scholarly journals Selected aspects of the analysis of molecular line observations of edge-on circumbinary disks

2020 ◽  
Vol 642 ◽  
pp. A127
Author(s):  
R. Avramenko ◽  
S. Wolf ◽  
T. F. Illenseer ◽  
S. Rehberg
Keyword(s):  
Density Distribution ◽  
Line Emission ◽  
Density Waves ◽  
Molecular Line ◽  
Hydrodynamic Simulations ◽  
Spatially Resolved ◽  
Transition Area ◽  
Multi Wavelength ◽  
Inner Region ◽  
Innermost Region

Context. Inner cavities, accretion arms, and density waves are characteristic structures in the density distribution of circumbinary disks. They are the result of the tidal interaction of the non-axisymmetric gravitational forces of the central binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is most pronounced. Aims. The goal of this study is to test the feasibility of reconstructing the gas density distribution and quantifying properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations. Methods. The density distribution in circumbinary disks is calculated with 2D hydrodynamic simulations. Subsequently, molecular line emission maps are generated with 3D radiative transfer simulations. Based on these, we investigate the observability of characteristic circumbinary structures located in the innermost region for spatially resolved and unresolved disks. Results. We find that it is possible to reconstruct the inner cavity, accretion arms, and density waves from spatially resolved multi-wavelength molecular line observations of circumbinary disks seen edge-on. For the spatially unresolved observations only, an estimate can be derived for the density gradient in the transition area between the cavity and the disk’s inner rim.

scholarly journals Optical SED models of galaxy mergers

2011 ◽  
Vol 7 (S284) ◽  
pp. 193-197
Author(s):  
Gregory F. Snyder ◽  
T. J. Cox ◽  
Christopher C. Hayward ◽  
Lars Hernquist ◽  
Patrik Jonsson
Keyword(s):  
Three Dimensional ◽  
Interacting Galaxies ◽  
Galaxy Mergers ◽  
Hydrodynamic Simulations ◽  
Spatially Resolved ◽  
Multi Wavelength ◽  
Field Unit ◽  
Effects Of Feedback ◽  
Dust Attenuation ◽  
Integral Field

AbstractI discuss recent work in which we construct models of poststarburst galaxies by combining fully three-dimensional hydrodynamic simulations of galaxy mergers with radiative transfer calculations of dust attenuation. The poststarburst signatures can occur shortly after a bright starburst phase in gas-rich mergers, and thus offer a unique opportunity to study the formation of bulges and the effects of feedback. Several additional applications of spatially-resolved spectroscopic models of interacting galaxies include multi-wavelength studies of AGN/starburst diagnostics, mock integral field unit data to interpret the evolution of ULIRGs, and the ‘Green Valley’.Optical spectra of simulated major gas-rich galaxy mergers can be found at http://www.cfa.harvard.edu/~gsnyder

scholarly journals Ammonia clumps in the Orion and Cepheus clouds

1991 ◽  
Vol 147 ◽  
pp. 436-437
Author(s):  
J. Harju ◽  
C.M. Walmsley ◽  
J.G.A. Wouterloot
Keyword(s):  
Density Distribution ◽  
Column Density ◽  
Velocity Dispersion ◽  
Line Emission ◽  
Main Interest ◽  
Molecular Line ◽  
Dynamical State

We present statistics of clump properties in the Orion and Cepheus cloud complexes based on ammonia mapping observations. Surroundings of about 50 IRAS sources earlier found to have associated molecular line emission (Wouterloot, Walmsley and Henkel, 1988) were mapped in NH3(1,1) and (2,2) with the Effelsberg 100-m telescope. Our main interest has been in determining the clump sizes and masses on the basis of the ammonia column density distribution, which together with the observed velocity dispersion lead to a rough estimate of the dynamical state. We also have studied the star-clump separations which should give us estimates of the source ages. Special attention has been paid to comparison of our Orion data with the Benson and Myers (1989, hereafter BM89) results in Taurus because the linear resolutions in the two studies are similar.

scholarly journals Ammonia clumps in the Orion and Cepheus clouds

1991 ◽  
Vol 147 ◽  
pp. 436-437 ◽  
Author(s):  
J. Harju ◽  
C.M. Walmsley ◽  
J.G.A. Wouterloot
Keyword(s):  
Density Distribution ◽  
Column Density ◽  
Velocity Dispersion ◽  
Line Emission ◽  
Main Interest ◽  
Molecular Line ◽  
Dynamical State

