Interstellar extinction in the direction of the Aquila Rift

Straižys, V.; Cernis, K.; Bartasiute, S.

doi:10.1051/0004-6361:20030599

Cited by 90 publications

(128 citation statements)

References 30 publications

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“…1). A distance of 225 ± 55 pc has been derived for this extinction wall, using spectro-photometric studies of the optically visible stars (Straižys et al 2003). This distance is very similar to the usually adopted distance of 260 ± 37 pc for the Serpens star-forming region 1 , located only 3 • north (Straižys et al 1996).…”

Section: Overview and Distance Of The Aquila Rift Complexmentioning

confidence: 99%

TheHerschelfirst look at protostars in the Aquila rift

Bontemps

André

Könyves

et al. 2010

A&A

120

107

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As part of the science demonstration phase of the Herschel mission of the Gould Belt key program, the Aquila rift molecular complex has been observed. The complete ∼3.3 • × 3.3 • imaging with SPIRE 250/350/500 μm and PACS 70/160 μm allows a deep investigation of embedded protostellar phases, probing of the dust emission from warm inner regions at 70 and 160 μm to the bulk of the cold envelopes between 250 and 500 μm. We used a systematic detection technique operating simultaneously on all Herschel bands to build a sample of protostars. Spectral energy distributions are derived to measure luminosities and envelope masses, and to place the protostars in an M env −L bol evolutionary diagram. The spatial distribution of protostars indicates three star-forming sites in Aquila, with W40/Sh2-64 HII region by far the richest. Most of the detected protostars are newly discovered. For a reduced area around the Serpens South cluster, we could compare the Herschel census of protostars with Spitzer results. The Herschel protostars are younger than in Spitzer with 7 Class 0 YSOs newly revealed by Herschel. For the entire Aquila field, we find a total of ∼45-60 Class 0 YSOs discovered by Herschel. This confirms the global statistics of several hundred Class 0 YSOs that should be found in the whole Gould Belt Survey.

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Section: Overview and Distance Of The Aquila Rift Complexmentioning

confidence: 99%

TheHerschelfirst look at protostars in the Aquila rift

Bontemps

André

Könyves

et al. 2010

A&A

120

107

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“…Later, several authors assigned a distance of 200 pc assuming that the clouds, L328 and L323, are located in-between the Ophiuchus cloud and the Aquila Rift (e.g., Lee et al 2009). Using photometry on the Vilnius system, Straižys et al (2003) estimated a distance of 225 ± 55 pc to the front edge of the Aquila Rift with a possible depth of 80 pc to the cloud complex. If L328 and L323 are physically associated with the Aquila Rift, then the clouds are possibly located towards its front edge.…”

Section: L328mentioning

confidence: 99%

Distances to dense cores that contain very low luminosity objects

Maheswar

Lee

Dib

2011

A&A

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Aims. We estimate the distances to dense molecular cores that harbour very low luminosity objects (VeLLOs) detected by the Spitzer Space Telescope and attempt to confirm their VeLLO nature. Methods. The cloud distances are estimated using a near-IR photometric method. We use a technique that performs a spectral classification of stars lying towards the fields containing the clouds as either main-sequence stars or giants. In this technique, the observed (J − H) and (H − K s ) colours are dereddened simultaneously using trial values of A V and a normal interstellar extinction law. The best fit of the dereddened colours to the intrinsic colours giving a minimum value of χ 2 then yields the corresponding spectral type and A V for the star. The main-sequence stars, thus classified, are then utilized in an A V versus distance plot to bracket the cloud distances. The typical error in the estimation of distances to the clouds are found to be ∼18%. Results. We estimate distances to seven cloud cores, IRAM 04191, L1521F, BHR 111, L328, L673-7, L1014, and L1148 using the above method. These clouds contain VeLLO candidates. The estimated distances to the cores are found to be 127 ± 25 pc (IRAM 04191), 136 ± 36 pc (L1521F), 355 ± 65 pc (BHR 111), 217 ± 30 pc (L328), 240 ± 45 pc (L673-7), 258 ± 50 pc (L1014), and 301 ± 55 pc (L1148). We re-evaluated the internal luminosities of the VeLLOs discovered in these seven clouds using the distances estimated from this work. Except for L1014−IRS (L int = 0.15 L ), all other VeLLO candidates are found to be consistent with the definition of a VeLLO (L int ≤ 0.1 L ). In addition to the cores that harbour VeLLO candidates, we also obtained distances to the clouds L323, L675, L676, CB 188, L1122, L1152, L1155, L1157, and L1158, which are located in the directions of the above seven cores. Towards L1521F and L1148, we found evidence of multiple dust layers.

