[Astronomy seminar] Astronomy Department Seminar - September 17th Nushkia Chamba

[Astronomy seminar announcements]

Hello

On Friday the 17h we have the third astronomy seminar of the year with 
our own Nushkia Chamba (Stockholm University) speaking via Zoom at 10:30.

*Unveiling the outskirts of galaxies using deep imaging *

The traditional measurement of the size of galaxies, the effective 
radius, is a relic of the epoch when shallow imaging was unable to 
capture the full extension of astronomical sources. However, current 
deep imaging surveys have revolutionised our view of galaxies and the 
characteristics of their faint outskirts, allowing us to regard 
critically our own conventions. From this perspective, it is time to 
move from a size definition based on the light concentration of 
galaxies, the effective radius, to a definition that intuitively 
captures the concept of the size of galaxies, such as its edge or 
boundary. In this talk, a physically motivated definition for the size 
of a galaxy based on the gas density threshold value for star formation 
in galaxies is studied. Remarkably, the new size definition not only 
captures what the human visual system identifies as the edge of a 
galaxy, but also dramatically decreases the scatter in the stellar 
mass–size relation by more than a factor of two. Compared to other size 
measures, the new parameter is unique in that it also unifies galaxies 
spanning five orders of magnitude in stellar mass on a single mass–size 
relationship. To place this discovery in the context of galaxy formation 
and evolution, its application is discussed on the understanding of the 
origin of discs and the nature of ultra-diffuse galaxies.

We are trying something new this year with leaving the Zoom call open 
after the formal hour of the seminar is up to allow the speaker, if they 
wish, to chat informally with anyone who is interested.

Thanks

Chris and Tine

Christopher Usher is inviting you to a scheduled Zoom meeting.

Topic: Astronomy Department Seminar - Nushkia Chamba
Time: Sep 17, 2021 10:30 AM Stockholm

Join Zoom Meeting
https://stockholmuniversity.zoom.us/j/68003268702?pwd=Q085dHZrT0Y0djZHelZNL3RVb2x0Zz09 


Meeting ID: 680 0326 8702
Passcode: eRmiTeXA
One tap mobile
46844682488,,68003268702

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.su.se/pipermail/seminars-announce.astro-at-su.se/attachments/20210913/7d58fd38/attachment.html>