From haakon.andresen at astro.su.se Mon Jan 19 09:34:01 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Mon, 19 Jan 2026 08:34:01 +0000 Subject: [Okc-wp4] First EO talk of 2026 Message-ID: Dear Everyone, I hope you all had a nice break and a great start to the new year. The year is about to get even better, since this week marks the official start of the 2026 Extreme Objects season. First, let me remind you that Kosta's licentiate on 20th of January at 10:00 in room FB55. He will discuss a few very interesting supernovae. His opponent Christa Gall will talk about the complex nature of dust in supernovae on Thursday at 13:15 in A5:1003 (https://stockholmuniversity.zoom.us/j/3575421837) Christa Gall Why dust is not a parameter Abstract: Astrophysical transients, such as massive stars exploding as supernovae (SNe) are the spotlights of the universe, which is filled with tiny solid particles, cosmic dust. Such dust absorbs and deflects this light and distorts our view of the visible universe. However, the mechanism of dust formation in SNe and reprocessing in the interstellar medium is complex, likely producing regions in galaxies with different dust properties. I will discuss current 'dusty' challenges and what we have learned from recent observations of dust in SNe and galaxies at various points in cosmic time and how these may impact deriving precise distances from Type Ia supernovae Best, Haakon (on behalf of the organisers) -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Jan 22 12:08:38 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 22 Jan 2026 11:08:38 +0000 Subject: [Okc-wp4] First EO talk of 2026 In-Reply-To: References: Message-ID: <67e73c10207549bb87e0691dd95dba26@astro.su.se> Reminder ________________________________ From: Okc-wp4-at-fysik.su.se on behalf of Haakon Andresen via Okc-wp4-at-fysik.su.se Sent: 19 January 2026 09:34:01 To: EO meeting email Subject: [Okc-wp4] First EO talk of 2026 Dear Everyone, I hope you all had a nice break and a great start to the new year. The year is about to get even better, since this week marks the official start of the 2026 Extreme Objects season. First, let me remind you that Kosta's licentiate on 20th of January at 10:00 in room FB55. He will discuss a few very interesting supernovae. His opponent Christa Gall will talk about the complex nature of dust in supernovae on Thursday at 13:15 in A5:1003 (https://stockholmuniversity.zoom.us/j/3575421837) Christa Gall Why dust is not a parameter Abstract: Astrophysical transients, such as massive stars exploding as supernovae (SNe) are the spotlights of the universe, which is filled with tiny solid particles, cosmic dust. Such dust absorbs and deflects this light and distorts our view of the visible universe. However, the mechanism of dust formation in SNe and reprocessing in the interstellar medium is complex, likely producing regions in galaxies with different dust properties. I will discuss current 'dusty' challenges and what we have learned from recent observations of dust in SNe and galaxies at various points in cosmic time and how these may impact deriving precise distances from Type Ia supernovae Best, Haakon (on behalf of the organisers) -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Mon Feb 2 08:06:11 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Mon, 2 Feb 2026 07:06:11 +0000 Subject: [Okc-wp4] EO seminar Thursday 5th Message-ID: <36f24bf9d08540c4a9719dd6d8d64830@astro.su.se> Dear Everyone, These week's seminar will be given by Priscilla, we meet on Thursday in A5:1003 at 13:15. Today, at 10:00 in room FB52, EOer Anamaria will defend her PhD thesis. Best, Haakon (on behalf of the organiseres) Speaker: Priscila Pessi Title: They Look Like Type II Supernovae — But They Are Not Abstract: Massive stars that retain their hydrogen envelopes until the end of their lives can produce hydrogen-rich Type II supernova explosions. However, not all transients that resemble Type II supernovae arise from the same physical processes. Some energetic events can mimic Type II supernovae without being genuine stellar explosions, while others may appear hydrogen-rich based on early classifications but lack hydrogen in their spectra. In this talk, I will present two illustrative cases. The first is a transient initially classified as a core-collapse supernova that, based on detailed observational analysis, was later identified as nuclear activity in its host galaxy. The second is an ongoing study of a supernova candidate originally classified as Type II, for which no hydrogen features are detected in the spectra. Together, these examples show how misclassification can lead to incorrect inferences about the physical mechanisms powering