scholarly journals Molecular Line Studies of Dense Core Motions

1992 ◽  
Vol 150 ◽  
pp. 217-222
Author(s):  
Yuefang Wu
Keyword(s):  
Line Width ◽  
Dense Core ◽  
Emission Region ◽  
Molecular Line ◽  
Dense Cores ◽  
Chemical Effects ◽  
Size Relationship ◽  
Molecular Lines ◽  
Line Widths

Molecular lines have revealed various supporting motions in dense cores. Line widths and emission region sizes of NH3 and CS in the same kind of cores or of the same line in cores with or without sources are different and can not be explained with the line width- size relationship. Outflows in dense cores show rich characteristics which can account for the NH3 emission difference between the two kinds of the cores; CS emission is consistent with the chemical effects in shocked regions. Rotation exists in both kinds of cores and may be related to the observed polarities and collimations of outflows.

scholarly journals Molecular Line Emission from the Young Planetary Nebula NGC 7027

2003 ◽  
Vol 209 ◽  
pp. 272-272
Author(s):  
Tatsuhiko I. Hasegawa ◽  
Sun Kwok
Keyword(s):  
Planetary Nebula ◽  
Small Volume ◽  
Line Emission ◽  
Peak Level ◽  
Ionization Front ◽  
Emission Region ◽  
Molecular Line ◽  
Ngc 7027 ◽  
Line Widths ◽  
Co Emission

NGC 7027 has been observed in eleven molecular species (in seventeen transitions) in the 200 and 300 GHz bands with the James Clarke Maxwell Telescope (Hasegawa & Kwok 2001). The results include a first detection of C2H in this source. The observed spectra of HCO+, H13CO+, HCN, CN, C2H, and CO+ show line widths larger than that of bulk CO emission but coincident with the full width at detection limit of weak wings in CO spectra. The sizes of the HCO+, HCN, and CN emitting regions are 13″ in diameter at half-peak level, significantly smaller than that (60″) of the CO emitting region. The emission of all the observed molecules other than CO and 13CO must originate from a very small volume compared with the entire CO envelope of NGC 7027. Since the central 10″ region is an ionized region, the molecular emission region (except CO) must be geometrically thin (ΔR = 1″ – 2″) and must be close to the ionization front.

scholarly journals Interaction between molecular outflows and dense gas in the cluster-forming region OMC-2/FIR4

2006 ◽  
Vol 2 (S237) ◽  
pp. 475-475
Author(s):  
Yoshito Shimajiri ◽  
S. Takahashi ◽  
S. Takakuwa ◽  
M. Saito ◽  
R. Kawabe
Keyword(s):  
Cluster Formation ◽  
Major Axis ◽  
List Type ◽  
Dense Gas ◽  
Continuum Source ◽  
Molecular Outflows ◽  
Molecular Outflow ◽  
Dense Cores ◽  
Potential Source ◽  
Molecular Lines

AbstractSince most stars are born as members of clusters (Lada & Lada 2003), it is important to clarified the detailed mechanism of cluster formation for comprehensive understanding of star formation. However, our current understanding of cluster formation is limited due to the followings; (a)Cluster forming regions are located at the far distance.(b)There are complex mixtures of outflows and dense gas in cluster forming regions. So, we focused on the Orion Molecular Cloud 2 region (OMC-2), a famous cluster-forming region (Lada & Lada 2003) and the most nearest GMC. We observed the FIR 4 region with the Nobeyama Millimeter Array(NMA), Atacama Submillimeter Telescope Experiment (ASTE). In this region, there are 3 protostars (FIR3, FIR4, FIR5) which were identified as 1.3 mm dust continuum sources (Chini et al. 1997) and driving sources of mixed outflows, and FIR 4 is the most strongest source of 1.3 mm dust continuum in OMC-2. Molecular lines we adopted are a high density (105cm−3) gas tracer of H13CO+ (J=1-0), a molecular outflow tracer of 12CO(J=1-0) and 12CO(J=3-2), and SiO(J=2-1 v=0) as a tracer of shocks associated with an interaction between outflows and dense gas.From results of the 12CO(J=1-0) outflow, H13CO+ dense gas, and the SiO shock, the outflow from FIR 3 interacts with dense gas in the FIR 4 region. Moreover the Position-Velocity diagram along the major axis of the 12CO(J=3-2) outflow shows that the 12CO(J=1-0) and SiO emission exhibits a L shape (the line widths increase in the interacting region in morphology). This is an evidence of interaction between the outflows and dense gas (Takakuwa et al. 2003). From result of the 3 mm dust continuum, the interacted region by the molecular outflow of FIR 3 is an assemble of seven dense cores. The mass of each core is 0.1-0.8 M. This clumpy structure is evident only at FIR 4 in the entire OMC-2/3 region. There are possible that two cores are in the proto-stellar phase, because 3 mm dust continuum source correspond to NIR source or 3.6 cm f-f jet source. From these results, cores in the FIR 4 region may be potential source of the next-generation stars. In the other words, there is a possibility that the molecular outflow ejected from FIR 3 is triggering the cluster formation in the FIR 4 region.

