Log in

Relevant bibliographies by topics / Molecular clouds / Journal articles

To see the other types of publications on this topic, follow the link: Molecular clouds.

Journal articles on the topic 'Molecular clouds'

Author: Grafiati

Published: 4 June 2021

Last updated: 26 October 2024

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Molecular clouds.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Sullivan, Colin H., L. M. Fissel, P. K. King, C.-Y. Chen, Z.-Y. Li, and J. D. Soler. "Characterizing the magnetic fields of nearby molecular clouds using submillimeter polarization observations." Monthly Notices of the Royal Astronomical Society 503, no. 4 (March 16, 2021): 5006–24. http://dx.doi.org/10.1093/mnras/stab596.

Full text

Abstract:

ABSTRACT Of all the factors that influence star formation, magnetic fields are perhaps the least well understood. The goal of this paper is to characterize the 3D magnetic field properties of nearby molecular clouds through various methods of statistically analysing maps of polarized dust emission. Our study focuses on nine clouds, with data taken from the Planck Sky Survey as well as data from the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry observations of Vela C. We compare the distributions of polarization fraction (p), dispersion in polarization angles ($\mathcal {

APA, Harvard, Vancouver, ISO, and other styles

2

Clube, S. V. M. "Molecular clouds: comet factories?" International Astronomical Union Colloquium 83 (1985): 19–30. http://dx.doi.org/10.1017/s0252921100083779.

Full text

Abstract:

AbstractRecent discoveries seem to indicate a catastrophic history of terrestrial evolution, explicable in terms of Oort cloud disturbance by molecular clouds in the Galactic disc. The problem of Oort cloud replenishment thus assumes considerable significance and reasons are given for supposing comet exchange takes place during actual penetration of molecular clouds. The number density of comets in molecular clouds, thereby implied, seems to suggest primary condensations of ≤103km in a dense precursor state of spiral arms. If chemical and/or isotopic signatures of comets should indicate an ext

APA, Harvard, Vancouver, ISO, and other styles

3

Bot, Caroline, Mónica Rubio, François Boulanger, Marcus Albrecht, Frank Bertoldi, Alberto D. Bolatto, and Adam K. Leroy. "Tracing the cold molecular gas reservoir through dust emission in the SMC." Proceedings of the International Astronomical Union 4, S256 (July 2008): 148–53. http://dx.doi.org/10.1017/s174392130802838x.

Full text

Abstract:

AbstractThe amount of molecular gas is a key for understanding the future star formation in a galaxy. However, this quantity is difficult to infer as the cold H2 is almost impossible to observe and, especially at low metallicities, CO only traces part of the clouds, keeping large envelopes of H2 hidden from observations. In this context, millimeter dust emission tracing the cold and dense regions can be used as a tracer to unveil the total molecular gas masses. I present studies of a sample of giant molecular clouds in the Small Magellanic Cloud. These clouds have been observed in the millimet

APA, Harvard, Vancouver, ISO, and other styles

4

Blitz, Leo. "Molecular Clouds at High z." Symposium - International Astronomical Union 144 (1991): 41–51. http://dx.doi.org/10.1017/s0074180900088896.

Full text

Abstract:

The evidence for the existence of molecular clouds at large distances from the Galactic plane is reviewed. The molecular clouds at high Galactic latitudes are shown to be largely confined to the Galactic plane. There is evidence for one giant molecular cloud as much as four scale heights from the Galactic plane, but given the sample size from which the cloud is drawn, it is reasonable to suppose that it is part of the tail of the thin disk population. There is weak evidence that one star-forming molecular cloud may have originated in the Galactic halo. On the basis of kinematic evidence howeve

APA, Harvard, Vancouver, ISO, and other styles

5

Wong, Tony, Annie Hughes, Jürgen Ott, Jorge L. Pineda, and Erik Muller. "The Molecular Cloud Population of the Large Magellanic Cloud." Proceedings of the International Astronomical Union 8, S292 (August 2012): 71–74. http://dx.doi.org/10.1017/s1743921313000495.

Full text

Abstract:

AbstractWe have mapped an extensive sample of molecular clouds in the Large Magellanic Cloud (LMC) at 11 pc resolution in the CO(1-0) line as part of the Magellanic Mopra Assessment (MAGMA). We identify clouds as regions of connected CO emission and determine their sizes, line widths, and fluxes. We find that GMCs are not preferentially located in regions of high Hi line width or velocity gradient, and that there is no clear Hi column density threshold for CO detection. The luminosity function of CO clouds is steeper than dN/dL ∝ L−2, suggesting a substantial fraction of mass in low-mass cloud

APA, Harvard, Vancouver, ISO, and other styles

6

Körtgen, Bastian. "The turbulence driving parameter of molecular clouds in disc galaxies." Monthly Notices of the Royal Astronomical Society 497, no. 1 (July 24, 2020): 1263–74. http://dx.doi.org/10.1093/mnras/staa2028.

Full text

Abstract:

ABSTRACT Supersonic turbulence plays a pivotal role during the formation of molecular clouds and stars in galaxies. However, little is known about how the fraction of compressive and solenoidal modes in the velocity field evolves over time and how it depends on properties of the molecular cloud or the galactic environment. In this work, we carry out magnetohydrodynamical simulations of disc galaxies and study the time evolution of the turbulence driving parameter for an ensemble of clouds. We find that the time-averaged turbulence driving parameter is insensitive to the position of the cloud w

APA, Harvard, Vancouver, ISO, and other styles

7

Li, Pak Shing, and Richard I. Klein. "Magnetized interstellar molecular clouds – II. The large-scale structure and dynamics of filamentary molecular clouds." Monthly Notices of the Royal Astronomical Society 485, no. 4 (March 27, 2019): 4509–28. http://dx.doi.org/10.1093/mnras/stz653.

