L. Cambrésy

The Aquila prestellar core population revealed by Herschel

The origin and possible universality of the stellar initial mass function (IMF) is a major issue in astrophysics. One of the main objectives of the Herschel Gould Belt Survey is to clarify the link between the prestellar core mass function (CMF) and the IMF. We present and discuss the core mass function derived from Herschel data for the large population of prestellar cores discovered with SPIRE and PACS in the Aquila Rift cloud complex at d ~ 260 pc. We detect a total of 541 starless cores in the entire ~11 deg^2 area of the field imaged at 70-500 micron with SPIRE/PACS. Most of these cores appear to be gravitationally bound, and thus prestellar in nature. Our Herschel results confirm that the shape of the prestellar CMF resembles the stellar IMF, with much higher quality statistics than earlier submillimeter continuum ground-based surveys.

Filamentary structures and compact objects in the Aquila and Polaris clouds observed by Herschel

Our PACS and SPIRE images of the Aquila Rift and part of the Polaris Flare regions, taken during the science demonstration phase of Herschel discovered fascinating, omnipresent filamentary structures that appear to be physically related to compact cores. We briefly describe a new multi-scale, multi-wavelength source extraction method used to detect objects and measure their parameters in our Herschel images. All of the extracted starless cores (541 in Aquila and 302 in Polaris) appear to form in the long and very narrow filaments. With its combination of the far-IR resolution and sensitivity, Herschel directly reveals the filaments in which the dense cores are embedded; the filaments are resolved and have deconvolved widths of 35 arcsec in Aquila and 59 arcsec in Polaris (9000 AU in both regions). Our first results of observations with Herschel enable us to suggest that in general dense cores may originate in a process of fragmentation of complex networks of long, thin filaments, likely formed as a result of an interplay between gravity, interstellar turbulence, and magnetic fields. To unravel the roles of the processes, one has to obtain additional kinematic and polarization information; these follow-up observations are planned.

The Herschel ? first look at protostars in the Aquila Rift ??

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 ~ 3.3deg x 3.3deg imaging with SPIRE 250/350/500 micron and PACS 70/160 micron allows a deep investigation of embedded protostellar phases, probing of the dust emission from warm inner regions at 70 and 160 micron to the bulk of the cold envelopes between 250 and 500 micron. 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.

A Herschel study of the properties of starless cores in the Polaris Flare dark cloud region using PACS and SPIRE

The Polaris Flare cloud region contains a great deal of extended emission. It is at high declination and high Galactic latitude. It was previously seen strongly in IRAS Cirrus emission at 100 microns. We have detected it with both PACS and SPIRE on Herschel. We see filamentary and low-level structure. We identify the five densest cores within this structure. We present the results of a temperature, mass and density analysis of these cores. We compare their observed masses to their virial masses, and see that in all cases the observed masses lie close to the lower end of the range of estimated virial masses. Therefore, we cannot say whether they are gravitationally bound prestellar cores. Nevertheless, these are the best candidates to be potential prestellar cores in the Polaris cloud region.

L183 (L134n) revisited. II. The dust content

We present here a complete dust map of L183 (=L134N) with opacities ranging from A V = 3 to 150 mag. Five peaks are identified as being related to known molecular peaks and among these dust peaks two are liable to form stars. The main peak is a prestellar core with a density profile proportional to r -1 up to a radius of ~4500 AU and the northern peak could possibly be on its way to form a prestellar core. If true, this is the first example of the intermediate steps between cloud cores and prestellar cores during the quasi-static contraction. Additionally, the low dust temperature of the core reported in Pagani et al. ([CITE]) is confirmed, and the ISOPHOT data are shown to be inappropriate for finding such cores. In the inner core,

L183 (L134N) Revisited - I. The very cold core and the ridge

T_\mathrm{dust} \approx 7.5

Variation of the extinction law in the Trifid nebula

K and could be as low as 6.7 K.

Hierarchical progressive surveys - Multi-resolution HEALPix data structures for astronomical images, catalogues, and 3-dimensional data cubes

We report new 1.2 mm continuum observations of the L183 (=L134N) dark cloud with the MAMBO bolometer array at IRAM. Combined with ISOCAM and ISOPHOT data at 7 and 200 μ m, this new observation is not compatible with the results found by Ward-Thompson et al. (1994) with SCUBA and further analysed by Lehtinen et al. (2003) using ISOPHOT data. Only one bright core, with a northern elongation (the ridge) is detected. We show that this core has an average temperature

Young stellar clusters in the Rosette molecular cloud Arguments against triggered star formation

T \approx 7.6~{\rm K} \pm0.5

Modeling and predicting the shape of the far-infrared to submillimeter emission in ultra-compact HII regions and cold clumps

K which is one of the coldest temperatures reported so far.