Massive star-forming regions across the Galaxy : Initial stages of massive star formation in infrared high extinction clouds <em>and</em> Trigonometric parallaxes to 6.7GHz methanol masers

Star-forming regions trace the spiral structure of the Galaxy. They are regions of increased column density and therefore traced well by the extinction in the mid-infrared based on the Spitzer/GLIMPSE 3.6-4.5 micron color excess maps. A sample of 25 high extinction clouds (HECs) was studied in the 1.2 mm dust continuum emission, and followed up by observations of ammonia plus several other molecules using the Effelsberg 100m, IRAM 30m and APEX telescopes. With these data we want to investigate the most early stages of massive star formation, which are currently still largely unknown. Three cloud classes were defined from their morphology in the 1.2\,mm continuum maps: the early diffuse HECs, with a low contrast between the clump and cloud emission; the peaked HECs, with an increased contrast; the late multiply peaked HECs, with more than one clump and a high contrast between the clump and the cloud emission. The clouds are cold (T ~ 16 K) and massive (M ~ 800 M_sun) and contain dense clumps (n ~ 10^5 cm^{-3}) of 0.3 pc in size. These clumps were investigated for evidence of gravitational collapse or expansion, for high velocity outflows, and for the presence of young stellar objects. Based on these results we interpret the three cloud classes as an evolutionary sequence of star-forming clouds. Accurate distances are a crucial parameter for establishing the mass, size, and luminosity of an object. Also, for understanding the spiral structure of the Galaxy trustworthy distances are necessary. The most accurate method to measure these is the trigonometric parallax. Using the European Very Large Baseline Interferometry Network of radio antennas we measured, for the first time, parallaxes of 6.7 GHz methanol masers. This transition belongs to the strongest maser species in the Galaxy, it is stable and observed toward numerous massive star-forming regions. We measured distances and proper motions toward L 1287, L 1206, NGC 281-W, ON 1 and S 255, and obtained their 3-dimensional space velocities. Similar to previous studies, these star-forming regions rotate slower than Galactic rotation

Methanol Maser Parallaxes and Proper Motions

Due to their compactness, persistence and slow motion, Class II CH3OH masers are excellent targets for parallax and proper motion measurements for massive star-forming regions in the Galactic Disk. These measurements can be used to improve our understanding of the spiral structure and dynamics of the Milky Way. At the same time, Class II CH3OH masers can also be used to study gas kinematics close to the exciting star, tracing rotation, infall and/or outflow motions

KAFE: the Key-analysis Automated FITS-images Explorer

We present KAFE—the Key-analysis Automated FITS-images Explorer. KAFE is a web-based FITS image postprocessing analysis tool designed to be applicable in the radio to sub-mm wavelength domain. KAFE was developed to complement selected FITS files with metadata based on a uniform image analysis approach as well as to provide advanced image diagnostic plots. It is ideally suited for data mining purposes and multiwavelength/multi-instrument data samples that require uniform data diagnostic criteria. We present the code structure and interface, the keyword definitions, the products generated for selected users’ science cases, and application examples

The Forgotten Quadrant Survey

The Forgotten Quadrant Survey (FQS) is an ESO large project at the 12-m Kitt Peak antenna of the Arizona Radio Observatory with the aim to map the Galactic Plane in the range 220\degr12CO (1-0), and 13CO (1-0). FQS will produce a dataset of great legacy value, largely improving the data quality both in terms of sensitivity and spatial resolution over existing datasets, in this poorly studied portion of the outer Galaxy. FQS contributes to the general effort to produce a new generation of high-quality spectroscopic data for the Galactic Plane. Such data, in conjunction with the latest generation continuum surveys, will produce a new and more detailed picture of the plane of the Milky Way

VizieR Online Data Catalog: Catalog of dense cores in Aquila from Herschel (Konyves+, 2015)

Based on Herschel Gould Belt survey (Andre et al., 2010A&A...518L.102A) observations of the Aquila cloud complex, and using the multi-scale, multi-wavelength source extraction algorithm getsources (Men'shchikov et al., 2012A&A...542A..81M), we identified a total of 749 dense cores, including 685 starless cores and 64 protostellar cores. The observed properties of all dense cores are given in tablea1.dat, and their derived properties are listed in tablea2.dat. (4 data files)

Square Kilometre Array Science Data Challenge 1: analysis and results

As the largest radio telescope in the world, the Square Kilometre Array (SKA) will lead the next generation of radio astronomy. The feats of engineering required to construct the telescope array will be matched only by the techniques developed to exploit the rich scientific value of the data. To drive forward the development of efficient and accurate analysis methods, we are designing a series of data challenges that will provide the scientific community with high-quality data sets for testing and evaluating new techniques. In this paper, we present a description and results from the first such Science Data Challenge 1 (SDC1). Based on SKA MID continuum simulated observations and covering three frequencies (560, 1400, and 9200 MHz) at three depths (8, 100, and 1000 h), SDC1 asked participants to apply source detection, characterization, and classification methods to simulated data. The challenge opened in 2018 November, with nine teams submitting results by the deadline of 2019 April. In this work, we analyse the results for eight of those teams, showcasing the variety of approaches that can be successfully used to find, characterize, and classify sources in a deep, crowded field. The results also demonstrate the importance of building domain knowledge and expertise on this kind of analysis to obtain the best performance. As high-resolution observations begin revealing the true complexity of the sky, one of the outstanding challenges emerging from this analysis is the ability to deal with highly resolved and complex sources as effectively as the unresolved source population

VizieR Online Data Catalog: Hi-GAL. inner Milky Way: +68>=l>=70 (Molinari+, 2016)

This is the first public data release of high-quality products from the Herschel Hi-GAL survey. The release comes two years after the end of the Herschel observing campaign and is the result of extensive testing of the data reduction and extraction procedures created by members of the Hi-GAL consortium. The complexity and the large variation of the background conditions in all Herschel wavelength bands makes source extraction on the Galactic plane a challenging task. With Hi-GAL DR1, we provide access (http://vialactea.iaps.inaf.it) through a cutout service to high-quality images and compact source catalogues for the Galactic plane at 70, 160, 250, 350, and 500um in the region 68°>=l>=-70° and |b|<= 1°

Event Horizon Telescope observations of the jet launching and collimation in Centaurus A

Abstract: Very-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimetre wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to 10–100 gravitational radii (rg ≡ GM/c2) scales in nearby sources1. Centaurus A is the closest radio-loud source to Earth2. It bridges the gap in mass and accretion rate between the supermassive black holes (SMBHs) in Messier 87 and our Galactic Centre. A large southern declination of −43° has, however, prevented VLBI imaging of Centaurus A below a wavelength of 1 cm thus far. Here we show the millimetre VLBI image of the source, which we obtained with the Event Horizon Telescope at 228 GHz. Compared with previous observations3, we image the jet of Centaurus A at a tenfold higher frequency and sixteen times sharper resolution and thereby probe sub-lightday structures. We reveal a highly collimated, asymmetrically edge-brightened jet as well as the fainter counterjet. We find that the source structure of Centaurus A resembles the jet in Messier 87 on ~500 rg scales remarkably well. Furthermore, we identify the location of Centaurus A’s SMBH with respect to its resolved jet core at a wavelength of 1.3 mm and conclude that the source’s event horizon shadow4 should be visible at terahertz frequencies. This location further supports the universal scale invariance of black holes over a wide range of masses5, 6

a Herschel Look to Star Formation in the Third Galactic Quadrant

The first Hi-GAL observations of the outer Galaxy consist of five dust continuum maps, between 70 and 500 μm, of the area delimited by 216.5° < ℓ < 225.5° and -2° < b < 0°). NANTEN CO(1-0) line observations are used to derive cloud kinematics and distances, making it possible to estimate physical parameters of the compact sources (cores and clumps) detected in the region, namely 255 proto-stellar and 590 pre-stellar sources, respectively. Both source typologies are found in all the distance components observed in the field, up to - 5.8 kpc, testifying the presence of star formation beyond the Perseus arm at these longitudes. Furthermore, several sources of both protoand pre-stellar nature are compatible with requirements for massive star formation, based on the mass-radius relation. For the pre-stellar sources belonging to the Local arm (d < 1.5 kpc) we study the mass function, whose high-mass end shows a power-law behavior N(logM) ˜ M^(-1.0±0.2). Finally, we use a luminosity versus mass diagram to infer the evolutionary status of the sources, finding that most of the proto-stellar are in the early accretion phase (with some cases compatible with a Class-I stage), while for pre-stellar sources, in general, accretion has not started yet

The Hi-GAL compact source catalogue - I. The physical properties of the clumps in the inner Galaxy (-71.0° < ℓ < 67.0°)

Hi-GAL (Herschel InfraRed Galactic Plane Survey) is a large-scale survey of the Galactic plane, performed with Herschel in five infrared continuum bands between 70 and 500 μm. We present a band-merged catalogue of spatially matched sources and their properties derived from fits to the spectral energy distributions (SEDs) and heliocentric distances, based on the photometric catalogues presented in Molinari et al., covering the portion of Galactic plane -71.0° < ℓ < 67.0°. The band-merged catalogue contains 100 922 sources with a regular SED, 24 584 of which show a 70-μm counterpart and are thus considered protostellar, while the remainder are considered starless. Thanks to this huge number of sources, we are able to carry out a preliminary analysis of early stages of star formation, identifying the conditions that characterize different evolutionary phases on a statistically significant basis. We calculate surface densities to investigate the gravitational stability of clumps and their potential to form massive stars. We also explore evolutionary status metrics such as the dust temperature, luminosity and bolometric temperature, finding that these are higher in protostellar sources compared to pre-stellar ones. The surface density of sources follows an increasing trend as they evolve from pre-stellar to protostellar, but then it is found to decrease again in the majority of the most evolved clumps. Finally, we study the physical parameters of sources with respect to Galactic longitude and the association with spiral arms, finding only minor or no differences between the average evolutionary status of sources in the fourth and first Galactic quadrants, or between 'on-arm' and 'interarm' positions