Full text

Abstract:

Abstract We perform ideal magnetohydrodynamics high-resolution adaptive mesh refinement simulations with driven turbulence and self-gravity and find that long filamentary molecular clouds are formed at the converging locations of large-scale turbulence flows and the filaments are bounded by gravity. The magnetic field helps shape and reinforce the long filamentary structures. The main filamentary cloud has a length of ∼4.4 pc. Instead of a monolithic cylindrical structure, the main cloud is shown to be a collection of fibre/web-like substructures similar to filamentary clouds such as L1495. Un

APA, Harvard, Vancouver, ISO, and other styles

8

Braine, J., E. Rosolowsky, P. Gratier, E. Corbelli, and K. F. Schuster. "Properties and rotation of molecular clouds in M 33." Astronomy & Astrophysics 612 (April 2018): A51. http://dx.doi.org/10.1051/0004-6361/201732405.

Full text

Abstract:

The sample of 566 molecular clouds identified in the CO(2–1) IRAM survey covering the disk of M 33 is explored in detail. The clouds were found using CPROPS and were subsequently catalogued in terms of their star-forming properties as non-star-forming (A), with embedded star formation (B), or with exposed star formation (C, e.g., presence of Hα emission). We find that the size-linewidth relation among the M 33 clouds is quite weak but, when comparing with clouds in other nearby galaxies, the linewidth scales with average metallicity. The linewidth and particularly the line brightness decrease

APA, Harvard, Vancouver, ISO, and other styles

9

Yan, Qing-Zeng, Ji Yang, Yang Su, Yan Sun, Xin Zhou, Ye Xu, Hongchi Wang, Shaobo Zhang, and Zhiwei Chen. "Dependence of Molecular Cloud Samples on Angular Resolution, Sensitivity, and Algorithms." Astronomical Journal 164, no. 2 (July 18, 2022): 55. http://dx.doi.org/10.3847/1538-3881/ac77ea.

Full text

Abstract:

Abstract In this work, we investigate the observational and algorithmic effects on molecular cloud samples identified from position–position–velocity (PPV) space. By smoothing and cutting off the high quality data of the Milky Way Imaging Scroll Painting (MWISP) survey, we extract various molecular cloud samples from those altered data with the DBSCAN (density-based spatial clustering of applications with noise) algorithm. Those molecular cloud samples are subsequently used to gauge the significance of sensitivity, angular/velocity resolution, and DBSCAN parameters. Two additional surveys, the

APA, Harvard, Vancouver, ISO, and other styles

10

Duarte-Cabral, A., D. Colombo, J. S. Urquhart, A. Ginsburg, D. Russeil, F. Schuller, L. D. Anderson, et al. "The SEDIGISM survey: molecular clouds in the inner Galaxy." Monthly Notices of the Royal Astronomical Society 500, no. 3 (September 11, 2020): 3027–49. http://dx.doi.org/10.1093/mnras/staa2480.

Full text

Abstract:

ABSTRACT We use the 13CO (2–1) emission from the SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium) high-resolution spectral-line survey of the inner Galaxy, to extract the molecular cloud population with a large dynamic range in spatial scales, using the Spectral Clustering for Interstellar Molecular Emission Segmentation (scimes) algorithm. This work compiles a cloud catalogue with a total of 10 663 molecular clouds, 10 300 of which we were able to assign distances and compute physical properties. We study some of the global properties of clouds using a

APA, Harvard, Vancouver, ISO, and other styles

11

Kutner, Marc L., and Kathryn N. Mead. "Outer-Galaxy molecular clouds." Symposium - International Astronomical Union 106 (1985): 209–10. http://dx.doi.org/10.1017/s0074180900242460.

Full text

Abstract:

Since our original report of CO emission from outside the solar circle in the first quadrant (Kutner and Mead, 1981) we have extended the observations in two ways: (1) We have improved latitude and longitude coverage. Preliminary results on the latitude distribution were reported by Kutner (1983). (2) We have extended our cloud mapping, giving us at least partial CO maps of 55 clouds, along with 13CO, C18O, CO (2–1), and 2-mm H2CO observations of some clouds.

APA, Harvard, Vancouver, ISO, and other styles

12

Johansson, Lars E. B., Arto Heikkilä, and Hans Olofsson. "Molecular Line Observations in the Magellanic Clouds." Symposium - International Astronomical Union 190 (1999): 116–17. http://dx.doi.org/10.1017/s0074180900117553.

Full text

Abstract:

We have observed spectral line emission from a sample of clouds in the Magellanic Clouds to investigate the effects of metallicity and FUV radiation on the physical and chemical properties of the interstellar medium. The clouds were identified by CO surveys and selected to cover a wide range of environments. We present molecular line data for five clouds in the LMC and one cloud in the SMC.

APA, Harvard, Vancouver, ISO, and other styles

13

Rubio, Monica. "Molecular gas in the Small Magellanic Cloud." Symposium - International Astronomical Union 148 (1991): 429–30. http://dx.doi.org/10.1017/s007418090020106x.