scholarly journals Temporal and Spatial Fluctuations in Widths of solar Euv Lines

1980 ◽  
Vol 51 ◽  
pp. 53-53
Author(s):  
R.G. Athay ◽  
O.R. White
Keyword(s):  
Line Width ◽  
Sound Speed ◽  
Large Scale ◽  
Small Cells ◽  
The Sun ◽  
Doppler Shifts ◽  
Spatial Fluctuations ◽  
Local Sound ◽  
Line Widths ◽  
Temporal And Spatial

AbstractAnalyses of some 300 hours of time sequences of solar EUV line profiles obtained with 0S0-8 show large fluctuations in line widths. At a given location on the sun, line widths fluctuate temporally on time scales ranging from less than a minute to over an hour. At any given time, line widths fluctuate spatially on a variety of scales ranging from active region size to arc second size. Temporal and spatial fluctuations are of approximately the same amplitude. Thus, the sun can be characterized by an aggregate of small cells in each of which line widths are fluctuating in time and which have random phases with respect to each other.Spatial fluctuations in line width are correlated with large scale spatial fluctuations in brightness for some lines but not for others. Temporal fluctuations in width are sometimes correlated with either Doppler shifts or intensity fluctuations, but more often such correlations are absent.For a given line, the line width varies through an extreme range of about a factor of two. Nonthermal components of line width vary from approximately the local sound speed to a small fraction of the sound speed.

scholarly journals Dense core structure and fragmentation in the Rho Ophiuchi molecular cloud

1991 ◽  
Vol 147 ◽  
pp. 229-233
Author(s):  
Alwyn Wootten
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Molecular Cloud ◽  
Surface Density ◽  
Core Structure ◽  
Dense Core ◽  
Dense Cores ◽  
Rho Ophiuchi ◽  
Very High ◽  
Taurus Molecular Cloud

About a dozen distinct dense cores have been identified in the Rho Ophiuchi molecular cloud. The properties of these cores are summarized and compared to the properties of cores in the Taurus molecular cloud, a less efficient region of star formation, and in DR21(OH), a more massive region of star formation. The data are consistent with a picture in which more massive clouds have a higher surface density of cores, which in turn are more massive. The adjacent cores in L1689N have been studied with very high resolution; one has formed stars and one never has. The structure of these cores shows a tendency for duplicity of structures from the largest scales (1 pc) to the smallest (50 AU).

scholarly journals Massive Star Formation in W49

1987 ◽  
Vol 115 ◽  
pp. 143-145
Author(s):  
J. Dreher ◽  
S. Vogel ◽  
S. Terebey ◽  
W. J. Welch
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Massive Star ◽  
Hii Regions ◽  
Molecular Line ◽  
The Galaxy ◽  
Molecular Lines ◽  
H Ii Region ◽  
Scale Structures ◽  
The Continuum

W49 is the most luminous H II region complex in the galaxy. VLA maps in the continuum reveal a complex of more than two dozen compact HII regions, including a ring-like distribution of a dozen such regions within a volume of 1 pc. In addition to the VLA maps, we have obtained high resolution maps in this field with the Hat Creek Millimeter Interferometer in the following molecular lines: HCO+(1-0), H13CO+(1-0), SiO(v = 0, J = 2-1), SiO(v = 1, J = 2-1), H13CN(1-0), HC15N(1-0), SO2 [8(3,5)-9(2,8)], SO2[8(1,7)-8(0,8)], SO[2(2)-1(1)], and CH3CH2CN[10(1,10)-9(1,9)], all near 3 mm wavelengh. These maps will be discussed. The HCO+distribution corresponds to the larger scale structures observed in the continuum maps. In contrast the SO and SiO sources are quite compact. Using the detailed molecular line results obtained in the ORION/KL region as a guide, we are able to identify these latter sources as regions in which the star formation is at an earlier stage, regions where there are outflows.

Implementation of Wider Lane Lines to Improve Sight Distance from Opposing Left-Turn Lanes

2000 ◽  
Vol 1708 (1) ◽  
pp. 12-19
Author(s):  
Patrick S. Byrd ◽  
Patrick T. McCoy ◽  
Geza Pesti ◽  
Virendra A. Singh
Keyword(s):  
Regression Analysis ◽  
Line Width ◽  
Left Turn ◽  
Sight Distance ◽  
Before And After ◽  
Lane Line ◽  
Line Widths

Vehicles turning left at intersections from opposing left-turn lanes often restrict each other’s sight distance. Previous research has developed guidelines for offsetting opposing left-turn lanes to provide adequate sight distances. Implementation of these guidelines at existing intersections typically involves reconstructing the left-turn lanes. However, the results of the before-and-after studies presented demonstrate that increasing the width of the lane lines between left-turn lanes and the adjacent through lanes also can be used as a means of improving the sight distance between opposing left-turn lanes. Regression analysis was used to determine a relationship between lane-line width and available sight distance that can be used to design lane-line widths that provide the required sight distance for opposing left-turn vehicles.

