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<p>Reminder of Nushkia's seminar in ~35 min<br>
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<div class="moz-cite-prefix">On 13/09/2021 11:11, Chris Usher wrote:<br>
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cite="mid:ade3c82b-3db6-598b-296c-44de75db4c0d@astro.su.se">
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<p>Hello</p>
<p>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.</p>
<p><b>Unveiling the outskirts of galaxies using deep imaging </b>
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<p class=""><span style="font-size: 11pt;" class="">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.</span></p>
<p>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.</p>
Thanks<br>
<p> Chris and Tine</p>
<p>Christopher Usher is inviting you to a scheduled Zoom
meeting. <br>
<br>
Topic: Astronomy Department Seminar - Nushkia Chamba <br>
Time: Sep 17, 2021 10:30 AM Stockholm <br>
<br>
Join Zoom Meeting <br>
<a class="moz-txt-link-freetext"
href="https://stockholmuniversity.zoom.us/j/68003268702?pwd=Q085dHZrT0Y0djZHelZNL3RVb2x0Zz09"
moz-do-not-send="true">https://stockholmuniversity.zoom.us/j/68003268702?pwd=Q085dHZrT0Y0djZHelZNL3RVb2x0Zz09</a>
<br>
<br>
Meeting ID: 680 0326 8702 <br>
Passcode: eRmiTeXA <br>
One tap mobile <br>
46844682488,,68003268702</p>
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