scholarly journals A First Look at the Disk Population in the Auriga-California Molecular Cloud

2013 ◽  
Vol 8 (S299) ◽  
pp. 151-152
Author(s):  
Hannah Broekhoven-Fiene ◽  
Brenda C. Matthews ◽  
Paul M. Harvey ◽  
Keyword(s):  
Grain Growth ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Planet Formation ◽  
Circumstellar Disks ◽  
The Other ◽  
Giant Molecular Clouds ◽  
Formation Potential

AbstractThe Auriga-California Molecular Cloud (AMC) is one of two nearby (within 500 pc) giant molecular clouds, the other being the Orion A Molecular Cloud (OMC). We aim to study the properties of circumstellar disks in the AMC to compare the planet formation potential and processes within the AMC to those for other clouds. A first look with measurements from Spitzer observations suggests that AMC disk properties, such as the distribution of disk luminosities and the evolution of the mid-IR excesses, are not vastly different from those in other regions. Follow-up observations in the submm, mm and cm can be used to measure disk masses and the degree of grain growth from spectral slopes to more completely characterize the disk population.

scholarly journals CO observations of spiral structure and the lifetime of giant molecular clouds

1979 ◽  
Vol 84 ◽  
pp. 277-283
Author(s):  
N. Z. Scoville ◽  
P. M. Solomon ◽  
D. B. Sanders
Keyword(s):  
Molecular Cloud ◽  
Mass Fraction ◽  
Molecular Clouds ◽  
Spiral Structure ◽  
Large Mass ◽  
Giant Molecular Clouds ◽  
Spiral Pattern ◽  
The Galaxy ◽  
Co Emission ◽  
Co Observations

Observations of CO emission at ℓ=0 to 70°, |b| ≤ 1° are analyzed to give a map of the molecular cloud distribution in the galaxy as viewed from the galactic pole. From the fact that this distribution shows no obvious spiral pattern we conclude that the giant molecular clouds sampled in the CO line are situated in both arm and interarm regions and they must last more than 108 years. A similar age estimate is deduced from the large mass fraction of H2 in the interstellar medium in the interior of the galaxy. An implication of this longevity is that the great masses of these clouds may be accumulated through cloud-cloud collisions of originally smaller clouds.

scholarly journals GRB PROMPT OPTICAL/UV EMISSION AND DUST SUBLIMATION

2013 ◽  
Vol 23 ◽  
pp. 198-201
Author(s):  
XIAO-HONG CUI ◽  
ZHUO LI ◽  
LI-PING XIN
Keyword(s):  
Molecular Cloud ◽  
Molecular Clouds ◽  
Massive Stars ◽  
The Other ◽  
Dust Extinction ◽  
Delayed Onset ◽  
Uv Emission ◽  
The Future ◽  
Γ Ray ◽  
Fast Rise

Observations imply that long γ-ray bursts (GRBs) are originated from explosions of massive stars, therefore they may occur in the molecular clouds where their progenitors were born. We show here that the prompt optical-UV emission from GRBs may be delayed due to the dust extinction, which can well explain the observed optical delayed onset and fast rise in GRB 080319B. The density and the size of the molecular cloud around GRB 080319B are roughly constrained to be ~ 103cm-3 and ~ 8pc, respectively. We also investigate the other GRBs with prompt optical-UV data, and find similar values of the densities and sizes of the local molecular clouds. The future observations of prompt optical-UV emission from GRBs in subsecond timescale, e.g., by UFFO-Pathfinder and SVOM-GWAC, will provide more evidence and probes of the local GRB environments.

scholarly journals Giant Molecular Clouds and Cluster Formation

2002 ◽  
Vol 207 ◽  
pp. 499-504
Author(s):  
Mónica Rubio
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Cluster Formation ◽  
Present Knowledge ◽  
Magellanic Clouds ◽  
Giant Molecular Clouds ◽  
Cloud Properties

We will review the present knowledge of molecular cloud properties and its relation to star formation. We will discuss the evidence for cluster formation associated with giant molecular clouds, and will concentrate on recent results in our Galaxy and the Magellanic Clouds.

scholarly journals Detection of Interarm Molecular Clouds in M51: MSC OR GMC?