Full text

Abstract:

We summarize the results of observations of molecular gas from the Small Magellanic Cloud (SMC) made with low angular resolution (8'.8). These observations show that the CO emission is weak (TA˜ 0.04K) and that the CO luminosities of the Clouds are low compared to those of Galactic molecular clouds. The factor to convert the CO luminosity to molecular hydrogen column density for the SMC is ˜20 and three times larger than those derived for clouds in our Galaxy and in the Large Magellanic Cloud (LMC) respectively. In addition, we present preliminary results of high resolution (40″) observations

APA, Harvard, Vancouver, ISO, and other styles

14

Lazarian, A. "Magnetic Field Generation within Molecular Clouds." Symposium - International Astronomical Union 157 (1993): 429–30. http://dx.doi.org/10.1017/s0074180900174571.

Full text

Abstract:

Magnetic field generation in molecular (atomic) clouds at the early stages of galactic evolution is considered. It is shown that if there is no internal motions immersed the cloud, battery mechanisms (Lazarian 1992a) can account for the generation of thin magnetic shells around clouds insides in plasma with temperature gradients. If turbulent motions are present, the dynamo can be essential. The operation of α — ω, α2 and turbulent dynamos within molecular clouds is discussed. It is shown that the turbulent dynamo leads to generation of magnetic fields in the trace behind the cloud. These magn

APA, Harvard, Vancouver, ISO, and other styles

15

Fujii, Michiko S., and Simon Portegies Zwart. "Formation of young massive clusters from turbulent molecular clouds." Proceedings of the International Astronomical Union 12, S316 (August 2015): 25–30. http://dx.doi.org/10.1017/s1743921316000545.

Full text

Abstract:

AbstractWe simulate the formation and evolution of young star clusters from turbulent molecular clouds using smoothed-particle hydrodynamics and direct N-body methods. We find that the shape of the cluster mass function that originates from an individual molecular cloud is consistent with a Schechter function with power-law slopes of β = −1.73. The superposition of mass functions turn out to have a power-law slope of < −2. The mass of the most massive cluster formed from a single molecular cloud with mass Mg scales with 6.1 M0.51g. The molecular clouds that tend to form massive clusters are

APA, Harvard, Vancouver, ISO, and other styles

16

Alves, João, Marco Lombardi, and Charles Lada. "Insights on molecular cloud structure." Proceedings of the International Astronomical Union 6, S270 (May 2010): 99–102. http://dx.doi.org/10.1017/s1743921311000238.

Full text

Abstract:

AbstractStars form in the densest regions of clouds of cold molecular hydrogen. Measuring structure in these clouds is far from trivial as 99% of the mass of a molecular cloud is inaccessible to direct observation. Over the last decade we have been developing an alternative, more robust density tracer technique based on dust extinction measurements towards background starlight. The new technique does not suffer from the complications plaguing the more conventional molecular line and dust emission techniques, and when used with these can provide unique views on cloud chemistry and dust grain pr

APA, Harvard, Vancouver, ISO, and other styles

17

Yamaguchi, Nobuyuki, Norikazu Mizuno, Hiro Saito, Ken'ichi Matsunaga, Akira Mizuno, Hideo Ogawa, and Yasuo Fukui. "A Study of Dense Molecular Gas and Star Formation toward the Vela Molecular Ridge with NANTEN." Publications of the Astronomical Society of Japan 51, no. 6 (December 1, 1999): 775–90. http://dx.doi.org/10.1093/pasj/51.6.775.

Full text

Abstract:

Abstract New observations of the J=1−0 12CO, 13CO, and C18O emission lines have been extensively made toward the Vela Molecular Ridge (VMR) with NANTEN. The most prominent cloud is the giant molecular cloud, corresponding to the VMR-C region (Vela C). The present C18O distribution has been identified as 29 clouds. Among them, the most massive one is included in Vela C, having a total mass of ∼ 4.4 × 104M⊙. The rest of them are smaller C18O clouds of 102-103M⊙. Star formation in the region is almost exclusively occurring in the C18O clouds. The luminosities of the associated protostellar IRAS s

APA, Harvard, Vancouver, ISO, and other styles

18

Priestley, F. D., and A. P. Whitworth. "Molecular line signatures of cloud–cloud collisions." Monthly Notices of the Royal Astronomical Society 506, no. 1 (June 24, 2021): 775–80. http://dx.doi.org/10.1093/mnras/stab1777.

Full text

Abstract:

ABSTRACT Collisions between interstellar gas clouds are potentially an important mechanism for triggering star formation. This is because they are able to rapidly generate large masses of dense gas. Observationally, cloud collisions are often identified in position–velocity (PV) space through bridging features between intensity peaks, usually of CO emission. Using a combination of hydrodynamical simulations, time-dependent chemistry, and radiative transfer, we produce synthetic molecular line observations of overlapping clouds that are genuinely colliding, and overlapping clouds that are just

APA, Harvard, Vancouver, ISO, and other styles

19

Nogueras-Lara, F., R. Schödel, N. Neumayer, and M. Schultheis. "Distance to three molecular clouds in the central molecular zone." Astronomy & Astrophysics 647 (March 2021): L6. http://dx.doi.org/10.1051/0004-6361/202140554.