We present statistics of clump properties in the Orion and Cepheus cloud complexes based on ammonia mapping observations. Surroundings of about 50 IRAS sources earlier found to have associated molecular line emission (Wouterloot, Walmsley and Henkel, 1988) were mapped in NH3(1,1) and (2,2) with the Effelsberg 100-m telescope. Our main interest has been in determining the clump sizes and masses on the basis of the ammonia column density distribution, which together with the observed velocity dispersion lead to a rough estimate of the dynamical state. We also have studied the star-clump separations which should give us estimates of the source ages. Special attention has been paid to comparison of our Orion data with the Benson and Myers (1989, hereafter BM89) results in Taurus because the linear resolutions in the two studies are similar.

scholarly journals Twin, Aligned Protoplanetary Disks around the Components of the Young Binary System L1551 IRS5

2001 ◽  
Vol 200 ◽  
pp. 132-135
Author(s):  
Jose M. Torrelles ◽  
Luis F. Rodríguez ◽  
Guillem Anglada
Keyword(s):  
Star Formation ◽  
Binary System ◽  
Line Emission ◽  
Protoplanetary Disks ◽  
Formation Processes ◽  
Molecular Line ◽  
Solar Systems ◽  
Physical Conditions ◽  
Spatially Resolved ◽  
Dust Sources

VLA 7 mm continuum observations carried out by Rodríguez et al. (1998) with 0.06″ resolution toward L1551 IRS5 have shown two resolved dust sources. Both sources are elongated with almost the same orientation, similar flux densities, and similar angular sizes, being interpreted by these authors as a system of twin, aligned protoplanetary disks of 10 AU radius around the components of a young binary of 50 AU separation. These protoplanetary disks, the smaller ones ever imaged at mm wavelengths, are about a factor of ten smaller than disks around isolated stars, but have enough mass to form solar systems similar to our own. The fact that the disks are aligned with each other argues in favor for long-lived planetary systems in this binary. We all look forward to the future development of interferometers such as the EVLA, SMA, and ALMA in order to characterize the physical conditions of these associated protoplanetary disks by detecting spatially resolved molecular line emission. With these upcoming interferometers it will be possible to make great strides forward in our knowledge of the star formation processes.

scholarly journals Molecular line emission in NGC 1068 imaged with ALMA

2014 ◽  
Vol 570 ◽  
pp. A28 ◽  
Author(s):  
S. Viti ◽  
S. García-Burillo ◽  
A. Fuente ◽  
L. K. Hunt ◽  
A. Usero ◽  
...  
Keyword(s):  
Line Emission ◽  
Molecular Line ◽  
Ngc 1068

scholarly journals Understanding biases in measurements of molecular cloud kinematics using line emission

2020 ◽  
Vol 498 (2) ◽  
pp. 2440-2455
Author(s):  
Yuxuan (宇轩) Yuan (原) ◽  
Mark R Krumholz ◽  
Blakesley Burkhart
Keyword(s):  
Magnetic Field ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Line Emission ◽  
Molecular Line ◽  
Velocity Dispersions ◽  
Cloud Kinematics ◽  
Measurement Biases

ABSTRACT Molecular line observations using a variety of tracers are often used to investigate the kinematic structure of molecular clouds. However, measurements of cloud velocity dispersions with different lines, even in the same region, often yield inconsistent results. The reasons for this disagreement are not entirely clear, since molecular line observations are subject to a number of biases. In this paper, we untangle and investigate various factors that drive linewidth measurement biases by constructing synthetic position–position–velocity cubes for a variety of tracers from a suite of self-gravitating magnetohydrodynamic simulations of molecular clouds. We compare linewidths derived from synthetic observations of these data cubes to the true values in the simulations. We find that differences in linewidth as measured by different tracers are driven by a combination of density-dependent excitation, whereby tracers that are sensitive to higher densities sample smaller regions with smaller velocity dispersions, opacity broadening, especially for highly optically thick tracers such as CO, and finite resolution and sensitivity, which suppress the wings of emission lines. We find that, at fixed signal-to-noise ratio, three commonly used tracers, the J = 4 → 3 line of CO, the J = 1 → 0 line of C18O, and the (1,1) inversion transition of NH3, generally offer the best compromise between these competing biases, and produce estimates of the velocity dispersion that reflect the true kinematics of a molecular cloud to an accuracy of $\approx 10{{\ \rm per\ cent}}$ regardless of the cloud magnetic field strengths, evolutionary state, or orientations of the line of sight relative to the magnetic field. Tracers excited primarily in gas denser than that traced by NH3 tend to underestimate the true velocity dispersion by $\approx 20{{\ \rm per\ cent}}$ on average, while low-density tracers that are highly optically thick tend to have biases of comparable size in the opposite direction.

scholarly journals Molecular line emission in HH54: a coherent view from near to far infrared

2006 ◽  
Vol 459 (3) ◽  
pp. 821-835 ◽  
Author(s):  
T. Giannini ◽  
C. McCoey ◽  
B. Nisini ◽  
S. Cabrit ◽  
A. Caratti o Garatti ◽  
...  
Keyword(s):  
Line Emission ◽  
Far Infrared ◽  
Molecular Line

scholarly journals Photophoresis in the circumjovian disk and its impact on the orbital configuration of the Galilean satellites

2019 ◽  
Vol 629 ◽  
pp. A106 ◽  
Author(s):  
Sota Arakawa ◽  
Yuhito Shibaike
Keyword(s):  
Density Distribution ◽  
Accretion Disks ◽  
Surface Density ◽  
Outer Region ◽  
Dust Particles ◽  
Magnetorotational Instability ◽  
Galilean Satellites ◽  
Ionization Fraction ◽  
Orbital Configuration ◽  
Inner Region

Jupiter has four large regular satellites called the Galilean satellites: Io, Europa, Ganymede, and Callisto. The inner three of the Galilean satellites orbit in a 4:2:1 mean motion resonance; therefore their orbital configuration may originate from the stopping of the migration of Io near the bump in the surface density distribution and following resonant trapping of Europa and Ganymede. The formation mechanism of the bump near the orbit of the innermost satellite, Io, is not yet understood, however. Here, we show that photophoresis in the circumjovian disk could be the cause of the bump using analytic calculations of steady-state accretion disks. We propose that photophoresis in the circumjovian disk could stop the inward migration of dust particles near the orbit of Io. The resulting dust-depleted inner region would have a higher ionization fraction, and thus admit increased magnetorotational-instability-driven accretion stress in comparison to the outer region. The increase of the accretion stress at the photophoretic dust barrier would form a bump in the surface density distribution, halting the migration of Io.

scholarly journals Stellar populations across galaxy bars in the MUSE TIMER project

2020 ◽  
Vol 637 ◽  
pp. A56 ◽  
Author(s):  
Justus Neumann ◽  
Francesca Fragkoudi ◽  
Isabel Pérez ◽  
Dimitri A. Gadotti ◽  
Jesús Falcón-Barroso ◽  
...  
Keyword(s):  
Star Formation ◽  
Major Axis ◽  
Stellar Populations ◽  
Barred Galaxies ◽  
Chemical Enrichment ◽  
Spatially Resolved ◽  
Stellar Ages ◽  
Hydrodynamical Simulations ◽  
Inner Region ◽  
Star Formation Histories

Stellar populations in barred galaxies save an imprint of the influence of the bar on the host galaxy’s evolution. We present a detailed analysis of star formation histories (SFHs) and chemical enrichment of stellar populations in nine nearby barred galaxies from the TIMER project. We used integral field observations with the MUSE instrument to derive unprecedented spatially resolved maps of stellar ages, metallicities, [Mg/Fe] abundances, and SFHs, as well as Hα as a tracer of ongoing star formation. We find a characteristic V-shaped signature in the SFH that is perpendicular to the bar major axis, which supports the scenario where intermediate-age stars (∼2 − 6 Gyr) are trapped on more elongated orbits shaping a thinner part of the bar, while older stars (> 8 Gyr) are trapped on less elongated orbits shaping a rounder and thicker part of the bar. We compare our data to state-of-the-art cosmological magneto-hydrodynamical simulations of barred galaxies and show that such V-shaped SFHs arise naturally due to the dynamical influence of the bar on stellar populations with different ages and kinematic properties. Additionally, we find an excess of very young stars (< 2 Gyr) on the edges of the bars, predominantly on the leading side, thus confirming typical star formation patterns in bars. Furthermore, mass-weighted age and metallicity gradients are slightly shallower along the bar than in the disc, which is likely due to orbital mixing in the bar. Finally, we find that bars are mostly more metal-rich and less [Mg/Fe]-enhanced than the surrounding discs. We interpret this as a signature that the bar quenches star formation in the inner region of discs, usually referred to as star formation deserts. We discuss these results and their implications on two different scenarios of bar formation and evolution.

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