1994 ◽  
Vol 140 ◽  
pp. 355-356
Author(s):  
T. Tosaki ◽  
Y. Taniguchi ◽  
R. Kawabe
Keyword(s):  
Spiral Galaxy ◽  
Spectral Resolution ◽  
Molecular Clouds ◽  
Spiral Galaxies ◽  
The Other ◽  
High Spectral Resolution ◽  
Molecular Gas ◽  
Giant Molecular Clouds ◽  
The Difference ◽  
Resolution Study

In our Galaxy, molecular gas forms clouds with masses of ~ 105M© and with sizes of several 10 pc, which are called Giant Molecular Clouds (Sanders 1985; hereafter GMCs). Such GMCs are also observed in nearby spiral galaxies M31 and M33 (Lada et al. 1988; Wilson & Scoville 1990). On the other hand, one of the well-studied spiral galaxy M51 has more massive and larger molecular clouds. Since their typical mass and size are 107-8MQ and several 100 pc, respectively, they are called Molecular Superclouds (Rand & Kulkarni 1990; Tosaki et al. 1992; hereafter, MSCs). A question arises as what causes the difference in structural properties of molecular gas among the spiral galaxies. In order to answer this question, we should make higher resolution studies both spatially and spectroscopically. In this paper, we present the results of high spectral-resolution study of the MSCs in M51 based on the 12CO (J = 1 − 0) mapping made with the Nobeyama Millimeter Array (Tosaki et al. 1992). The spatial resolution is 5.”3×4.”9 corresponding to 240 × 230 pc at distance of 9.6 Mpc. The spectral resolution is 3.25 km s−1. The analysis is made for the 1’ region whose center is offset 42” south and 7” east from the nucleus, because a very intense molecular arm is present in this region. Our Main results and conclusions are as follows.

scholarly journals Structure and Conditions in Massive Star Forming Giant Molecular Clouds

2002 ◽  
Vol 12 ◽  
pp. 140-142
Author(s):  
Jonathan Williams
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Massive Star ◽  
Massive Stars ◽  
The Other ◽  
Giant Molecular Clouds ◽  
Star Forming ◽  
Millimeter Wavelength ◽  
Formation And Evolution ◽  
Self Similar

AbstractMassive stars form in clusters within self-gravitating molecular clouds. The size scale of these clusters is sufficiently large that non-thermal, or turbulent, motions of the gas must be taken into account when considering their formation. Millimeter wavelength radio observations of the gas and dust in these clouds reveal a complex, self-similar structure that reflects the turbulent nature of the gas. Differences are seen, however, towards dense bound cores in proto-clusters. Examination of the kinematics of gas around such cores suggests that dissipation of turbulence may be the first step in the star formation process. Newly formed stars, on the other hand, replenish turbulence through their winds and outflows. In this way, star formation may be self-regulated. Observations and simulations are beginning to demonstrate the key role that cloud turbulence plays in the formation and evolution of stellar groups.

scholarly journals Star Formation in the LMC: Comparative CCD Observations of Young Stellar Populations in two Giant Molecular Clouds

2009 ◽  
Vol 5 (S262) ◽  
pp. 424-425
Author(s):  
Jan Ruppert ◽  
Hans Zinnecker
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Near Infrared ◽  
Large Magellanic Cloud ◽  
The Other ◽  
High Mass ◽  
Giant Molecular Clouds ◽  
Stellar Content ◽  
Control Field ◽  
Low Mass

AbstractThis work deals with a CCD imaging study at optical and near-infrared wavelength of two giant molecular clouds (plus a control field) in the southern region of the Large Magellanic Cloud, one of which shows multiple signs of star formation, whereas the other does not. The observational data from VLT FORS2 (R-band) and NTT SOFI (Ks-band) have been analyzed to derive luminosity functions and color-magnitude diagrams. The young stellar content of these two giant molecular clouds is compared and confirmed to be different, in the sense that the apparently “starless” cloud has so far formed only low-luminosity, low-mass stars (fainter than mKs = 16.5 mag, not seen by 2MASS), while the other cloud has formed both faint low-mass and luminous high-mass stars. The surface density excess of low-luminosity stars (~ 2 per square arcmin) in the “starless” cloud with respect to the control field is about 20% whereas the excess is about a factor of 3 in the known star-forming cloud. The difference may be explained theoretically by the gravo-turbulent evolution of giant molecular clouds, one being younger and less centrally concentrated than the other.

scholarly journals Anatomy of Orion Molecular Clouds—The Astrochemistry Perspective/Approach

2021 ◽  
Vol 8 ◽  
Author(s):  
Dipen Sahu ◽  
Sheng-Yuan Liu ◽  
Tie Liu
Keyword(s):  
Molecular Cloud ◽  
Molecular Clouds ◽  
Large Scale ◽  
Chemical Species ◽  
Young Stellar Objects ◽  
Giant Molecular Clouds ◽  
Stellar Objects ◽  
Chemical Conditions ◽  
Cloud Cores ◽  
Physical And Chemical

The Orion molecular cloud (OMC) complex is the nearest and perhaps the best-studied giant molecular cloud complex within which low-mass and massive star formation occur. A variety of molecular species, from diatomic molecules to complex organic molecules (COMs), have been observed in the OMC regions. Different chemical species are found at different scales—from giant molecular clouds at parsec scales to cloud cores around young stellar objects at hundreds of au scales, and they act as tracers of different physical and chemical conditions of the sources. The OMC, therefore, is an ideal laboratory for studying astrochemistry over a broad spectrum of molecular cloud structures and masses. In this review, we discuss the usage of astrochemistry/molecular tracers and (sub) millimeter observations to understand the physical and chemical conditions of large-scale molecular clouds, filaments, and clumps down to cores and protostars in the OMC complex as a demonstration case.

scholarly journals An Investigation of the Molecular Clouds of the Carina HII Region/Molecular Cloud Complex—First Results

1998 ◽  
Vol 15 (2) ◽  
pp. 202-207 ◽  
Author(s):  
K. J. Brooks ◽  
J. B. Whiteoak ◽  
J. W. V. Storey
Keyword(s):  
Molecular Cloud ◽  
Molecular Clouds ◽  
Massive Stars ◽  
Molecular Gas ◽  
Hii Region ◽  
Carina Nebula ◽  
First Results ◽  
Multi Wavelength ◽  
Cloud Complex

AbstractThe Carina Nebula is an extremely bright southern HII region embedded in a giant molecular cloud and contains some of the most massive stars known in our Galaxy. We are undertaking a multi-wavelength study of the Carina Nebula in order to examine the detailed kinematics and distribution of the molecular and ionised gas, and to look for further evidence of ongoing star formation. Here we present the results of the initial molecular cloud observations which were made by observing the 12CO(1−0) emission with the Mopra antenna. The observations reveal the clumpy morphology of the molecular gas, and allow us to identify many interesting regions for follow-up observations.

The Influence of the Established Links between University Courses on the Quality of Teaching

2018 ◽  
Vol 8 (2) ◽  
pp. 35-48
Author(s):  
Jiří Rybička ◽  
Petra Čačková
Keyword(s):  
Higher Education ◽  
Empirical Study ◽  
The Other ◽  
Coherent System ◽  
University Courses ◽  
Quality Of Teaching ◽  
Education Courses ◽  
Initial Knowledge

One of the tools to determine the recommended order of the courses to be taught is to set the prerequisites, that is, the conditions that have to be fulfilled before commencing the study of the course. The recommended sequence of courses is to follow logical links between their logical units, as the basic aim is to provide students with a coherent system according to the Comenius' principle of continuity. Declared continuity may, on the other hand, create organizational complications when passing through the study, as failure to complete one course may result in a whole sequence of forced deviations from the recommended curriculum and ultimately in the extension of the study period. This empirical study deals with the quantitative evaluation of the influence of the level of initial knowledge given by the previous study on the overall results in a certain follow-up course. In this evaluation, data were obtained that may slightly change the approach to determining prerequisites for higher education courses.

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