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The Subaru Seminar is
usually held in Room 104 of the Hilo Base Facility, adjacent
to the main lobby. Everyone is welcome to attend. If you are
interested in giving a seminar, please contact Subaru seminar organizers
(Tae-Soo Pyo, Sherry Yeh, Nagayoshi Ohashi)
by email : sseminar_at_subaru.naoj.org (please change"_at" to @).
July 28, Monday, at 11:00 am
" The Galaxy Champagne "
Nicolas Flagey
(IfA Hilo)
Over 400 small (a few 10") rings, disks and shells have been
discovered from visual inspection of the Spitzer /MIPSGAL 24 um mosaic
images. These MIPSGAL bubbles (MBs) are pervasive through the entire
Galactic plane in the mid-infrared. They span a large range of
morphologies, sizes and fluxes. The analysis of near- to far-IR
broadband images has unveiled that 54 MBs (about 13%) have central
sources at 24 um while this number rises to at least 100 in the IRAC
or 2MASS images. The extended emission is detected in about two thirds
of the MBs at 70um but less than one third at any other IR
wavelengths. When we published the catalog, only 15% of the MBs were
identified or associated with stars of known spectral types. Most of
the known MBs were associated with planetary nebulae while a few were
supernova remnants, Wolf-Rayet stars (WR), luminous blue variables
(LBV) and other emission line stars. The MBs are thus suspected to be
associated with stars in their late stages of evolution, with at least
a fraction of them being massive. In this talk, I will address the two
main questions arising from this discovery: (1) what are the MBs? and
(2) what is the origin of their emission? I will first present the
catalog of the MBs and their general properties, in terms of
morphologies, sizes, and broadband fluxes. In particular, I will show
that mid to far-IR observations from the Spitzer and Herschel Galactic
plane surveys provide a direct measurement of the dust mass ejected by
the MBs. Then, I will detail some of the many follow-up observations
we obtained to identify the origin of the mid-IR emission and the
nature of the unknown objects. I will focus on: (1) unique Spitzer/IRS
observations of 14 MBs that lead to the discovery of several highly
excited, dust poor planetary nebulae, and several dust rich, massive
star candidates; and (2) Palomar and VLT near-IR observations of
central sources in MB, that reveal a large number of new massive
stars. I will discuss other paths we are exploring, from radio to
optical. I will summarize the results of these investigations and
discuss their relevance for the complete catalog.
Seminars are also held at JAC,
CFHT,
and IfA.
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