Full text

Abstract:

Context. The determination of absolute and relative distances of molecular clouds along the line-of-sight towards the central molecular zone (CMZ) is crucial for inferring its orbital structure and dynamics and for understanding star formation in the clouds. Aims. Recent work has suggested that the G0.253+0.016 cloud (the Brick) does not belong to the CMZ. This motivated us to crosscheck those results, computing the absolute and relative distances to the Brick as well as to another two molecular clouds (the 50 km s−1 and the 20 km s−1 clouds), and discuss their CMZ membership. Methods. We used

APA, Harvard, Vancouver, ISO, and other styles

20

Rosolowsky, E. "Giant Molecular Clouds in M31. I. Molecular Cloud Properties." Astrophysical Journal 654, no. 1 (January 2007): 240–51. http://dx.doi.org/10.1086/509249.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Rubio, Mónica. "Giant Molecular Clouds and Cluster Formation." Symposium - International Astronomical Union 207 (2002): 499–504. http://dx.doi.org/10.1017/s0074180900224303.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

22

Yan, Qing-Zeng, Ji Yang, Yang Su, Yan Sun, Ye Xu, Hongchi Wang, Xin Zhou, and Chen Wang. "Improved Measurements of Molecular Cloud Distances Based on Global Search." Astrophysical Journal 922, no. 1 (November 1, 2021): 8. http://dx.doi.org/10.3847/1538-4357/ac214f.

Full text

Abstract:

Abstract The principle of the background-eliminated extinction-parallax (BEEP) method is examining the extinction difference between on- and off-cloud regions to reveal the extinction jump caused by molecular clouds, thereby revealing the distance in complex dust environments. The BEEP method requires high-quality images of molecular clouds and high-precision stellar parallaxes and extinction data, which can be provided by the Milky Way Imaging Scroll Painting (MWISP) CO survey and the Gaia DR2 catalog, as well as supplementary A V extinction data. In this work, the BEEP method is further impr

APA, Harvard, Vancouver, ISO, and other styles

23

Lehmann, Andrew, and Mark Wardle. "Diffusion of cosmic-ray electrons in the Galactic centre molecular cloud G0.13–0.13." Proceedings of the International Astronomical Union 9, S303 (October 2013): 434–38. http://dx.doi.org/10.1017/s1743921314001082.

Full text

Abstract:

AbstractThe Galactic center (GC) molecular cloud G0.13–0.13 exhibits a shell morphology in CS J = (1 − 0), with ∼ 105 solar masses and expansion speed ∼ 20 km s−1, yielding a total kinetic energy ∼ 1051 erg. Its morphology is also suggestive of an interaction with the nonthermal filaments of the GC arc. 74 MHz emission indicates the presence of a substantial population of low energy electrons permeating the cloud, which could either be produced by the interaction with the arc or accelerated in the shock waves responsible for the cloud's expansion. These scenarios are explored using time depend

APA, Harvard, Vancouver, ISO, and other styles

24

Pound, Marc W., and Alyssa A. Goodman. "The Ursa Major Molecular Clouds." Symposium - International Astronomical Union 170 (1997): 33–35. http://dx.doi.org/10.1017/s0074180900234037.

Full text

Abstract:

The Ursa Major molecular cloud complex lies in the direction of an expanding HI shell known as the North Celestial Pole loop. The NCP loop, which is centered at (l, b) ∼ (138°,30°) and easily seen in IRAS 100 μm emission, is some 60 pc across and 150 pc distant (Meyerdierks et. al 1991). At 100 μm, the Ursa Major clouds appear in projection as “finger” (l ∼ 140, b ∼ 38) which “hangs down” towards the center of the loop and the plane of the Galaxy. Distance estimates to the molecular clouds (Penprase 1993) are consistent with that of the NCP loop, indicating that the clouds are physically assoc

APA, Harvard, Vancouver, ISO, and other styles

25

Sharma, Ekta, Maheswar Gopinathan, Archana Soam, Chang Won Lee, and T. R. Seshadri. "Core orientations and magnetic fields in isolated molecular clouds." Monthly Notices of the Royal Astronomical Society 517, no. 1 (October 11, 2022): 1138–55. http://dx.doi.org/10.1093/mnras/stac2487.

Full text

Abstract:

ABSTRACT Molecular clouds are sites of star formation. Magnetic fields are believed to play an important role in their dynamics and shaping morphology. We aim to study any possible correlation that might exist between the magnetic fields orientation inside the clouds and the magnetic fields at envelope scales and their connection with respect to the observed morphology of the selected clouds. We examine the magnetic field orientation towards the clouds L1512, L1523, L1333, L1521E, L1544, L1517, L1780, and L183, using optical and Planck polarization observations. We also found the correlation b

APA, Harvard, Vancouver, ISO, and other styles

26

Krieger, Nico, Jürgen Ott, Fabian Walter, J. M. Diederik Kruijssen, and Henrik Beuther. "Temperature Evolution of Molecular Clouds in the Central Molecular Zone." Proceedings of the International Astronomical Union 11, S322 (July 2016): 160–61. http://dx.doi.org/10.1017/s1743921316011960.

