scholarly journals The ALMA-PILS survey: gas dynamics in IRAS 16293−2422 and the connection between its two protostars

2019 ◽  
Vol 626 ◽  
pp. A93 ◽  
Author(s):  
M. H. D. van der Wiel ◽  
S. K. Jacobsen ◽  
J. K. Jørgensen ◽  
T. L. Bourke ◽  
L. E. Kristensen ◽  
...  
Keyword(s):  
Gas Dynamics ◽  
Angular Resolution ◽  
Spatial Scales ◽  
Morphological Structure ◽  
Molecular Gas ◽  
Evolutionary Stage ◽  
Data Set ◽  
Envelope Material ◽  
Molecular Lines ◽  
Structure Lead

Context. The majority of stars form in binary or higher order systems. The evolution of each protostar in a multiple system may start at different times and may progress differently. The Class 0 protostellar system IRAS 16293–2422 contains two protostars, “A” and “B”, separated by ~600 au and embedded in a single, 104 au scale envelope. Their relative evolutionary stages have been debated. Aims. We aim to study the relation and interplay between the two protostars A and B at spatial scales of 60 au up to ~103 au. Methods. We selected molecular gas line transitions of the species CO, H2CO, HCN, CS, SiO, and C2H from the ALMA-PILS spectral imaging survey (329–363 GHz) and used them as tracers of kinematics, density, and temperature in the IRAS 16293–2422 system. The angular resolution of the PILS data set allows us to study these quantities at a resolution of 0.5′′ (60 au at the distance of the source). Results. Line-of-sight velocity maps of both optically thick and optically thin molecular lines reveal: (i) new manifestations of previously known outflows emanating from protostar A; (ii) a kinematically quiescent bridge of dust and gas spanning between the two protostars, with an inferred density between 4 × 104 cm−3 and ~3 × 107 cm−3; and (iii) a separate, straight filament seemingly connected to protostar B seen only in C2H, with a flat kinematic signature. Signs of various outflows, all emanating from source A, are evidence of high-density and warmer gas; none of them coincide spatially and kinematically with the bridge. Conclusions. We hypothesize that the bridge arc is a remnant of filamentary substructure in the protostellar envelope material from which protostellar sources A and B have formed. One particular morphological structure appears to be due to outflowing gas impacting the quiescent bridge material. The continuing lack of clear outflow signatures unambiguously associated to protostar B and the vertically extended shape derived for its disk-like structure lead us to conclude that source B may be in an earlier evolutionary stage than source A.

scholarly journals Molecular gas dynamics in the Rosette Nebula

2008 ◽  
Vol 4 (S251) ◽  
pp. 125-126
Author(s):  
Henry E. Matthews ◽  
William R. F. Dent
Keyword(s):  
Velocity Gradient ◽  
Gas Dynamics ◽  
Angular Resolution ◽  
Molecular Gas ◽  
Rosette Nebula ◽  
A Chain

AbstractWe present observations of the Rosette Nebula and its near environment in the CO 3–2 transition obtained with an angular resolution of 20″. The gas dynamics of the region are complex; we find (1) a ring of gas expanding at about 20 km s−1, (2) a number of collimated outflow sources, and (3) a chain of dust clumps having a velocity gradient along its length.

scholarly journals SuperMALT: Physical and Chemical Properties of Massive and Dense Clumps

2017 ◽  
Vol 13 (S332) ◽  
pp. 254-260
Author(s):  
Sudeep Neupane ◽  
Guido Garay ◽  
Yanett Contreras ◽  
Keyword(s):  
Angular Resolution ◽  
Chemical Properties ◽  
Evolutionary Stage ◽  
Physical And Chemical Properties ◽  
Line Profiles ◽  
High Excitation ◽  
Physical Chemical ◽  
Molecular Lines ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractThe SuperMALT survey is observing 76 MALT90 clumps at different evolutionary stages (from pre-stellar or quiescent to HII) in high excitation molecular lines and key isotopomers using the Apex 12m telescope with an angular resolution of ∼20” and a velocity resolution of ∼0.1 km/s. The aim of this survey is to determine the physical, chemical, and kinematical properties of the gas within clumps as they evolve. Here we report some preliminary results based on observations of the J=3-2 & 4-3 lines of HNC, HCN, HCO+, N2H+ and of the J=3-2 line of the isotopologue H13CO+. We find that the morphologies and line profiles vary with the evolutionary stage of the clumps. The average line width increases from quiescent to HII clumps while line ratios show hint of chemical differences among the various evolutionary stages.

