August 8 Tue 10:00-11:00 SOKENDAI Doctoral Thesis Preliminary Evaluation Zoom / Lecture Room (hybrid)
August 9 Wed 15:30-16:30 NAOJ Science Colloquium
Zoom / Large Seminar Room (hybrid)
詳細は下記からご覧ください。
=============== August 8 Tue===============
Campus：Mitaka
Seminar：SOKENDAI Doctoral Thesis Preliminary Evaluation 総研大博士学位論文予備審査会
Regularly Scheduled/Sporadic：Sporadic
Date and time：August 8, 2023, 10:00～11:00
Place：Lecture Room and Zoom
Speaker：Nao Fukagawa
Title：Chemical Evolution of Dwarf Galaxies
Facilitator
-Name：Hideyuki Kobayashi
:Natsuko Fujii (Graduate Student Affairs Unit)
=============== August 9 Wed===============
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2023 Aug. 9, 15:30-16:30
Place：Zoom / the large seminar room (hybrid)
Speaker：Lars Bonne
Affiliation：SOFIA Science Center, USRA, NASA Ames
Title：The assembly and dispersal of dense gas in star forming regions
Abstract：
First, I will present work analyzing multiple spectral lines toward
low- and high-mass star forming regions. The study employs archival HI
data, CO observations from the NANTEN2, APEX, and IRAM 30m
observatories, and [CII] observations with the SOFIA telescope. In these
regions we demonstrated the presence of recurring organized velocity
fields, also found by other authors, which suggests that star formation
is initiated by the same mechanism. Namely, magnetic field bending in
high-velocity (>7 km/s) colliding flows. This appears to be consistent
with magnetic field observations in several nearby clouds, which
suggests that the proposed scenario might be widespread and explain both
low- and high-mass star formation.
In the second part, I will present observations of the [CII] spectral
line by the FEEDBACK legacy program toward ~10 ionized (HII) regions
surrounding massive O stars. [CII] is the main coolant of the neutral
ISM in photodissociation regions (PDRs) and thus an excellent probe to
study the effect of stellar feedback on the host molecular cloud. The
[CII] emission reveals previously undetected high-velocity gas (10-20
km/s) in all regions. This high-velocity gas is the result of expanding
bubbles and continuous mass ejection in flattened molecular clouds. The
detection of this high-velocity gas has reignited the discussion whether
radiation or stellar winds drive molecular dispersal. Quantifying the
mass ejection rates also allows us to make a direct estimate of
molecular cloud dispersal timescales which consistently points to a few
(< 5) Myr. This provides direct observational evidence that molecular
cloud are transient structures and not in quasi-static equilibrium.
Facilitator
-Name：Doris Arzoumanian
-Comment：English