Full text

Abstract:

AbstractWe infer the absolute time dependence of kinematic gas temperature along a proposed orbit of molecular clouds in the Central Molecular Zone (CMZ) of the Galactic Center (GC). Ammonia gas temperature maps are one of the results of the “Survey of Water and Ammonia in the Galactic Center” (SWAG, PI: J. Ott); the dynamical model of molecular clouds in the CMZ was taken from Kruijssen et al. (2015). We find that gas temperatures increase as a function of time in both regimes before and after the cloud passes pericenter on its orbit in the GC potential. This is consistent with the recent pro

APA, Harvard, Vancouver, ISO, and other styles

27

Braine, J., A. Hughes, E. Rosolowsky, P. Gratier, D. Colombo, S. Meidt, and E. Schinnerer. "Rotation of molecular clouds in M 51." Astronomy & Astrophysics 633 (December 23, 2019): A17. http://dx.doi.org/10.1051/0004-6361/201834613.

Full text

Abstract:

The grand-design spiral galaxy M 51 was observed at 40 pc resolution in CO(1–0) by the PAWS project. A large number of molecular clouds were identified and we search for velocity gradients in two high signal-to-noise subsamples, containing 682 and 376 clouds. The velocity gradients are found to be systematically prograde oriented, as was previously found for the rather flocculent spiral M 33. This strongly supports the idea that the velocity gradients reflect cloud rotation, rather than more random dynamical forces, such as turbulence. Not only are the gradients prograde, but their ∂v/∂x and ∂

APA, Harvard, Vancouver, ISO, and other styles

28

Padoan, Paolo, Tuomas Lunttila, Mika Juvela, Åke Nordlund, David Collins, Alexei Kritsuk, Michael Normal, and Sergey Ustyugov. "Magnetic Fields in Molecular Clouds." Proceedings of the International Astronomical Union 6, S271 (June 2010): 187–96. http://dx.doi.org/10.1017/s1743921311017601.

Full text

Abstract:

AbstractSupersonic magneto-hydrodynamic (MHD) turbulence in molecular clouds (MCs) plays an important role in the process of star formation. The effect of the turbulence on the cloud fragmentation process depends on the magnetic field strength. In this work we discuss the idea that the turbulence is super-Alfvénic, at least with respect to the cloud mean magnetic field. We argue that MCs are likely to be born super-Alfvénic. We then support this scenario based on a recent simulation of the large-scale warm interstellar medium turbulence. Using small-scale isothermal MHD turbulence simulation,

APA, Harvard, Vancouver, ISO, and other styles

29

Knez, C., M. Moore, S. Travis, R. Ferrante, J. Chiar, A. Boogert, L. Mundy, et al. "Comparing ice composition in dark molecular clouds." Proceedings of the International Astronomical Union 4, S251 (February 2008): 47–48. http://dx.doi.org/10.1017/s1743921308021157.

Full text

Abstract:

AbstractWe present 5–20 μm Spitzer/IRS spectroscopy toward stars behind dark molecular clouds. We present preliminary results from the Serpens dark cloud to show the variation between environments within a cloud. We are surveying 3 clouds with varying levels of star formation activity. Serpens has the highest level of activity from our 3 clouds. We show that location as well extinction can cause variations in ice composition. We also find that some lines of sight contain organic molecules such as methane and methanol, and the first detection of acetylene ice in the interstellar medium. We beli

APA, Harvard, Vancouver, ISO, and other styles

30

Henshaw, Jonathan D. "Molecular gas kinematics of the CMZ: Great oaks from little acorns grow." Proceedings of the International Astronomical Union 11, S322 (July 2016): 85–89. http://dx.doi.org/10.1017/s1743921316011972.

Full text

Abstract:

AbstractThe central molecular zone (CMZ) hosts some of the most massive and dense molecular clouds and star clusters in the Galaxy, offering an important window into star formation under extreme conditions. Star formation in this extreme environment may be closely linked to the 3-D distribution and orbital dynamics of the gas. Here I discuss how our new, accurate description of the {l,b,v} structure of the CMZ is helping to constrain its 3-D geometry. I also present the discovery of a highly-regular, corrugated velocity field located just upstream from the dust ridge molecular clouds (which in

APA, Harvard, Vancouver, ISO, and other styles

31

Rosolowsky, Erik, Annie Hughes, Adam K. Leroy, Jiayi Sun, Miguel Querejeta, Andreas Schruba, Antonio Usero, et al. "Giant molecular cloud catalogues for PHANGS-ALMA: methods and initial results." Monthly Notices of the Royal Astronomical Society 502, no. 1 (January 15, 2021): 1218–45. http://dx.doi.org/10.1093/mnras/stab085.

Full text

Abstract:

ABSTRACT We present improved methods for segmenting CO emission from galaxies into individual molecular clouds, providing an update to the cprops algorithms presented by Rosolowsky & Leroy. The new code enables both homogenization of the noise and spatial resolution among data, which allows for rigorous comparative analysis. The code also models the completeness of the data via false source injection and includes an updated segmentation approach to better deal with blended emission. These improved algorithms are implemented in a publicly available Python package, pycprops. We apply these m

APA, Harvard, Vancouver, ISO, and other styles

32

Pudritz, Ralph E. "Formation of structure in star-forming clouds." Canadian Journal of Physics 68, no. 9 (September 1, 1990): 808–23. http://dx.doi.org/10.1139/p90-118.

