scholarly journals A Possible Molecular Counterpart to the G359.54+0.18 Non-Thermal Filaments

1989 ◽  
Vol 136 ◽  
pp. 189-193
Author(s):  
John Bally ◽  
Farhad Yusef-Zadeh ◽  
J. M. Hollis
Keyword(s):  
Molecular Cloud ◽  
Galactic Center ◽  
Molecular Gas ◽  
Thermal Radio ◽  
Co Observations

We present new 30″ resolution J=2–1 12CO observations of the molecular gas located close to a group of non-thermal radio emitting filaments recently detected near the Galactic center (Bally and Yusef-Zadeh, 1989). The new data provide some support for the association of the non-thermal filaments G359.54+0.18 with the projected edge of a molecular cloud.

scholarly journals CO (J=2-1) Observations of the Molecular Cloud Complex in the Galactic Center

1994 ◽  
Vol 140 ◽  
pp. 168-169
Author(s):  
Tomoharu Oka ◽  
Tetsuo Hasegawa ◽  
Masahiko Hayashi ◽  
Toshihiro Handa ◽  
Sei'ichi Sakamoto
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Large Scale ◽  
Galactic Center ◽  
Molecular Gas ◽  
Star Forming ◽  
Near Future ◽  
Cloud Complex ◽  
Mapping Observation

AbstractWe report a large scale mapping observation of the Galactic center region in the CO (J=2-1) line using the Tokyo-NRO 60cm survey telescope. Distribution of the CO (J=2-1) emission in the I-V plane suggests that molecular clouds forms a huge complex (Nuclear Molecular cloud Complex, NMC). Tracers of star formation activities in the last 106-108 years show that star formation has occured in a ring ~ 100 pc in radius. Relative to this Star Forming Ring, the molecular gas is distributed mainly on the positive longitude side. This may indicate that much of the gas in NMC is in transient orbit to fall into the star forming ring or to the nucleus in the near future.

scholarly journals Rapid gas fueling in a barred potential by self-gravitational instability

1993 ◽  
Vol 153 ◽  
pp. 285-286
Author(s):  
Keiichi Wada ◽  
Asao Habe
Keyword(s):  
Galactic Center ◽  
Gravitational Instability ◽  
High Mass ◽  
Molecular Gas ◽  
Supply Rate ◽  
Triggering Mechanism ◽  
Star Forming ◽  
Star Forming Regions ◽  
Central Regions ◽  
Co Observations

Recent IRAS surveys have revealed that large infrared luminosities are originated from active star forming regions in galaxies (Soifer et al. 1986). Such starburst regions are frequently located in galactic central regions and CO observations indicate that these regions contain a large amount of molecular gas (e.g. Ishizuki et al. 1990). However, the triggering mechanism for starbursts and the mechanism of the high mass supply rate of gas into a galactic center are still unclear.

scholarly journals The Molecular Cloud Content of Spiral and Dwarf Galaxies

1986 ◽  
Vol 7 ◽  
pp. 519-524
Author(s):  
L. J Rickard
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Massive Star ◽  
Spiral Structure ◽  
Dwarf Galaxies ◽  
Molecular Gas ◽  
Molecular Component ◽  
Massive Star Formation ◽  
Co Observations

AbstractThis paper concentrates on the molecular cloud component in its role as the site of current star formation – especially massive star formation. It is further restricted to the molecular component as traced by CO, the preeminent tracer of molecular gas in galaxies despite the problems discussed here. The basic topics addressed are (1) the variation of CO properties with galactic environment and type; (2) the problems involved in the inference of H2 distributions for individual galaxies from CO observations; and (3) the particular question of the presence of spiral structure in the CO component.

scholarly journals Low frequency (74 MHz) radio continuum observations of the inner 13° × 7° of the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 464-466
Author(s):  
M. Rickert ◽  
F. Yusef-Zadeh ◽  
C. Brogan
Keyword(s):  
High Resolution ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Galactic Center ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Image Displays ◽  
Western Side

AbstractWe analyze a high resolution (114″ × 60″) 74 MHz image of the Galactic center taken with the Very Large Array (VLA). We have identified several absorption and emission features in this region, and we discuss preliminary results of two Galactic center sources: the Sgr D complex (G1.1–0.1) and the Galactic center lobe (GCL).The 74 MHz image displays the thermal and nonthermal components of Sgr D and we argue the Sgr D supernova remnant (SNR) is consistent with an interaction with a nearby molecular cloud and the location of the Sgr D Hii region on the near side of the Galactic center. The image also suggests that the emission from the eastern side of the GCL contains a mixture of both thermal and nonthermal sources, whereas the western side is primarily thermal.