Geometrical effects and disintegration of narrow TiSi2/poly-Si lines

1990 ◽  
Vol 181 ◽  
Author(s):  
H. Norström ◽  
K. Maex ◽  
P. Vandenabeele
Keyword(s):  
Thermal Stability ◽  
Line Width ◽  
Side Wall ◽  
Geometrical Shape ◽  
Cross Sectional ◽  
Line Widths ◽  
Geometrical Effects ◽  
Thermal Stability Of

ABSTRACTThe geometrical shape and the thermal stability of the TiSi2/poly-Si interface on narrow lines has been studied. The examined line-widths varied between 0.8 μm and 1.5 μm. The thermal stability was found to strongly correlate to the actual line-width of the structures. At the onset of degradation, at and above 900°C, narrow lines were observed to disintegrate at a much faster rate than wider ones. Cross-sectional microscopy (TEM and SEM) revealed the TiSi2/poly-Si interface to be curved inwards. The interface bowing was found to be more pronounced on narrow lines. It is suggested that the interface bowing results from a mechanical pinning of the TiSi2/poly-Si interface by the side-wall spacers.

scholarly journals The Nature of the Dense Core Population in the Pipe Nebula: A Survey of NH 3 , CCS, and HC 5 N Molecular Line Emission

2008 ◽  
Vol 174 (2) ◽  
pp. 396-425 ◽  
Author(s):  
J. M. Rathborne ◽  
C. J. Lada ◽  
A. A. Muench ◽  
J. F. Alves ◽  
M. Lombardi
Keyword(s):  
Line Emission ◽  
Dense Core ◽  
Molecular Line

Line-Width Dependence of Void Formation in Ti-Salicided BF2-Doped Polysilicon Lines

1999 ◽  
Vol 564 ◽  
Author(s):  
H. N. Chua ◽  
K. L. Pey ◽  
S. Y. Siah ◽  
E. H. Lim ◽  
C. S. Ho
Keyword(s):  
Line Width ◽  
Void Formation ◽  
Size Increase ◽  
Concentration Profiles ◽  
Line Widths ◽  
Depth Concentration

AbstractWe report the first observation of voids in sub-quarter micron Ti-salicided BF2-dopedpolycrystalline silicon (polySi) lines. Some of the voids, with sizes ranging from 10 to 100nm, can be clearly seen on the surface of the TiSi2 film whereas others are situated below the TiSi2 surface. The void density and size increase with decreasing polySi line-width, especially for line-widths < 0.24 µm. The voiding phenomenon was also observed to be moresevere for TiSi2 fabricated with enhanced salicidation techniques such as pre-amorphization-implant(PAl) and implant-through-metal (ITM) as compared to the conventional salicidationmethod without amorphization. The origin of the voids is found to coincide with the fluorinepeak at the TiSi2/polySi interface in the SIMS depth-concentration profiles.

scholarly journals Probing the black hole - bulge relationship at high redshift with CO molecular lines

2012 ◽  
Vol 8 (S292) ◽  
pp. 196-196
Author(s):  
Xue-Bing Wu
Keyword(s):  
Black Hole ◽  
Line Width ◽  
Velocity Dispersion ◽  
High Redshift ◽  
Seyfert Galaxies ◽  
Additional Parameter ◽  
Host Galaxies ◽  
Inclination Angles ◽  
Molecular Lines ◽  
Tight Correlation

AbstractIt has been suggested that the CO line width (FWHM(CO)) is a surrogate for the bulge velocity dispersion (σ) of the host galaxies of high-redshift quasars, and the black hole – bulge (M−σ) relation obtained with this assumption departs significantly from the M−σ relation in the local universe. Based on an investigation of the correlation between the CO line width and the bulge velocity dispersion using a sample of 33 nearby Seyfert galaxies, we find that the formula adopted in previous studies, σ=FWHM(CO)/2.35, is generally not a good approximation. By involving the galactic inclination angle i as an additional parameter, we obtain a tight correlation between the inclination-corrected CO line width and the bulge velocity dispersion, namely, FWHM(CO)/sin i=−67.16±80.18+(3.62±0.68)σ. Using this new relation, we can better estimate the bulge velocity dispersion from the CO line width if the galactic inclination is known. We apply this new relation to nine high-redshift quasars with CO line detections and find that they are consistent with the local M−σ relation if their inclination angles are around 15°. The possible smaller inclinations of the high-redshift quasars are preferred because of their relatively greater likelihood of detection, and are also consistent with their relatively smaller CO line widths compared to the submillimeter galaxies (SMGs) at high redshift having a similar total amount of molecular gas.

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