scholarly journals M 31's Molecular Arms at All Scales to Below 10 pc

2001 ◽  
Vol 205 ◽  
pp. 352-355 ◽  
Author(s):  
N. Neininger ◽  
Ch. Nieten ◽  
M. Guélin ◽  
H. Ungerechts ◽  
R. Lucas ◽  
...  
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
Molecular Gas ◽  
Data Set ◽  
Unique Data ◽  
Small Scales ◽  
M 31 ◽  
Star Formation Regions ◽  
The Individual ◽  
First Time

I present a unique data set for the study of molecular gas in galaxies: a complete, high-resolution survey of the CO in M 31 and additional local studies. The fully sampled survey has an angular resolution of 23 FWHM and the interferometric data attain the pc-scale with sub-arcsecond resolution. For the first time it is now possible to study large and small scales in conjunction. Thus we are able to derive the global structure and study the links down to the individual cloud complexes and star formation regions.

From global to local scales in galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 391-395
Author(s):  
Sebastian F. Sánchez ◽  
Carlos Lopez Cobá
Keyword(s):  
Star Formation ◽  
Spatial Scales ◽  
Bimodal Distribution ◽  
Spectroscopic Properties ◽  
Molecular Gas ◽  
Ionized Gas ◽  
Galaxy Surveys ◽  
Quenching Process ◽  
Formation Efficiency ◽  
Integral Field

AbstractWe summarize here some of the results reviewed recently by Sanchez (2020) comprising the advances in the comprehension of galaxies in the nearby universe based on integral field spectroscopic galaxy surveys. In particular we explore the bimodal distribution of galaxies in terms of the properties of their ionized gas, showing the connection between the star-formation (quenching) process with the presence (absence) of molecular gas and the star-formation efficiency. We show two galaxy examples that illustrates the well known fact that ionization in galaxies (and the processes that produce it), does not happen monolitically at galactic scales. This highlight the importance to explore the spectroscopic properties of galaxies and the evolutionary processes unveiled by them at different spatial scales, from sub-kpc to galaxy wide.

scholarly journals Resolving ice cloud optical thickness biases between CALIOP and MODIS using infrared retrievals

2016 ◽  
Vol 16 (8) ◽  
pp. 5075-5090 ◽  
Author(s):  
Robert E. Holz ◽  
Steven Platnick ◽  
Kerry Meyer ◽  
Mark Vaughan ◽  
Andrew Heidinger ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Spatial Scales ◽  
Radiative Properties ◽  
Radiation Balance ◽  
Data Set ◽  
Mean Values ◽  
Ice Cloud ◽  
Lidar Ratio ◽  
Cloud Optical Thickness ◽  
The Impact