scholarly journals 5.18. Molecular gas in the poststarburst galaxy NGC7331

1998 ◽  
Vol 184 ◽  
pp. 247-248
Author(s):  
T. Tosaki ◽  
Y. Shioya
Keyword(s):  
High Resolution ◽  
Spiral Galaxy ◽  
Stellar Populations ◽  
Optical Spectra ◽  
Molecular Gas ◽  
Early Type ◽  
Origin And Evolution ◽  
Co Observations

To understand the origin and evolution of starburst activity, we must study the full evolution of starburst; i.e., pre-, on-going, and post-starburst phases. It seems reasonable to suppose the numerous A-type stars indicate past starburst and they show strong Balmer absorption. NGC7331, nearby early-type spiral galaxy, is one of the poststarburst galaxies which show strong Balmer absorption. The optical spectra of NGC7331 were dominated by component of intermediate-age (5 × 109 years) stellar populations (Ohyama & Taniguchi 1996). We present the result of the high resolution CO observations of NGC7331 using Nobeyama Milimeter Array.

scholarly journals Evidence for feedback and stellar-dynamically regulated bursty star cluster formation: the case of the Orion Nebula Cluster

2018 ◽  
Vol 612 ◽  
pp. A74 ◽  
Author(s):  
Pavel Kroupa ◽  
Tereza Jeřábková ◽  
František Dinnbier ◽  
Giacomo Beccari ◽  
Zhiqiang Yan
Keyword(s):  
Molecular Cloud ◽  
Massive Stars ◽  
Cluster Formation ◽  
Life Time ◽  
Molecular Gas ◽  
Orion Nebula ◽  
Main Sequence Stars ◽  
Sequence Of Events ◽  
Proposed Model ◽  
Magnitude Diagram

A scenario for the formation of multiple co-eval populations separated in age by about 1 Myr in very young clusters (VYCs, ages less than 10 Myr) and with masses in the range 600–20 000 M⊙ is outlined. It rests upon a converging inflow of molecular gas building up a first population of pre-main sequence stars. The associated just-formed O stars ionise the inflow and suppress star formation in the embedded cluster. However, they typically eject each other out of the embedded cluster within 106 yr, that is before the molecular cloud filament can be ionised entirely. The inflow of molecular gas can then resume forming a second population. This sequence of events can be repeated maximally over the life-time of the molecular cloud (about 10 Myr), but is not likely to be possible in VYCs with mass <300 M⊙, because such populations are not likely to contain an O star. Stellar populations heavier than about 2000 M⊙ are likely to have too many O stars for all of these to eject each other from the embedded cluster before they disperse their natal cloud. VYCs with masses in the range 600–2000 M⊙ are likely to have such multi-age populations, while VYCs with masses in the range 2000–20 000 M⊙ can also be composed solely of co-eval, mono-age populations. More massive VYCs are not likely to host sub-populations with age differences of about 1 Myr. This model is applied to the Orion Nebula Cluster (ONC), in which three well-separated pre-main sequences in the colour–magnitude diagram of the cluster have recently been discovered. The mass-inflow history is constrained using this model and the number of OB stars ejected from each population are estimated for verification using Gaia data. As a further consequence of the proposed model, the three runaway O star systems, AE Aur, μ Col and ι Ori, are considered as significant observational evidence for stellar-dynamical ejections of massive stars from the oldest population in the ONC. Evidence for stellar-dynamical ejections of massive stars in the currently forming population is also discussed.

The Warm Molecular Gas in the Galactic Center

2002 ◽  
pp. 331-332
Author(s):  
N. J. Rodríguez-Fernández ◽  
J. Martín-Pintado ◽  
P. De Vicente ◽  
A. Fuente
Keyword(s):  
Galactic Center ◽  
Molecular Gas

scholarly journals CO and the Multiphase ISM

1997 ◽  
Vol 170 ◽  
pp. 25-32
Author(s):  
Christopher F. Mckee
Keyword(s):  
Mach Number ◽  
Magnetic Fields ◽  
Interstellar Medium ◽  
Molecular Clouds ◽  
Molecular Gas ◽  
Wave Pressure ◽  
Multiphase Structure ◽  
Co Observations

CO observations indicate that molecular clouds have a complex multiphase structure, and this is compared with the multiphase structure of the diffuse interstellar medium. The trace ionization within the molecular gas is governed primarily by UV photoionization. Magnetic fields contribute a significantly larger fraction of the pressure in molecular clouds than in the diffuse interstellar medium. Observations suggest that the total Alfvén Mach number, mAtot, of the turbulence in the diffuse ISM exceeds unity; Zeeman observations are consistent with mAtot ≲ 1 in molecular clouds, but more data are needed to verify this. Most molecular clouds are self-gravitating, and they can be modeled as multi-pressure polytropes with thermal, magnetic, and wave pressure. The pressure and density within self-gravitating clouds is regulated by the pressure in the surrounding diffuse ISM.

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