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“…Since its first identification as an active star-forming region by Strom et al (1976), the Serpens cloud core has attracted much attention owing to its remarkably high stellar density and starformation efficiency (e.g., Enoch et al 2007) that is observed within its limited extent of a few arc-minutes (∼0.2-0.4 pc for the distance estimates ranging between 260 pc (Straižys et al 2003) and 415 ± 25 pc (Dzib et al 2010), which is the latter adapted in this work). Among the stellar population of the Serpens complex, ∼30 embedded (Class 0 & I) protostars have been identified (Winston et al 2007;Harvey et al 2007), which are distributed within two main clumps at the northwest and southeast, as opposed to a dispersed population of more evolved (Class II) protostars along the cluster.…”

Section: Introductionmentioning

confidence: 99%

Dust, ice and gas in time (DIGIT):HerschelandSpitzerspectro-imaging of SMM3 and SMM4 in Serpens

Dionatos

Jørgensen

Green

et al. 2013

A&A

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Context. Mid-and far-infrared observations of the environment around embedded protostars reveal a plethora of high excitation molecular and atomic emission lines. Different mechanisms for the origin of these lines have been proposed, including shocks induced by protostellar jets and radiation or heating by the embedded protostar of its immediate surroundings. Aims. By studying of the most important molecular and atomic coolants, we aim at constraining the physical conditions around the embedded protostars SMM3 and SMM4 in the Serpens molecular cloud core and measuring the CO/H 2 ratio in warm gas. The excitation conditions for molecular species are assessed through rotational diagrams. Emission lines from major coolants are compared to the results of steady-state C-and J-type shock models. Results. Line emission tends to peak at distances of ∼10-20 from the protostellar sources with all but [CII] peaking at the positions of outflow shocks seen in near-IR and sub-millimeter interferometric observations. The [CII] emission pattern suggests that it is most likely excited from energetic UV radiation originating from the nearby flat-spectrum source SMM6. Excitation analysis indicates that H 2 and CO originate in gas at two distinct rotational temperatures of ∼300 K and 1000 K, while the excitation temperature for H 2 O and OH is ∼100-200 K. The morphological and physical association between CO and H 2 suggests a common excitation mechanism, which allows direct comparisons between the two molecules. The CO/H 2 abundance ratio varies from ∼10 −5 in the warmer gas up to ∼10 −4 in the hotter regions. Shock models indicate that C-shocks can account for the observed line intensities if a beam filling factor and a temperature stratification in the shock front are considered. C-type shocks can best explain the emission from H 2 O. The existence of J-shocks is suggested by the strong atomic/ionic (except for [CII]) emission and a number of line ratio diagnostics. Dissociative shocks can account for the CO and H 2 emission in a single excitation temperature structure. Conclusions. The bulk of cooling from molecular and atomic lines is associated with gas excited in outflow shocks. The strong association between H 2 and CO constrain their abundance ratio in warm gas. Both C-and J-type shocks can account for the observed molecular emission; however, J-shocks are strongly suggested by the atomic emission and provide simpler and more homogeneous solutions for CO and H 2 . The variations in the CO/H 2 abundance ratio for gas at different temperatures can be interpreted by their reformation rates in dissociative J-type shocks, or the influence of both C and J shocks.

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Interstellar extinction in the direction of the Aquila Rift

Cited by 90 publications

References 30 publications

TheHerschelfirst look at protostars in the Aquila rift

TheHerschelfirst look at protostars in the Aquila rift

Distances to dense cores that contain very low luminosity objects

Dust, ice and gas in time (DIGIT):HerschelandSpitzerspectro-imaging of SMM3 and SMM4 in Serpens

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