Abstract. Despite its importance as one of the key radiative properties that determines the impact of upper tropospheric clouds on the radiation balance, ice cloud optical thickness (IOT) has proven to be one of the more challenging properties to retrieve from space-based remote sensing measurements. In particular, optically thin upper tropospheric ice clouds (cirrus) have been especially challenging due to their tenuous nature, extensive spatial scales, and complex particle shapes and light-scattering characteristics. The lack of independent validation motivates the investigation presented in this paper, wherein systematic biases between MODIS Collection 5 (C5) and CALIOP Version 3 (V3) unconstrained retrievals of tenuous IOT (< 3) are examined using a month of collocated A-Train observations. An initial comparison revealed a factor of 2 bias between the MODIS and CALIOP IOT retrievals. This bias is investigated using an infrared (IR) radiative closure approach that compares both products with MODIS IR cirrus retrievals developed for this assessment. The analysis finds that both the MODIS C5 and the unconstrained CALIOP V3 retrievals are biased (high and low, respectively) relative to the IR IOT retrievals. Based on this finding, the MODIS and CALIOP algorithms are investigated with the goal of explaining and minimizing the biases relative to the IR. For MODIS we find that the assumed ice single-scattering properties used for the C5 retrievals are not consistent with the mean IR COT distribution. The C5 ice scattering database results in the asymmetry parameter (g) varying as a function of effective radius with mean values that are too large. The MODIS retrievals have been brought into agreement with the IR by adopting a new ice scattering model for Collection 6 (C6) consisting of a modified gamma distribution comprised of a single habit (severely roughened aggregated columns); the C6 ice cloud optical property models have a constant g ≈ 0.75 in the mid-visible spectrum, 5–15 % smaller than C5. For CALIOP, the assumed lidar ratio for unconstrained retrievals is fixed at 25 sr for the V3 data products. This value is found to be inconsistent with the constrained (predominantly nighttime) CALIOP retrievals. An experimental data set was produced using a modified lidar ratio of 32 sr for the unconstrained retrievals (an increase of 28 %), selected to provide consistency with the constrained V3 results. These modifications greatly improve the agreement with the IR and provide consistency between the MODIS and CALIOP products. Based on these results the recently released MODIS C6 optical products use the single-habit distribution given above, while the upcoming CALIOP V4 unconstrained algorithm will use higher lidar ratios for unconstrained retrievals.

The use of wavelet transforms for improved interpretation of airborne transient electromagnetic data

Geophysics ◽  
2013 ◽  
Vol 78 (3) ◽  
pp. E117-E123 ◽  
Author(s):  
Vanessa Nenna ◽  
Adam Pidlisecky
Keyword(s):  
Wavelet Transforms ◽  
Oil And Gas ◽  
Spatial Scales ◽  
Data Sets ◽  
Data Set ◽  
Topographic Features ◽  
Transient Electromagnetic ◽  
Power Maps ◽  
Southern Alberta ◽  
Cultural Noise

The continuous wavelet transform (CWT) is used to create maps of dominant spatial scales in airborne transient electromagnetic (ATEM) data sets to identify cultural noise and topographic features. The introduced approach is applied directly to ATEM data, and does not require the measurements be inverted, though it can easily be applied to an inverted model. For this survey, we apply the CWT spatially to B-field and dB/dt ATEM data collected in the Edmonton-Calgary Corridor of southern Alberta. The average wavelet power is binned over four ranges of spatial scale and converted to 2D maps of normalized power within each bin. The analysis of approximately 2 million soundings that make up the survey can be run on the order of minutes on a 2.4 GHz Intel processor. We perform the same CWT analysis on maps of surface and bedrock topography and also compare ATEM results to maps of infrastructure in the region. We find that linear features identified on power maps that differ significantly between B-field and dB/dt data are well correlated with a high density of infrastructure. Features that are well correlated with topography tend to be consistent in power maps for both types of data. For this data set, use of the CWT reveals that topographic features and cultural noise from high-pressure oil and gas pipelines affect a significant portion of the survey region. The identification of cultural noise and surface features in the raw ATEM data through CWT analysis provides a means of focusing and speeding processing prior to inversion, though the magnitude of this affect on ATEM signals is not assessed.

