The largest molecular cloud complexes in the first galactic quadrant

Dame, T. M.; Elmegreen, Bruce G.; Cohen, R. S.; Thaddeus, P.

doi:10.1086/164304

Cited by 339 publications

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“…Environment W44 lies in a complex region of the sky, in close proximity to several molecular clouds (Sato 1986), in a giant molecular cloud (GMC) complex (Dame 1983 ;Dame et al 1986), and at the base of the Aquila Supershell (Maciejewski et al 1996). The ambient density in which the remnant evolves is fairly high (averaging about 6 cm~3, from our results below), presumably because of its GMC environment.…”

Section: Survey Of Observationsmentioning

confidence: 67%

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

Cox

Shelton

Maciejewski

et al. 1999

ApJ

165

222

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We show that many observations of W44, a supernova remnant in the Galactic plane at a distance of about 2500 pc, are remarkably consistent with the simplest realistic model. The model remnant is evolving in a smooth ambient medium of fairly high density, about 6 cm~3 on average, with a substantial density gradient. At the observed time it has an age of about 20,000 yr, consistent with the age of the associated pulsar, and a radius of 11È13 pc. Over most of the outer surface, radiative cooling has become important in the postshock gas ; on the denser end there has been sufficient compression of the cooled gas to develop a very thin dense half-shell of about 450 supported against further compression by M _ , nonthermal pressure. The half-shell has an expansion velocity of about 150 km s~1 and is bounded on the outer surface by a radiative shock with that speed. The deep interior of the remnant has a substantial and fairly uniform pressure, as expected from even highly idealized adiabatic models ; our model, however, is never adiabatic. Thermal conduction, while the remnant is young and hot, reduces the need for expansion cooling and prevents formation of the intensely vacuous cavity characteristic of adiabatic evolution. It radically alters the interior structure from what one might expect from familiarity with the Sedov solution. At the time of observation, the temperature in the center is about 6 ] 106 K, the density about 1 cm~3. The temperature decreases gradually away from the center, while the density rises. Farther out, where cooling is becoming important, the pressure drops precipitously, and the temperature in the denser gas there is quite low. We provide several analytic tools for the assembly of models of this type. We review the early evolution and shell formation analyses and their generalizations to evolution in a density gradient. We also calculate the density and temperature that should be present in the hot interior of a remnant with thermal conduction. We supply the van der Laan mechanism in a particularly useful form for the calculation of radio continuum from radiative remnants. Finally, we estimate the optical emission that should be present from Ñuorescence of UV light, emitted by the forming shell and the radiative shock and absorbed in the cold shell and the ambient medium, and the associated 63 km [O I] emission. Both are in agreement with the intensity and spatial structures found in recent observations. Neither requires interaction with a dense molecular cloud for its generation. We calculate the gamma rays that should be emitted by cosmic-ray electrons and ions in the shell, interacting with the cold material, and Ðnd each capable of generating about 25% of the Ñux reported by EGRET for the vicinity.

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Section: Survey Of Observationsmentioning

confidence: 67%

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

Cox

Shelton

Maciejewski

et al. 1999

ApJ

165

222

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“…Dame et al 1986;Jacq et al 1988). Objects are grouped together if their position and velocity fall within the spatial extent and velocity width of the GMC.…”

Section: Distance Recommendation: Resolution Of the Kinematic Distancmentioning

confidence: 99%

“…"Wat", "SW", "A" correspond to radio sources listed mainly in Watson et al (2003), Sewilo (2004) and . The molecular information is from Dame et al (1986) for "GMC", from Roman-Duval et al (2009) for "GRSMC" clouds, from Solomon et al (1987) for "Sol" clouds, from Jacq et al (1988) for "Bx" clouds and from Simon et al (2006) and Jackson et al (2008) for "IRDC". For "GMC" and "Bx" clouds the radius and velocity FWHM of the cloud is given in brackets.…”

Section: Appendix A: Figuresmentioning

confidence: 99%

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

Russeil

Pestalozzi

Mottram

et al. 2011

A&A

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Context. Hi-GAL, an open time key-project of the Herschel satellite, was awarded 343 hours observing time to carry out a 5-band photometric imaging survey at 70, 160, 250, 350, and 500 μm of a |b| ≤ 1 • wide strip of the Milky Way Galactic plane in the longitude range −70 • ≤ l ≤ 70 • . Two 2 • × 2 • fields centred at l = 30 • and l = 59 • have been observed with the SPIRE and PACS photometric cameras in parallel mode during the Herschel science demonstration phase (SDP). From the images, compact sources are extracted for which the distance must be established in order to determine their physical properties. Aims. The aim of this paper is to present the distance determination strategy for the Hi-GAL compact sources. We illustrate this strategy for the two fields at l = 30 • and l = 59 • . Methods. The first step to determine the distance is to establish the LSR (local standard of rest) velocity of each compact source. The kinematic distance is then determined assuming a rotation curve for our Galaxy. To resolve the distance ambiguity for sources within the solar circle, we adopt a multiwavelength approach combining extinction maps, optical, and near infrared images, and velocity information from NH 3 , CO and HI data. When sources can be kinematically linked to optical H ii regions, the stellar distance of the exciting stars, when known, can be attributed to all linked sources. Results. In the two 2 • × 2 • SDP fields, 2678 compact sources have been identified and listed in the band-merged catalogue. About 93% of these sources have been assigned a radial velocity and distance. Conclusions. A multiwavelength approach is necessary to assign the correct velocity to sources (especially when CO spectra have a lot of features) and to determine the distance by solving the distance ambiguity. Also, several Hi-GAL sources seem to be in the interarm region. These sources have to be investigated with dedicated programme to be compared with sources located in the spiral arms.

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“…This would then be the lower limit of the distance to GRS 1915+105. (Dame et al 1986). Among them, the two H  regions close to GRS 1915+105 are noted in the map Fig.…”

Section: Is It Possible To Constrain the Distance To Grs 1915+105 ?mentioning

confidence: 99%

On the optical extinction and distance of GRS 1915+105

Chapuis

Corbel

2004

A&A

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Abstract. Based on new millimeter and radio observations, we reevaluate the total hydrogen column density along the line of sight to the microquasar GRS 1915+105 to N H = (3.5±0.3)×10 22 cm −2 . Our value is consistent with the one derived from X-ray measurements, namely (3.8 ± 0.3) × 10 22 cm −2 (Ebisawa et al. 1998). Using the empirical law between the visual extinction and the total column density of hydrogen, A v is found to 19.6 ± 1.7 mag. This result is ∼7 mag lower than previously thought, and therefore, a reevaluation of infrared fluxes after derredening is needed. The revisited kinematic study allows to give a lower limit to the distance of GRS 1915+105 , namely 6.0 kpc. Taking into account the most accurate upper limit of distance inferred from radio data (11.2 ± 0.8 kpc, Fender et al. 1999) as well as this lower limit, this implies a distance of 9.0 ± 3.0 kpc.

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The largest molecular cloud complexes in the first galactic quadrant

Cited by 339 publications

References 0 publications

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

On the optical extinction and distance of GRS 1915+105

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