Full text

Abstract:

Star formation occurs in massive, dense, molecular clouds in the interstellar medium. These clouds have a rich substructure consisting of dense clumps and extended filaments. Since stars only form within these dense clumps, any fundamental theory of star formation must predict their physical properties. This review focusses on the physics of molecular clouds and discusses in this context a particular mechanism for the formation of structure that is well supported by the observations. Strong hydromagnetic waves are likely to be excited in molecular clouds since it is observed that cloud magneti

APA, Harvard, Vancouver, ISO, and other styles

33

Zhang, Miaomiao. "Distances to Nearby Molecular Clouds Traced by Young Stars." Astrophysical Journal Supplement Series 265, no. 2 (April 1, 2023): 59. http://dx.doi.org/10.3847/1538-4365/acc1e8.

Full text

Abstract:

Abstract I present a catalog of distances to 63 molecular clouds located within ∼2.5 kpc of the Sun. The cloud distances are derived based on utilizing the Gaia DR3 parallaxes of the young stellar objects (YSOs). By identifying AllWISE YSO candidates (YSOCs) with infrared excesses and combining them with published YSOC catalogs, I compile an all-sky YSOC sample that is devoid of a significant proportion of contaminants. Using Gaia DR3 astrometric measurements, I associate over 3000 YSOCs with 63 local clouds and obtain the average distance to each cloud by fitting the YSOC parallax distributio

APA, Harvard, Vancouver, ISO, and other styles

34

Tanvir, Tabassum S., and James E. Dale. "Collision between molecular clouds – I. The effect of the cloud virial ratio in head-on collisions." Monthly Notices of the Royal Astronomical Society 494, no. 1 (March 13, 2020): 246–58. http://dx.doi.org/10.1093/mnras/staa665.

Full text

Abstract:

ABSTRACT In a series of papers, we investigate the effect of collisions between turbulent molecular clouds on their structure, evolution, and star formation activity. In this paper, we look into the role of the clouds’ initial virial ratios. Three different scenarios were examined: both clouds initially bound, one cloud bound and one unbound, and both clouds initially unbound. Models in which one or both clouds are bound generate filamentary structures aligned along the collision axis and discernible in position–position and position–velocity space. If neither cloud is bound, no filaments resu

APA, Harvard, Vancouver, ISO, and other styles

35

Inutsuka, Shu-ichiro. "The role of magnetic field in the formation and evolution of filamentary molecular clouds." Proceedings of the International Astronomical Union 14, A30 (August 2018): 100. http://dx.doi.org/10.1017/s1743921319003557.

Full text

Abstract:

AbstractRecent observations have emphasized the importance of the formation and evolution of magnetized filamentary molecular clouds in the process of star formation. Theoretical and observational investigations have provided convincing evidence for the formation of molecular cloud cores by the gravitational fragmentation of filamentary molecular clouds. In this review we summarize our current understanding of various processes that are required in describing the filamentary molecular clouds. Especially we can explain a robust formation mechanism of filamentary molecular clouds in a shock comp

APA, Harvard, Vancouver, ISO, and other styles

36

Zucker, Catherine, Joshua S. Speagle, Edward F. Schlafly, Gregory M. Green, Douglas P. Finkbeiner, Alyssa Goodman, and João Alves. "A compendium of distances to molecular clouds in the Star Formation Handbook." Astronomy & Astrophysics 633 (January 2020): A51. http://dx.doi.org/10.1051/0004-6361/201936145.

Full text

Abstract:

Accurate distances to local molecular clouds are critical for understanding the star and planet formation process, yet distance measurements are often obtained inhomogeneously on a cloud-by-cloud basis. We have recently developed a method that combines stellar photometric data with Gaia DR2 parallax measurements in a Bayesian framework to infer the distances of nearby dust clouds to a typical accuracy of ∼5%. After refining the technique to target lower latitudes and incorporating deep optical data from DECam in the southern Galactic plane, we have derived a catalog of distances to molecular c

APA, Harvard, Vancouver, ISO, and other styles

37

Liu, Lijie, Martin Bureau, Leo Blitz, Timothy A. Davis, Kyoko Onishi, Mark Smith, Eve North, and Satoru Iguchi. "WISDOM Project – IX. Giant molecular clouds in the lenticular galaxy NGC 4429: effects of shear and tidal forces on clouds." Monthly Notices of the Royal Astronomical Society 505, no. 3 (May 27, 2021): 4048–85. http://dx.doi.org/10.1093/mnras/stab1537.

Full text

Abstract:

ABSTRACT We present high spatial resolution (≈12 pc) Atacama Large Millimeter/submillimeter Array 12CO(J = 3–2) observations of the nearby lenticular galaxy NGC 4429. We identify 217 giant molecular clouds within the 450 pc radius molecular gas disc. The clouds generally have smaller sizes and masses but higher surface densities and observed linewidths than those of Milky Way disc clouds. An unusually steep size–linewidth relation ($\sigma \propto R_{\rm c}^{0.8}$) and large cloud internal velocity gradients (0.05–0.91 km s−1 pc−1) and observed virial parameters (〈αobs,vir〉 ≈ 4.0) are found, w

APA, Harvard, Vancouver, ISO, and other styles

38

Shull, Peter, John Dyson, and Franz Kahn. "A Model of SNR Evolution for an O-Star in a Cloudy ISM." International Astronomical Union Colloquium 101 (1988): 231–34. http://dx.doi.org/10.1017/s0252921100102416.