Black hole mass measurement in nearby galaxy using molecular gas dynamics

2016 ◽  
Author(s):  
Kyoko Onishi ◽  
Satoru Iguchi ◽  
Timothy Davis ◽  
Martin Bureau ◽  
Michele Cappellari ◽  
...  
Keyword(s):  
Black Hole ◽  
Gas Dynamics ◽  
Mass Measurement ◽  
Molecular Gas ◽  
Nearby Galaxy ◽  
Black Hole Mass

scholarly journals The Molecular Outflow and CO Bullets in HH111

1997 ◽  
Vol 182 ◽  
pp. 141-152 ◽  
Author(s):  
J. Cernicharo ◽  
R. Neri ◽  
Bo Reipurth
Keyword(s):  
High Velocity ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Low Velocity ◽  
Molecular Outflow ◽  
Hh Objects ◽  
Physical Phenomena ◽  
First Time

We present high angular resolution observations of the molecular outflow associated with the optical jet and HH objects of the HH111 system. Interferometric observations in the CO J =2–1 and J =1–0 lines of the high velocity bullets associated with HH111 are presented for the first time. The molecular gas in these high velocity clumps has a moderate kinetic temperature and a mass of a few 10–4 M⊙ per bullet. We favor the view that HH jets and CO bullets, which represent different manifestations of the same physical phenomena, are driving the low-velocity molecular outflow.

scholarly journals 12C18O in OMC-1: Kinematics, Molecular Column Density, and Kinetic Temperature Distribution

1987 ◽  
Vol 115 ◽  
pp. 145-146
Author(s):  
T. L. Wilson ◽  
E. Serabyn ◽  
C. Henkel ◽  
C. M. Walmsley
Keyword(s):  
Column Density ◽  
Angular Resolution ◽  
Dust Emission ◽  
Line Emission ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Line Profiles ◽  
Co Emission ◽  
Continuous Strip ◽  
Made In

A fully sampled map of size ∼1′×3′ (R.A. Dec), centered on BN-KL has been made in the J = 1-0 line of 12C18O with 21″ angular resolution. The 12C18O emission is concentrated in a ← 40″ wide continuous strip running S to NE. Several maxima are superposed on the ridge, but none exceeds the average emission level by more than 40%. There is no intense peak of 12C18O J = 1-0 line emission centered on BN-KL, in contrast to maps of the dust emission. The dust and 12C18O results can be reconciled with a constant (CO/H2) ratio if there are variations in the kinetic temperature and column density of ∼50%. Peaks in both temperature and column density are then located near BN-KL, and 90″ to the south. From the estimated CO column density, about 10% of the carbon is in the form of CO. Near the BN-KL region, the 12C18O line profiles tend to become wider. These wider lines appear to be superposed on a weak, 18 km s−1 (FWHP) wide pedestal. In regions 40″ NE and 30″ S of BN-KL, the 12C18O lines have widths of less than 2 km s−1. Presumably, these are the locations of high density, quiescent molecular gas. The radial velocity of the CO emission increases from 6.5 km s−1 (at 90″ S) to 10.5 km s−1 (at 60″ NE) of BN-KL. Close to BN-KL, however, there is evidence that this trend is reversed.

scholarly journals Gas Dynamics and Active Phenomena in Galactic Nuclei: M100 and M94

1996 ◽  
Vol 157 ◽  
pp. 247-249
Author(s):  
Kazushi Sakamoto ◽  
Takeo Minezaki ◽  
Keiichi Wada ◽  
Sachiko Okumura ◽  
Yukiyasu Kobayashi
Keyword(s):  
Gravitational Potential ◽  
Gas Dynamics ◽  
Molecular Clouds ◽  
Galactic Nuclei ◽  
Trace Gas ◽  
Molecular Gas ◽  
Barred Galaxies ◽  
Nir Imaging ◽  
Oval Distortion

Since molecular gas fuels AGNs and molecular clouds form stars, understanding of molecular gas dynamics is a key to the understanding of active phenomena (such as starbursts and AGNs) in galactic nuclei. To study gas dynamics in weakly barred galaxies, we made CO interferometry (to trace gas) and NIR imaging (to trace stars) toward two nearby SAB galaxies M100 and M94. Each galaxy has a small stellar nuclear bar and also has an outer bar or oval distortion, thus suitable for the study of gas dynamics in a barred gravitational potential. Observations were made using Nobeyama Millimeter Array (NMA) and the IRcamera PICNIC installed at the ISAS 1.3 m telescope.

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