[Astronomy seminar] Astro Department Seminar - Fri Jan 20th 10:30 - Smaranika Banerjee

[Astronomy seminar announcements]

Dear all,

The next SU astronomy departmental seminar will take place on Friday March 24th at 10:30 in room FC 61 (AlbaNova building, 6th floor) and on zoom.

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Speaker: Priscila Pessi (SU)
Title: Connecting observed properties of supernovae to progenitor scenarios
https://www.albanova.se/event/astronomy-departmental-seminar-priscila-pessi-su/ <https://www.albanova.se/event/astronomy-departmental-seminar-priscila-pessi-su/>

Abstract:
Supernovae (SNe) mark the explosive death of certain groups of stars. Theoretical models that take into account stellar evolution of predefined progenitor stars propose different explosion mechanisms. However, it is still not clear how the variation of characteristics such as metallicity, mass loss rate and multiplicity – among others – impact on the observed properties of SNe. Even when some models have been supported by observations, the scarcity of direct detections of progenitor stars prevents us from understanding the exact nature of the stars that explode as different types of SNe. 
 
In this talk I will present the observational analysis of three different SNe samples done during my PhD. The goal of the analysis is to associate observed characteristics to progenitor properties. The first studied sample consists of the light curves of 73 type II SNe from the Carnegie Supernova Project (CSP) and 21 type IIb SNe from the literature. To compare the light curves in a consistent manner I parameterized them in terms of their time derivatives. My work is the first one implementing such analysis. We found distinct properties for the SNe II and IIb light curves. This leads to the conclusion that they most likely arise from different types of progenitors. 
For the second sample analysis, I used the novel technique of light curve time derivatives to study 54 rapid-cadence SNe Ia light curves from the CSP. Although the light curves of SNe Ia are homogeneous enough to be standardized and used as distance indicators, they present a subtle feature or “kink” soon after the i-band light curve peak that has been previously ignored. Analyzing the time derivatives, we were able to characterize the phase and strength of the kink. We could not directly link this feature to any other observed characteristic but we found that considering only the SNe with the  strongest kinks substantially reduces the Hubble residuals. 
The third sample consists of the light curves and spectral series of  six luminous SNe followed up by the Public European Southern Observatory Spectroscopic Survey of Transient Objects. The optical light curves of this sample are more luminous, exhibit bluer colors  and decline faster than other SNe type II. The spectral series are blue at early times, they show weak or nonexistent metal lines, and broad and boxy Hα emission profiles with no associated absorption component. The shared characteristics support a similar powering scenario for all of them. We propose interaction with CSM that is not dense enough to be optically thick to electron scattering on large scales, which is consistent with the lack of narrow emission lines in the spectra. I will finish the talk by presenting the project I am currently working on, that involves the study of a large sample of SLSNe II. 

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We look forward to seeing many of you there. Thanks!

Eliot and Kris



Upcoming Events:

2023-03-31	Mattia Sirressi (SU)
2023-04-07	No seminar (Långfredagen)
2023-04-14	Charlotte Mason (DAWN, NBI U. Copenhagen)

The calendar for later planned seminars is available here <https://ebox.su.se/owa/calendar/75d76b284ca84db1a85c4e021d1133e8@astro.su.se/22bc11d486d04afaa009a9730dd065d65524176602456481514/calendar.html>.
(Please note that calendar can be subject to updates)



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Topic: Astronomy Department Seminar
Time: March 24th, 2023 10:30 AM Stockholm

Join Zoom Meeting:
https://stockholmuniversity.zoom.us/s/61002076352 <https://stockholmuniversity.zoom.us/s/61002076352>
Meeting ID: 610 0207 6352




> On 17 Jan 2023, at 09:58, Eliot Ayache <eliot.ayache at astro.su.se> wrote:
> 
> Dear all,
> 
> The next SU astronomy departmental seminar will take place on Friday January 20th at 10:30 in room FC 61 (AlbaNova building, 6th floor) and on zoom.
> 
> ———————————
> Speaker: Smaranika Banerjee
> Title: Early kilonova from neutron star merger
> https://www.albanova.se/event/early-kilonova-from-neutron-star-merger/ <https://www.albanova.se/event/early-kilonova-from-neutron-star-merger/>
> 
> Abstract:
> In binary neutron star (BNS) mergers, the radioactive decay of freshly synthesized heavy elements produces emissions in the ultraviolet-optical-infrared range, giving rise to a transient called a kilonova. The kilonova is an excellent probe to understand the origin of elements heavier than iron. The observational properties of the kilonova (light curve and spectra) depend on the bound-bound opacity of the heavy elements. Hence, a detailed opacity is necessary to model the realistic kilonova light curve and spectra. However, such calculations for opacity, and correspondingly, the realistic light curve, were largely unavailable, especially for the condition suitable at an early time (t < 1 day).
> In my talk, I will discuss recent developments and challenges in modelling kilonova light curves. Also, I will share my recent work on opacity and light curve calculations of the kilonova, focusing on early time (t < 1 day).
> ———————————
> 
> We look forward to seeing many of you there. Thanks!
> 
> Eliot and Kris
> 
> 
> 
> Upcoming Events:
> 
> 2023-01-27	Mingjie Jian (SU)
> 2023-02-03	Kelley Hess (IAA - Granada, Spain)
> 2023-02-10	No seminar - OKC day
> 2023-02-17	Diane Feuillet (Lund Obs.)
> 
> 
> ———————————
> Topic: Astronomy Department Seminar Smaranika Banerjee
> Time: Jan 20th, 2023 10:30 AM Stockholm
> 
> Join Zoom Meeting:
> https://stockholmuniversity.zoom.us/s/61002076352 <https://stockholmuniversity.zoom.us/s/61002076352>
> Meeting ID: 610 0207 6352

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