinetic energies. Amit's paper has now been published by MNRAS.

Labels: 2025, outreach

Our GOTO collaboration held it's latest scientific meeting in hybrid format over the last two days. We heard from the leads of our various working groups on the progress chasing supernovae, gamma-ray bursts, and even more mysterious transients. I attended remotely from Spain, during a break in a 3-week cycling holiday crossing the Iberian Peninsula.

A highlight for me was the presentations by Monash PhD student Sergey Belkin, working on followups of gamma-ray bursts detected with the Fermi satellite, and Masters candidate Kangming Pu, working on a new project aimed at systematic followup of asteroids observed with GOTO. While Sergey has already had a number of successes with discoveries and detections of GRB afterglows, the asteroid work is of particular interest, as it's a relatively unexplored area for GOTO but potentially could have some exciting new science outcomes. Amongst other objects that Kangming has detected in our GOTO network observations is the remarkable interstellar comet, 3I/ATLAS. Hopefully much more interesting science to come!

Labels: 2025, meetings

Our GOTO telescope network has already discovered many new objects, but GOTO 065054+593624 was a bit special; this 8.5-mag nova outburst was discovered in real-time, first by our Kilonova Seekers volunteers. Team members Tom Killestein and Lisa Kelsey report the discovery in their paper, now accepted by Astronomy & Astrophysics.

As reported in the paper, the followup observations provided extensive coverage of the "superoutburst", which exhibited typically complex behaviour for such objects; an initially declining bright phase lasting approx. 3 weeks, followed by 10(!) successive "re-flares" each lasting just a few days. Remarkably, this object may have been detected in outburst last in 1951, 73 years ago!

Accompanying the paper were press releases from Warwick, Monash (the latter also acknowledging the contribution of Monash PhD student Sergey Belkin), Portsmouth, and our other partners, and the story was picked up by BBC News, The Independent, Agenzia ANSA (Italian), Bloomberg (Bulgarian), Your Local Guardian and The Irish News.

Labels: 2025, outreach

This week I attended the second Vasto Accretion Meeting, held in lovely Vasto, Italy. Building on the success of the 2023 meeting, this year's instalment was expanded to two weeks duration, with the first week focussing on binaries. The program covered a wide range of topics and objects, across all wavelengths. A good mix IMO of review talks and new results, with a strong showing from junior researchers and students.

I gave an invited talk on thermonuclear bursts, which was followed (in the same session) by terrific presentations by Yuri Cavecchi and Amy Knight. Great discussions followed in the coffee sessions, held in the beautiful gardens of the lovely Palazzo d'Avalos, with wonderful views down to the marina and across the Adriatic.

Kudos to the organisers, particularly Simone Scaringi for not only repeating their 2023 success but raising the bar for 2025! Looking forward to future instalments of this great meeting!

Labels: 2025, meetings

Yuri Cavecchi has done more than anyone IMO to understand the broad properties of thermonuclear bursts. In his latest paper (arXiv:2506.11966) he describes further refinement of his phenomenological model that explains the relative inefficiency of unstable thermonuclear burning at high accretion rates.

The model has several requirements, including a varying distribution of accretion over the neutron star; stable burning (at the equator) coexisting with unstable (at higher latitudes); and significant "pollution" of the burst fuel by ashes dredged up into the fuel layer, possibly by convection. This pollution contribution is now on a firmer basis with support from MESA simulations, and as a whole the model matches the burst observations and potentially allows us to deduce changes in the accretion disk geometry close to the star. The paper is under review by ApJL.

Labels: 2025, papers