Full text

Abstract:

AbstractWe present an analytical model of SNR evolution in a cloudy interstellar medium for a single progenitor star of spectral type 05 V. The model begins with the progenitor on the zero-age main sequence, includes the effects of the star’s wind and ionizing photons, and ends with the SNR’s assimilation by the ISM. We assume that the ISM consists of atomic clouds, molecular clouds, and a hot intercloud phase. The type of SNR that results bears a strong resemblance to N63A in the Large Magellanic Cloud.

APA, Harvard, Vancouver, ISO, and other styles

39

Koda, Jin, and Jonathan C. Tan. "On the Lifetime of Molecular Clouds with the “Tuning-fork” Analysis." Astrophysical Journal 959, no. 1 (November 28, 2023): 1. http://dx.doi.org/10.3847/1538-4357/ad05c6.

Full text

Abstract:

Abstract The “tuning-fork” (TF) analysis of CO and Hα emission has been used to estimate the lifetimes of molecular clouds in nearby galaxies. With simple model calculations, we show that this analysis does not necessarily estimate cloud lifetimes, but instead captures a duration of the cloud evolutionary cycle, from dormant to star-forming, and then back to a dormant phase. We adopt a hypothetical setup in which molecular clouds (e.g., traced in CO) live forever and form stars (e.g., H ii regions) at some frequency, which then drift away from the clouds. The TF analysis still returns a timesc

APA, Harvard, Vancouver, ISO, and other styles

40

Li, P. S., C. F. McKee, and R. I. Klein. "Structure and Dynamics of Magnetized Dark Molecular Clouds." Proceedings of the International Astronomical Union 10, H16 (August 2012): 386. http://dx.doi.org/10.1017/s1743921314011557.

Full text

Abstract:

Massive infrared dark clouds (IRDCs) are believed to be the precursors to star clusters and massive stars (e.g. Bergin & Tafalla 2007). The supersonic, turbulent nature of molecular clouds in the presence of magnetic fields poses a great challenge in understanding the structure and dynamics of magnetized molecular clouds and the star formation therein. Using the high-order radiation-magneto-hydrodynamic adaptive mesh refinement (AMR) code ORION2 (Li et al. 2012), we perform a large-scale driven-turbulence simulation to reveal the 3D filamentary structure and dynamical state of a highly sup

APA, Harvard, Vancouver, ISO, and other styles

41

Koda, Jin, Linda Watson, Françoise Combes, Monica Rubio, Samuel Boissier, Masafumi Yagi, David Thilker, et al. "First Detection of the Molecular Cloud Population in the Extended Ultraviolet Disk of M83." Astrophysical Journal 941, no. 1 (December 1, 2022): 3. http://dx.doi.org/10.3847/1538-4357/ac9dfc.

Full text

Abstract:

Abstract We report a CO(J = 3−2) detection of 23 molecular clouds in the extended ultraviolet (XUV) disk of the spiral galaxy M83 with the Atacama Large Millimeter/submillimeter Array. The observed 1 kpc2 region is at about 1.24 times the optical radius (R 25) of the disk, where CO(J = 2–1) was previously not detected. The detection and nondetection, as well as the level of star formation (SF) activity in the region, can be explained consistently if the clouds have the mass distribution common among Galactic clouds, such as Orion A—with star-forming dense clumps embedded in thick layers of bul

APA, Harvard, Vancouver, ISO, and other styles

42

Dessauges-Zavadsky, Miroslava, Johan Richard, Françoise Combes, Daniel Schaerer, Wiphu Rujopakarn, and Lucio Mayer. "Molecular clouds in a Milky Way progenitor at z = 1." Proceedings of the International Astronomical Union 15, S352 (June 2019): 269–73. http://dx.doi.org/10.1017/s1743921319008949.

Full text

Abstract:

AbstractThanks to the remarkable ALMA capabilities and the unique configuration of the Cosmic Snake galaxy behind a massive galaxy cluster, we could resolve molecular clouds down to 30 pc linear physical scales in a typical Milky Way progenitor at z = 1.036, through CO(4–3) observations performed at the ∼ 0.2″ angular resolution. We identified 17 individual giant molecular clouds. These high-redshift molecular clouds are clearly different from their local analogues, with 10–100 times higher masses, densities, and internal turbulence. They are offset from the Larson scaling relations. We argue

APA, Harvard, Vancouver, ISO, and other styles

43

Mullens, Elijah, Catherine Zucker, Claire E. Murray, and Rowan Smith. "Characterizing the 3D Structure of Molecular Cloud Envelopes in the Cloud Factory Simulations." Astrophysical Journal 966, no. 1 (May 1, 2024): 127. http://dx.doi.org/10.3847/1538-4357/ad306a.

Full text

Abstract:

Abstract We leverage recent numerical simulations of highly resolved star-forming regions in a Milky Way–like galaxy to explore the nature of extended gaseous envelopes around molecular clouds. We extract a sample of two dozen star-forming clouds from the feedback-dominated suite of Cloud Factory simulations. With the goal of exploring the 3D thermal and chemical structure of the gas, we measure and fit the clouds’ radial profiles with multiple tracers, including n H I , n H 2 , n H tot , n CO, and gas temperature. We find that while solar neighborhood clouds recently detected via 3D dust mapp

APA, Harvard, Vancouver, ISO, and other styles

44

Jaffe, D. T. "Warm Molecular Clouds." Symposium - International Astronomical Union 150 (1992): 311–15. http://dx.doi.org/10.1017/s0074180900090239.

