The environment of the infrared dust bubble N65: a mutiwavelength study

AIMS: We investigate the environment of the infrared dust bubble N65 and search for evidence of triggered star formation in its surroundings. METHODS: We performed a multiwavelength study of the region around N65 with data taken from large-scale surveys: Two Micron All Sky Survey, GLIMPSE, MIPSGAL, SCUBA, and GRS. We analyzed the distribution of the molecular gas and dust in the environment of N65 and performed infrared photometry and spectral analysis of point sources to search for young stellar objects and identify the ionizing star candidates. RESULTS: We found a molecular cloud that appears to be fragmented into smaller clumps along the N65 PDR. This indicates that the so-called collect and collapse process may be occurring. Several young stellar objects are distributed among the molecular clumps. They may represent a second generation of stars whose formation was triggered by the bubble expanding into the molecular gas. We dentified O-type stars inside N65, which are the most reliable ionizing star candidates.Comment: 15 pages, 10 figures, accepted for publication in A&A. Figures degraded to reduce file siz

The HII region G35.673-00.847: another case of triggered star formation?

As part of a systematic study that we are performing with the aim to increase the observational evidence of triggered star formation in the surroundings of HII regions, we analyze the ISM around the HII region G35.673-00.847, a poorly studied source. Using data from large-scale surveys: Two Micron All Sky Survey, Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), MIPSGAL, Galactic Ring Survey (GRS), VLA Galactic Plane Survey (VGPS), and NRAO VLA Sky Survey (NVSS) we performed a multiwavelength study of G35.673-00.847 and its surroundings. The mid IR emission, shows that G35.673-00.847 has an almost semi-ring like shape with a cut towards the galactic west. The radius of this semi-ring is about 1.5' (~1.6 pc, at the distance of ~3.7 kpc). The distance was estimated from an HI absorption study and from the analysis of the molecular gas. Indeed, we find a molecular shell composed by several clumps distributed around the HII region, suggesting that its expansion is collecting the surrounding material. We find several YSO candidates over the molecular shell. Finally, comparing the HII region dynamical age and the fragmentation time of the molecular shell, we discard the collect and collapse as the mechanism responsible for the YSOs formation, suggesting other processes such as radiative driven implosion and/or small-scale Jeans gravitational instabilities.Comment: Accepted for publication in A&A, 18 October 2010. Some figures were degraded to reduce file siz

Triggered massive-star formation on the borders of Galactic HII regions. IV- Star formation at the periphery of Sh2-212

Aims: We wish to establish whether sequential star formation is taking place at the periphery of the Galactic HII region Sh2-212. Methods: We present CO millimetre observations of this region obtained at the IRAM 30-m telescope to investigate the distribution of associated molecular material. We also use deep JHK observations obtained at the CFHT to study the stellar content of the region, and radio observations obtained at the VLA to look for the presence of an ultra-compact (UC) HII region and for maser emission. Results: In the optical, Sh2-212 is spherically symmetric around its central exciting cluster. This HII region is located along a molecular filament. A thin, well-defined half ring of molecular material surrounds the brightest part of the HII region at the rear and is fragmented. The most massive fragment (~200 solar masses) contains a massive young stellar object displaying a near-IR excess; its spectral energy distribution indicates a high-mass (~14solar masses), high-temperature (~30000K), and high-luminosity (~17000 solar luminosities) source. This object ionizes a UC HII region. Conclusions: Sh2-212 is a good example of massive-star formation triggered via the collect and collapse process. The massive YSO observed at its periphery is a good candidate for a massive star formed in isolation.Comment: 12 pages, 14 figures. To be published in A&

The infrared dust bubble N22: an expanding HII region and the star formation around it