different transients, and they highlight the limitations of current supernova diagnostics. This work emphasizes the need for robust identification strategies to correctly interpret the physics of transients in the era of large survey data sets. -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Feb 5 11:03:48 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 5 Feb 2026 10:03:48 +0000 Subject: [Okc-wp4] Reminder: EO seminar today Message-ID: <8d6021a1b635445980e643f04913002c@astro.su.se> Reminder of today's meeting in A5:1003 at 13:15 Speaker: Priscila Pessi Title: They Look Like Type II Supernovae — But They Are Not Abstract: Massive stars that retain their hydrogen envelopes until the end of their lives can produce hydrogen-rich Type II supernova explosions. However, not all transients that resemble Type II supernovae arise from the same physical processes. Some energetic events can mimic Type II supernovae without being genuine stellar explosions, while others may appear hydrogen-rich based on early classifications but lack hydrogen in their spectra. In this talk, I will present two illustrative cases. The first is a transient initially classified as a core-collapse supernova that, based on detailed observational analysis, was later identified as nuclear activity in its host galaxy. The second is an ongoing study of a supernova candidate originally classified as Type II, for which no hydrogen features are detected in the spectra. Together, these examples show how misclassification can lead to incorrect inferences about the physical mechanisms powering different transients, and they highlight the limitations of current supernova diagnostics. This work emphasizes the need for robust identification strategies to correctly interpret the physics of transients in the era of large survey data sets. -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Mon Feb 16 13:06:03 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Mon, 16 Feb 2026 12:06:03 +0000 Subject: [Okc-wp4] Seminar on February 19th Message-ID: <21ad230525b14bf3a1905be1ba5d77a6@astro.su.se> Dear Everyone, The next EO seminar will take place this Thursday. When: 13:15 19th of February Where: A5:1003 Speaker: Julia Alhvind Title: X-Ray Observations of Old Nearby Supernovae and Constraints on Compact Objects Population Abstract: The properties of compact objects formed in core-collapse supernovae (SNe) remain uncertain. X-ray observations years to decades after explosion provide a way to probe these young remnants, as hard emission from the central regions can emerge once the ejecta becomes sufficiently transparent. In this talk, I will present a systematic study of late-time X-ray emission from 242 nearby core-collapse SNe based on more than 600 archival observations. I will show new X-ray SN detections, highlight one case with a possible hard central component, and demonstrate how upper limits from the full sample can be used to constrain the young pulsar population. Best, Haakon (on behalf of the organisers) -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Feb 19 12:18:16 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 19 Feb 2026 11:18:16 +0000 Subject: [Okc-wp4] Seminar on February 19th In-Reply-To: <21ad230525b14bf3a1905be1ba5d77a6@astro.su.se> References: <21ad230525b14bf3a1905be1ba5d77a6@astro.su.se> Message-ID: <96806d5f9c784edaaeb2a5b953a5faf1@astro.su.se> Reminder. ________________________________ From: Okc-wp4-at-fysik.su.se on behalf of Haakon Andresen via Okc-wp4-at-fysik.su.se Sent: 16 February 2026 13:06:03 To: EO meeting email Subject: [Okc-wp4] Seminar on February 19th Dear Everyone, The next EO seminar will take place this Thursday. When: 13:15 19th of February Where: A5:1003 Speaker: Julia Alhvind Title: X-Ray Observations of Old Nearby Supernovae and Constraints on Compact Objects Population Abstract: The properties of compact objects formed in core-collapse supernovae (SNe) remain uncertain. X-ray observations years to decades after explosion provide a way to probe these young remnants, as hard emission from the central regions can emerge once the ejecta becomes sufficiently transparent. In this talk, I will present a systematic study of late-time X-ray emission from 242 nearby core-collapse SNe based on more than 600 archival observations. I will show new X-ray SN detections, highlight one case with a possible hard central component, and demonstrate how upper limits from the full sample can be used to constrain the young pulsar population. Best, Haakon (on behalf of the organisers) -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Feb 26 14:43:52 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 26 Feb 2026 13:43:52 +0000 Subject: [Okc-wp4] Next