Full text

Abstract:

Warm molecular gas is important in a large range of astronomical contexts. We discuss here determinations of the temperature and mass of warm material in protostellar disks and cores, photon dominated regions, and molecular material shocked by protostellar outflows. We then compare these results to heating and cooling models. The models of dense cores and photon dominated regions are not adequate to explain the large amounts of warm material observed. This conclusion raises the possibility that there may be other heating mechanisms at work in these regions which theorists have not yet included

APA, Harvard, Vancouver, ISO, and other styles

45

BALLY, J. "Interstellar Molecular Clouds." Science 232, no. 4747 (April 11, 1986): 185–93. http://dx.doi.org/10.1126/science.232.4747.185.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Li, Hua-Bai. "Magnetic Fields in Molecular Clouds—Observation and Interpretation." Galaxies 9, no. 2 (June 8, 2021): 41. http://dx.doi.org/10.3390/galaxies9020041.

Full text

Abstract:

The Zeeman effect and dust grain alignment are two major methods for probing magnetic fields (B-fields) in molecular clouds, largely motivated by the study of star formation, as the B-field may regulate gravitational contraction and channel turbulence velocity. This review summarizes our observations of B-fields over the past decade, along with our interpretation. Galactic B-fields anchor molecular clouds down to cloud cores with scales around 0.1 pc and densities of 104–5 H2/cc. Within the cores, turbulence can be slightly super-Alfvénic, while the bulk volumes of parental clouds are sub-Alfv

APA, Harvard, Vancouver, ISO, and other styles

47

Niwa, Takahiro, Yoichi Itoh, Kengo Tachihara, Yumiko Oasa, Kazuyoshi Sunada, and Koji Sugitani. "Radio observation of molecular clouds around the W5-East triggered star-forming region." Proceedings of the International Astronomical Union 2, S237 (August 2006): 454. http://dx.doi.org/10.1017/s1743921307002426.

Full text

Abstract:

It is known that most of stars are formed as clusters (Lada & Lada 2003, ARAA 41, L57) and clusters are formed by triggering. However, the relationships of molecular clouds' conditions and properties of formed stars by triggering is not well studied. To clarify differences between triggered and spontaneous star formation through physical properties of molecular clouds (e.g. mass, density, morphology), we observed the W5-East HII region. The W5-East HII region is located at 2 kpc and has a 10 pc extent of HII region. This region has 3 Bright Rimmed Clouds (BRCs; Sugitani et al. 1991, ApJS 7

APA, Harvard, Vancouver, ISO, and other styles

48

Yuan, Lixia, Ji Yang, Fujun Du, Xunchuan Liu, Yang Su, Qing-Zeng Yan, Xuepeng Chen, et al. "On the Spatial Distribution of ¹³CO Structures within ¹²CO Molecular Clouds." Astrophysical Journal 944, no. 1 (February 1, 2023): 91. http://dx.doi.org/10.3847/1538-4357/acac26.

Full text

Abstract:

Abstract We look into the 2851 12CO molecular clouds harboring 13CO structures to reveal the distribution of the projected angular separations and radial velocity separations between their internal 13CO structures. The projected angular separations are determined using the minimal spanning tree algorithm. We find that ∼50% of the angular separations fall in a narrow range of ∼3′–7′ with a median of ∼5′, and the corresponding radial velocity separations mainly range from ∼0.3 to 2.5 km s−1. The mean and standard deviation of the angular separations of the internal 13CO structures within 12CO cl

APA, Harvard, Vancouver, ISO, and other styles

49

Yan, Qing-Zeng, Bo Zhang, Ye Xu, Sufen Guo, Jean-Pierre Macquart, Zheng-Hong Tang, and Andrew John Walsh. "Distances to molecular clouds at high galactic latitudes based on Gaia DR2." Astronomy & Astrophysics 624 (March 29, 2019): A6. http://dx.doi.org/10.1051/0004-6361/201834337.

Full text

Abstract:

We report the distances of molecular clouds at high Galactic latitudes (|b| > 10°) derived from parallax and G-band extinction (AG) measurements in the second Gaia data release, Gaia DR2. Aided by Bayesian analyses, we determined distances by identifying the breakpoint in the extinction AG toward molecular clouds and using the extinction AG of Gaia stars around molecular clouds to confirm the breakpoint. We used nearby star-forming regions, such as Orion, Taurus, Cepheus, and Perseus, whose distances are well known to examine the reliability of our method. By comparing with previous results

APA, Harvard, Vancouver, ISO, and other styles

50

Genzel, R., G. J. Stacey, C. H. Townes, A. Poglitsch та N. Geis. "158μm [CII] Mapping of the Galactic Center Molecular Clouds". Symposium - International Astronomical Union 136 (1989): 151–55. http://dx.doi.org/10.1017/s0074180900186450.

Full text

Abstract:

We have made 55″ resolution maps of the 158 μm [CII] emission line in the region of the curved, thermal filaments and the +20 / +50 kms−1 molecular clouds in Sgr A. The [CII] emission is spatially well correlated with the radio continuum in the filaments. The large intensity of the [CII] radiation excludes shocks as the origin of the ionization and we conclude that the curved filaments are most likely photo-ionized HII regions at the surface of dense molecular clouds. Our [CII] maps of the +20 / +50 kms−1 clouds indicate that the +50 kms−1 cloud is close to (<10pc) Sgr A west while the more

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!