Aims. To increase the observational samples of star formation around expanding Hii regions, we analyzed the interstellar medium and star formation around N22. Methods. We used data extracted from the seven large-scale surveys from infrared to radio wavelengths. In addition we used the JCMT observations of the J = 3-2 line of 12CO emission data released on CADC and the 12CO J = 2-1 and J =3-2 lines observed by the KOSMA 3 m telescope. We performed a multiwavelength study of bubble N22. Results. A molecular shell composed of several clumps agrees very well with the border of N22, suggesting that its expansion is collecting the surrounding material. The high integrated 12CO line intensity ratio (ranging from 0.7 to 1.14) implies that shocks have driven into the molecular clouds. We identify eleven possible O-type stars inside the Hii region, five of which are located in projection inside the cavity of the 20 cm radio continuum emission and are probably the exciting-star candidates of N22. Twenty-nine YSOs (young stellar objects) are distributed close to the dense cores of N22. We conclude that star formation is indeed active around N22; the formation of most of YSOs may have been triggered by the expanding of the Hii region. After comparing the dynamical age of N22 and the fragmentation time of the molecular shell, we suggest that radiation-driven compression of pre-existing dense clumps may be ongoing.Comment: accepted in A&A 30/05/2012. arXiv admin note: text overlap with arXiv:1010.5430 by other author

Spitzer/IRAC view of Sh 2-284: Searching for evidence of triggered star formation in an isolated region in the outer Milky Way

Using Spitzer/IRAC observations of a region to be observed by the CoRoT satellite, we have unraveled a new complex star-forming region at low metallicity in the outer Galaxy. We perform a study of S284 in order to outline the chain of events in this star-forming region. We used four-band Spitzer/IRAC photometry as well as Halpha imaging obtained with INT/WFC. Combining these data with the optical photometry obtained in the frame of CoRoTs preparation and the 2MASS catalog we analysed the properties and distribution of young stellar objects (YSOs) associated with point-like sources. We also studied the SEDs of regions of extended emission, complementing our dataset with IRAS and MSX data. We find that S284 is unique in several ways: it is very isolated at the end of a spiral arm and both the diffuse dust and ionized emission are remarkably symmetric. We have partially resolved the central clusters of the three bubbles present in this region. Despite the different scales present in its multiple-bubble morphology, our study points to a very narrow spread of ages among the powering high-mass clusters. In contrast, the particular sawtooth structure of the extended emission at the rim of each ionized bubble harbours either small lower-mass clusters with a younger stellar population or individual young reddened protostars. In particular, triggered star formation is considered to be at work in these regions.Comment: Accepted by A&A. 13 pages, 10 figures, 2 Table

The Ap 2-1 nebula and the surrounding molecular cloud G35.2-0.74: an active star forming region

Using data from large-scale surveys: 2MASS, GLIMPSE, MIPSGAL, VGPS, GRS, and IPHAS, we performed a multiwavelength study of the ISM in a region of about 20' x 20' towards the molecular cloud G35.2-0.74. Additionally, the Ap 2-1 nebula, that is seen in projection over the molecular cloud, was studied using optical data obtained with the 2.15 m telescope at CASLEO, Argentina. From the HI absorption study we estimate a distance of ~2 kpc for Ap 2-1 confirming that the nebula is embedded in the south portion of the molecular cloud G35.2-0.74. Performing a photometric study and analysing the spectral energy distributions of the sources likely embedded in the cloud, we confirm that this region is very active in star formation, mainly towards the north, where we discover a cluster of young stellar objects. From the H_alpha and [NII] lines we obtain a radial velocity of v_LSR ~ 31 km/s for the Ap 2-1 nebula, in coincidence with the velocity of the molecular cloud. Finally, we conclude that Ap 2-1 is an HII region probably excited by an early B-type star.Comment: 9 pages, 10 figures, accepted to be published in MNRAS (July 5, 2010

Triggered star formation on the borders of the Galactic HII region RCW 82

We are engaged in a multi-wavelength study of several Galactic HII regions that exhibit signposts of triggered star formation on their borders, and where the collect and collapse process could be at work. When addressing the question of triggered star formation it is critically important to ensure the real association between the ionized gas and the neutral material observed nearby. In this paper we stress this point, and present CO observations of the RCW 82 star forming region. The velocity distribution of the molecular gas is combined with the study of young stellar objects (YSOs) detected in the direction of RCW 82. We discuss the YSO's evolutionary status using near- and mid-IR data. The spatial and velocity distributions of the molecular gas are used to discuss the possible scenarios for the star formation around RCW 82.Comment: 17 pages, 20 figures. Accepted by A&

Hi-GAL: The Herschel Infrared Galactic Plane Survey

Hi-GAL, the Herschel infrared Galactic Plane Survey, is an Open Time Key Project of the Herschel Space Observatory. It will make an unbiased photometric survey of the inner Galactic plane by mapping a 2° wide strip in the longitude range ∣l∣ < 60° in five wavebands between 70 μm and 500 μm. The aim of Hi-GAL is to detect the earliest phases of the formation of molecular clouds and high-mass stars and to use the optimum combination of Herschel wavelength coverage, sensitivity, mapping strategy, and speed to deliver a homogeneous census of star-forming regions and cold structures in the interstellar medium. The resulting representative samples will yield the variation of source temperature, luminosity, mass and age in a wide range of Galactic environments at all scales from massive YSOs in protoclusters to entire spiral arms, providing an evolutionary sequence for the formation of intermediate and high-mass stars. This information is essential to the formulation of a predictive global model of the role of environment and feedback in regulating the star-formation process. Such a model is vital to understanding star formation on galactic scales and in the early universe. Hi-GAL will also provide a science legacy for decades to come with incalculable potential for systematic and serendipitous science in a wide range of astronomical fields, enabling the optimum use of future major facilities such as JWST and ALMA

Traumatics amputations of the upper limb : The patients journey for the reconstruction of their bodily continuity

Introduction : Nous proposons dans ce travail, un regroupement de 4 études permettant d’évaluer le devenir psychologique des patients victimes d’une amputation traumatique au membre supérieur, où les solutions chirurgicales n’ont pu permettre la conservation du fragment amputé. Ces 4 études ont pour objectifs principaux, savoir : La première, de préciser l’incidence des amputations traumatiques au membre supérieur. La deuxième, de déterminer l’existence d’un deuil pathologique traumatique après la survenue d’une amputation traumatique au membre supérieur. La troisième, d’évaluer la proportion de patients victimes d’une amputation traumatique du membre supérieur affirmant avoir surmonté les conséquences de l’accident et ne présentant pas de deuil pathologique. La quatrième, d’apprécier les motivations des patients demandeurs d’une amputation secondaire d’un doigt long après un accident de travail comparativement aux patients blessés hors accidents de travail. Matériel & Méthodes : Il s’agit d’un travail rétrospectif mené sur une période de 11 ans, au sein d’un SOS Mains adulte. Les dossiers des patients pris en charge pour une amputation traumatique ont été recherchés. Cette sélection a été réalisée à l’aide des codes CCAM des actes de régularisations et de replantations au membre supérieur. Seules les amputations traumatiques complètes du membre supérieur et pris en charge ont été recensées. L’ensemble des niveaux anatomiques a été considéré. Les amputations non traumatiques et/ou incomplètes ont été exclues de même que la population pédiatrique (âge inférieur à 16 ans). Pour la première étude, nous avons déterminé l’incidence des amputations traumatiques ainsi que la proportion de tentatives de replantations, et ses échecs. Le profil épidémiologique des patients a également été étudié. Pour la deuxième étude, nous avons établi la proportion de deuil pathologique traumatique dans la population des patients amputés au membre supérieur sans solutions chirurgicales ou après échec d’une replantation. Les facteurs de risque de deuil pathologique ont été étudiés. Pour la troisième étude, nous avons tenté de déterminer chez les patients victimes d’une amputation traumatique du membre supérieur, l’existence d’une corrélation entre l’absence de deuil pathologique traumatique et le sentiment personnel d’être revenu à l’état antérieur. Pour la quatrième étude, nous avons apprécié les motivations des patients demandeurs d’une amputation secondaire basimétacarpienne en fonction de la survenue de cet accident dans le contexte professionnel ou non. Résultats : Première étude : Sur la période donnée, nous avons identifié 1715 amputations traumatiques, et identifié une incidence annuelle à hauteur de 3% dans la population admise aux urgences mains. L’incidence des replantations était de 1%, avec 583 cas identifiés. Deuxième étude : Sur les 524 patients inclus, un état de deuil pathologique traumatique était identifié dans 39% des cas. L’amputation du pouce était un facteur de risque de deuil pathologique de même que l’absence de tentative de replantation. Troisième étude : Les patients affirmant avoir surmonté les causes de l’accident ne présentaient jamais d’arguments pour un deuil pathologique traumatique. À l’inverse, la totalité des patients présentant un syndrome de deuil pathologique confirmait ne pas avoir réussi à surmonter les conséquences de l’accident. Quatrième étude : La survenue de cet accident sur le lieu de travail influençait les motivations des patients demandeurs d’une amputation secondaire. Discussion : L’incidence des amputations traumatiques dans la population des patients d’un SOS Mains reste faible, mais l’importance du retentissement fonctionnel, psychologique, et social ne doit pour autant être négligée. Ce traumatisme est à l’origine d’un deuil pathologique traumatique dans plus d’un tiers des cas. Cette complication doit être dépistée systématiquement et précocement afin d’en réduire l’impact dans la vie [...]Introduction: This thesis comprises four separate studies that assessed the psychological status of patients who underwent traumatic amputations of the upper limb due to a lack of surgical options that could have prevented part of the limb from being amputated. The main objectives of these four studies were to: Firt study, identify the cases that involved traumatic amputation of the upper limb. Second study, determine the occurrence of pathological traumatic grief following upper limb traumatic amputation. Third study, assess the proportion of patients who had undergone an upper limb traumatic amputation who claimed to have overcome the direct functional consequences of the accident and who did not exhibit signs of pathological grief. Fourth study, assess whether patients more often seek a secondary amputation of a long finger injured in a work accident compared to other types of accidents. Materials & Methods: This thesis was carried out over the course of 11 years at an ‘SOS Mains Adulte’ unit. It involved collection of the medical records of patients treated for a traumatic amputation, using the CCAM (the French Common Classification of Medical Procedures) codes for upper limb rectifications and transplants. Only information regarding full and supported traumatic amputations of the upper limb was compiled. All anatomical levels were considered. Non-traumatic and/or incomplete amputations were excluded, as was the pediatric population (patients under 16 years of age). In the first study, we determined the incidence of traumatic amputations, as well as the proportion of transplant attempts and the failure rate. The epidemiological profiles of the patients were also studied. In the second study, we established the proportion of pathological traumatic mourning in the population of amputated upper limb patients for whom there was not a surgical solution or who could not be successfully transplanted. The risk factors for pathological mourning were also studied. In the third study, we assessed whether there was a correlation between the absence of traumatic pathological mourning and the personal feeling of having returned to the original state in patients who had undergone traumatic upper limb amputations. In the fourth study, we assessed whether patients were more likely to seek a secondary metacarpal base amputation based on whether the accident had taken place in the workplace. Results: The first study: Over the period in question, we identified 1,715 traumatic amputations and an annual incidence of 3% in the population admitted to the emergency department. A transplant was involved in 1%, with 583 identified cases. The second study: A state of traumatic pathological mourning was identified in 39% of the 524 included patients. Both thumb amputation and transplant failure were risk factors for pathological mourning. The third study: None of the patients who claimed to have overcome the direct functional consequences of the accident also suffered from traumatic pathological mourning. Conversely, all of the patients with pathological mourning syndrome stated that they had not been able to overcome the direct functional consequences of the accident. The fourth study: The patients were more likely to seek a secondary amputation when the accident had taken place in the workplace Discussion: Although the incidence of traumatic amputations in the population of ‘SOS Mains’ patients is low, the extent of the functional, psychological, and social repercussions should not be trivialized. Indeed, this type of trauma leads to pathological traumatic mourning in more than a third of cases. This complication following amputation needs to be detected in a systematic and timely manner in order to reduce the impact of traumatic amputation of the upper limb on the lives of victims. However, the absence of traumatic pathological mourning is not synonymous with recovery after the occurrence of an amputation. It is important to assess [...