meeting, March 5th Message-ID: Dear Everyone, The next EO meeting will take place next week on Thursday March 5th. When: 13:15 5th of March Where: A5:1003 Speaker: Matteo Bugli Title: The impact of magnetic field topology and nuclear equations of state on magneto-rotational supernovae Best, Haakon (on behalf of the organisers) -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Mar 5 11:58:21 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 5 Mar 2026 10:58:21 +0000 Subject: [Okc-wp4] Reminder: EO seminar at 13:15 in A5:1003. The impact of magnetic field topology and nuclear equations of state on magneto-rotational supernovae Message-ID: <7170cd76d98b4a2d833f27a3872a8b1b@astro.su.se> Dear Everyone, Hope to see all of you after lunch today for the seminar, at 13:15. Speaker: Matteo Bugli Title: The impact of magnetic field topology and nuclear equations of state on magneto-rotational supernovae -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Mar 12 16:27:38 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 12 Mar 2026 15:27:38 +0000 Subject: [Okc-wp4] EO seminar on the 19th Message-ID: <3794e684e0164acbb347f3e01dfccd81@astro.su.se> Dear Everyone, Next week's seminar will be given by Liubov Kovalenko. Thursday the 19th at 13:15 in A5:1003. Zoom: https://stockholmuniversity.zoom.us/j/3575421837 Best, Haakon (on behalf of the organisers) Speaker: Liubov Kovalenko Title: Rotation and Magnetic Fields in Extreme Core-Collapse Supernovae Abstract: Core-collapse supernovae are shaped by the interplay of gravity, neutrinos, rotation, and magnetic fields in the first seconds after collapse. While most simulations focus on neutrino-driven hydrodynamics, magnetic fields are likely essential for understanding the most rapidly rotating and extreme explosions, as well as their connection to magnetar formation. In this talk, I will present 3D simulations of an extremely compact 39-solar-mass progenitor and compare three models: a non-rotating baseline case, a rotating case without magnetic fields, and a rotating magnetized case. Although the collapse and bounce are broadly similar, the post-bounce evolution differs significantly. Rotation and magnetic fields alter the shock evolution, outflow morphology, proto-neutron-star dynamics, and the angular structure of the neutrino emission. These differences are especially important for multimessenger signals. Because the newly formed core is initially opaque to photons (and even neutrinos), gravitational waves may provide the earliest direct observational window into the proto-neutron star just after bounce. Using these models, I will discuss how rotation and magnetic fields influence both the explosion dynamics and the gravitational-wave signatures that may provide access to the innermost post-bounce evolution. -------------- next part -------------- An HTML attachment was scrubbed... URL: From haakon.andresen at astro.su.se Thu Mar 19 09:24:16 2026 From: haakon.andresen at astro.su.se (Haakon Andresen) Date: Thu, 19 Mar 2026 08:24:16 +0000 Subject: [Okc-wp4] Reminder: EO seminar today at 13:15 Message-ID: Quick reminder of the seminar: At 13:15 in A5:1003. Zoom: https://stockholmuniversity.zoom.us/j/3575421837 Speaker: Liubov Kovalenko Title: Rotation and Magnetic Fields in Extreme Core-Collapse Supernovae Abstract: Core-collapse supernovae are shaped by the interplay of gravity, neutrinos, rotation, and magnetic fields in the first seconds after collapse. While most simulations focus on neutrino-driven hydrodynamics, magnetic fields are likely essential for understanding the most rapidly rotating and extreme explosions, as well as their connection to magnetar formation. In this talk, I will present 3D simulations of an extremely compact 39-solar-mass progenitor and compare three models: a non-rotating baseline case, a rotating case without magnetic fields, and a rotating magnetized case. Although the collapse and bounce are broadly similar, the post-bounce evolution differs significantly. Rotation and magnetic fields alter the shock evolution, outflow morphology, proto-neutron-star dynamics, and the angular structure of the neutrino emission. These differences are especially important for multimessenger signals. Because the newly formed core is initially opaque to photons (and even neutrinos), gravitational waves may provide the earliest direct observational window into the proto-neutron star just after bounce. Using these models, I will discuss how rotation and magnetic fields influence both the explosion dynamics and the gravitational-wave signatures that may provide access to the innermost post-bounce evolution. -------------- next part -------------- An HTML attachment was scrubbed... URL: