Young and very young stars in NGC 3372, the Carina nebula

Results are presented of a large-scale imaging photometric study of the stellar population in the northern part of NGC 3372 with a w avelength co verage from 0.33 to 2.5 µm. All observations were made at Las Campanas Observatory . The sizes of the three stellar clusters, Tr 14, Tr 15 and Tr 16, were determined b y means of star counts. Two-colour and colour-magnitude diagrams are presented and analyzed for eac h individual cluster. The three clusters were found to b e at a similar distance from the Sun, = 2 . 7 kpc, but with very large scatter in both A V and d . suggesting drastic variations in intracluster dust densit y . Dust particle size distribution variations are eviden t resulting in wide variations in extinction law. We determined ages bet ween 3 and 60 million years for Tr 15 and bet ween less than 1 and 6 million years for Tr 14 and Tr 16. The Tr 14 cluster is partially em bedded in a dense molecular cloud that extends to wards the south west reaching its highest densit y some three arcmin from the cluster nucleus. The ric h UV field created b y the Tr14 stars ionizes most of the visible HI I region in its vicinit y and most of the radio HI I region Car I. Deep J H K images of the Car I region reveal the presence of a young, em bedded stellar population that includes several O9–B0 stars and an ultracompact HI I region.Fil: Tapia, M.. Universidad Nacional Autónoma de México; MéxicoFil: Roth, M.. Las Campanas Observatory; ChileFil: Vazquez, Ruben Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; ArgentinaFil: Persi, P.. IASFC, CNR; Itali

Mid-Infrared Imaging of NGC 6334 I

We present high-resolution (<0.5") mid-infrared Keck II images of individual sources in the central region of NGC 6334 I. We compare these images to images at a variety of other wavelengths from the near infrared to cm radio continuum and speculate on the nature of the NGC 6334 I sources. We assert that the cometary shape of the UCHII region here, NGC 6334 F, is due to a champagne-like flow from a source on the edge of a molecular clump and not a due to a bow shock caused by the supersonic motion of the UCHII region through the interstellar medium. The mid-infrared emission in concentrated into an arc of dust that define the boundary between the UCHII region and the molecular clump. This dust arc contains a majority of the masers in the region. We discuss the nature of the four near-infrared sources associated with IRS-I 1, and suggest that one of the sources, IRS1E, is responsible for the heating and ionizing of the UCHII region and the mid-infrared dust arc. Infrared source IRS-I 2, which has been thought to be a circumstellar disk associated with a linear distribution of methanol masers, is found not to be directly coincident with the masers and elongated at a much different position angle. IRS-I 3 is found to be a extended source of mid-infrared emission coming from a cluster of young dusty sources seen in the near-infrared.Comment: Accepted for publication by the Astrophysical Journal, 27 pages, 9 figure

The First Detailed Look at a Brown Dwarf Disk

The combination of mid-infrared and recent submm/mm measurements allows us to set up the first comprehensive spectral energy distribution (SED) of the circumstellar material around a young Brown Dwarf. Simple arguments suggest that the dust is distributed in the form of a disk. We compare basic models to explore the disk parameters. The modeling shows that a flat disk geometry fits well the observations. A flared disk explains the SED only if it has a puffed-up inner rim and an inner gap much larger than the dust sublimation radius. Similarities and differences with disks around T Tauri stars are discussed.Comment: 11 pages, 1 figur

The distant young embedded stellar cluster CBJC 8 associated with G085.40-0.00

The infrared cluster CBJC 8 is associated with a 6.7 GHz methanol maser and a compact radio-continuum source, G85.40-0.00. It is located at a distance of about 8 kpc. Aims. The aim is to study the characteristics of this distant and compact embedded cluster and derive the properties of its stellar population. Methods. We present new ground-based near- and mid-infrared imaging observations of this region. The calibrated images were analysed together with archive Spitzer IRAC images. Results. Based on the discovery of a considerable fraction of embedded sources with infrared excess emission that are concentrated within a radius around 16" centred near the position of the compact HII region G85.40-0.00, we were able to confirm the presence of a very young embedded cluster. It was found to contain more than 58 members brighter than MK = 2.6, two-thirds of which showing significant near- or mid-IR excess emission. We present spectral energy distributions and extrapolated total luminosities for nine sources with large mid-infrared excesses that were measured in all four IRAC bands. For the brightest of these, G8540A, which is associated with a methanol maser and a compact HII region, we fitted a model of an infalling envelope plus disc plus central star to its observed 1.6 to 850 μm fluxes to get an idea of its physical properties. We also report a single 2.12 μm molecular hydrogen line emission knot near the centre of the cluster, which support the idea about an outflow activity. © 2010 ESO.Fil: Persi, P.. Istituto di Astrofisica Spaziale e Fisica Cosmica, Sezione di Roma; ItaliaFil: Tapia, M.. Universidad Nacional Autónoma de México; MéxicoFil: Gomez, Mercedes Nieves. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The XMM Newton and INTEGRAL observations of the supergiant fast X-ray transient IGR J16328-4726

The accretion mechanism producing the short flares observed from the Supergiant Fast X-ray Transients (SFXT) is still highly debated and forms a major part in our attempts to place these X-ray binaries in the wider context of the High Mass X-ray Binaries. We report on a 216 ks INTEGRAL observation of the SFXT IGR J16328-4726 (August 24-27, 2014) simultaneous with two fixed-time observations with XMM Newton (33ks and 20ks) performed around the putative periastron passage, in order to investigate the accretion regime and the wind properties during this orbital phase. During these observations, the source has shown luminosity variations, from 4x10^{34} erg/s to 10^{36} erg/s, linked to spectral properties changes. The soft X-ray continuum is well modeled by a power law with a photon index varying from 1.2 up to 1.7 and with high values of the column density in the range 2-4x10^{23}/cm^2. We report on the presence of iron lines at 6.8-7.1 keV suggesting that the X-ray flux is produced by accretion of matter from the companion wind characterized by density and temperature inhomogeneities

Near-infrared images of star forming regions containing masers. Las Campanas observations of 31 southern sources

We present sensitive high resolution near infrared (NIR) broad band (J, H, and K) observations of a sample of 31 Star Forming Regions (SFRs) which contain H_2O and OH maser sources. The observations are aimed at the detection and characterization of Young Stellar Objects (YSOs) which may be the source of excitation of the maser emission. In spite of the large number of sources detected in the regions, using positional coincidence and NIR colours we are able to reliably identify K-band sources related to the masing gas in a large fraction of the observed regions. The NIR infrared sources selected from close positional coincidence with the maser show strong NIR excesses and most probably represent the YSOs still embedded in their parental cocoon where the maser emission occurs

Herschel, Spitzer and Magellan infrared observations of the star-forming region RCW 121 (IRAS 17149−3916)

We present new deep near-infrared broad- and narrow-band imaging and low-resolution spec-troscopy of the star formation region RCW 121 (IRAS 17149−3916) which we analyse incombination withHerschel(70, 160, 250, 350 and 500μm) andSpitzer(3.6, 4.5, 5.8 and 8μm)images. The near-infrared photometry reveals the presence of a stellar cluster of approximatesize of 92 arcsec which is composed of at least 264 members, approximately 25 per cent ofthese showing excess emission atλ>2.0μm, indicative of circumstellar discs. Isochronescorresponding to ages 0.5–1.0 Myr andAV=7.8 fit well the position of a large fraction of likelycluster members in theKsversusH−Ksdiagram. We find three massive star-forming coreslocated in the boundaries of an expanding HIIregion ionized by a central O-type star. Fromtheir far-infrared spectral energy distributions (SEDs) we derive masses and temperatures ofthe dense cores. When these young stellar objects (YSOs) have warm emission components,the 1.2–500μm SEDs are fitted with Robitaille et al.’s star–disc-envelope model to obtain theirphysical parameters. The masses of the three YSOs are between 8 and 10 M . The youngestsite (core I) is undetected atλ<100μm and is at the earliest evolutionary stage that cancurrently be detected. The other two cores (II and III) contain YSOs of similar masses andhave near-infrared counterparts, which imply a more advanced evolutionary stage. The YSOat core II has been found to have associated a jet, with strong H2line emission, co-existingwith an H2O maser source. RCW 121 is another example of multiple star formation beingtriggered by the expansion of a single HIIregion.Fil: Tapia, M.. Universidad Nacional Autónoma de México; MéxicoFil: Persi, P.. Istituto Astrofisica e Planetologia Spaziale. Roma; ItaliaFil: Roth, Markus Albert. Las Campanas Observatory. La Serena; ChileFil: Elia, D.. Istituto Astrofisica e Planetologia Spaziale. Roma; ItaliaFil: Molinari, S.. Istituto Astrofisica e Planetologia Spaziale. Roma; ItaliaFil: Saldaño, Hugo Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Gomez, Mercedes Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentin

Young and very young stars in NGC 3372, the Carina nebula

Results are presented of a large-scale imaging photometric study of the stellar population in the northern part of NGC 3372 with a w avelength co verage from 0.33 to 2.5 µm. All observations were made at Las Campanas Observatory . The sizes of the three stellar clusters, Tr 14, Tr 15 and Tr 16, were determined b y means of star counts. Two-colour and colour-magnitude diagrams are presented and analyzed for eac h individual cluster. The three clusters were found to b e at a similar distance from the Sun, = 2.7 kpc, but with very large scatter in both AV and d. suggesting drastic variations in intracluster dust densit y . Dust particle size distribution variations are eviden t resulting in wide variations in extinction law. We determined ages bet ween 3 and 60 million years for Tr 15 and bet ween less than 1 and 6 million years for Tr 14 and Tr 16. The Tr 14 cluster is partially em bedded in a dense molecular cloud that extends to wards the south west reaching its highest densit y some three arcmin from the cluster nucleus. The ric h UV field created b y the Tr14 stars ionizes most of the visible HII region in its vicinit y and most of the radio HII region Car I. Deep J H K images of the Car I region reveal the presence of a young, em bedded stellar population that includes several O9–B0 stars and an ultracompact HII region.Se presentan los resultados de un estudio fotométrico de la población estelar en el norte de NGC 3372 en un intervalo espectral que cubre 0.33 a 2.5 µm. Las observaciones se llevaron a cabo en el Observatorio de Las Campanas. Se determinaron los tamaños de los tres cúmulos, Tr 14, Tr 15 y Tr 16, por medio de conteo de estrellas. Diagramas color-color y color-magnitud sugieren edades entre 3 y 60 millones de años para Tr 15 y entre menos de 1 y 6 millones de años para Tr 14 y Tr 16. Los tres cúmulos se encuentran a la misma distancia: = 2.7 kpc aunque con gran dispersión real en AV y en d. Tr 14 es un cúmulo que se encuentra parcialmente inmerso en una nube molecular densa que se extiende hacia el sureste, teniendo su máxima densidad a unos tres minutos de arco del núcleo del cúmulo. Casi todo el gas de la región HII es ionizado por las estrellas de Tr 14. Sin embargo, imágenes en J H K profundas revelan la presencia de una jo ven población de estrellas O y B inmersas en la nube, en donde se encuentra también una región HII ultracompacta.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

Young and very young stars in NGC 3372, the Carina nebula

Results are presented of a large-scale imaging photometric study of the stellar population in the northern part of NGC 3372 with a w avelength co verage from 0.33 to 2.5 µm. All observations were made at Las Campanas Observatory . The sizes of the three stellar clusters, Tr 14, Tr 15 and Tr 16, were determined b y means of star counts. Two-colour and colour-magnitude diagrams are presented and analyzed for eac h individual cluster. The three clusters were found to b e at a similar distance from the Sun, = 2.7 kpc, but with very large scatter in both AV and d. suggesting drastic variations in intracluster dust densit y . Dust particle size distribution variations are eviden t resulting in wide variations in extinction law. We determined ages bet ween 3 and 60 million years for Tr 15 and bet ween less than 1 and 6 million years for Tr 14 and Tr 16. The Tr 14 cluster is partially em bedded in a dense molecular cloud that extends to wards the south west reaching its highest densit y some three arcmin from the cluster nucleus. The ric h UV field created b y the Tr14 stars ionizes most of the visible HII region in its vicinit y and most of the radio HII region Car I. Deep J H K images of the Car I region reveal the presence of a young, em bedded stellar population that includes several O9–B0 stars and an ultracompact HII region.Se presentan los resultados de un estudio fotométrico de la población estelar en el norte de NGC 3372 en un intervalo espectral que cubre 0.33 a 2.5 µm. Las observaciones se llevaron a cabo en el Observatorio de Las Campanas. Se determinaron los tamaños de los tres cúmulos, Tr 14, Tr 15 y Tr 16, por medio de conteo de estrellas. Diagramas color-color y color-magnitud sugieren edades entre 3 y 60 millones de años para Tr 15 y entre menos de 1 y 6 millones de años para Tr 14 y Tr 16. Los tres cúmulos se encuentran a la misma distancia: = 2.7 kpc aunque con gran dispersión real en AV y en d. Tr 14 es un cúmulo que se encuentra parcialmente inmerso en una nube molecular densa que se extiende hacia el sureste, teniendo su máxima densidad a unos tres minutos de arco del núcleo del cúmulo. Casi todo el gas de la región HII es ionizado por las estrellas de Tr 14. Sin embargo, imágenes en J H K profundas revelan la presencia de una jo ven población de estrellas O y B inmersas en la nube, en donde se encuentra también una región HII ultracompacta.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica