The distribution of water in the high-mass star-forming region NGC 6334I
M. Emprechtinger, D. C. Lis, T. Bell, T. G. Phillips, P. Schilke, C. Comito, R. Rolffs, F. van der Tak, C. Ceccarelli, H. Aarts, A. Bacmann, A. Baudry, M. Bened… 展开作者
M. Emprechtinger, D. C. Lis, T. Bell, T. G. Phillips, P. Schilke, C. Comito, R. Rolffs, F. van der Tak, C. Ceccarelli, H. Aarts, A. Bacmann, A. Baudry, M. Benedettini, E. A. Bergin, G. Blake, A. Boogert, S. Bottinelli, S. Cabrit, P. Caselli, A. Castets, E. Caux, J. Cernicharo, C. Codella, A. Coutens, N. Crimier, K. Demyk, C. Dominik, P. Encrenaz, E. Falgarone, A. Fuente, M. Gerin, P. Goldsmith, F. Helmich, P. Hennebelle, T. Henning, E. Herbst, P. Hily-Blant, T. Jacq, C. Kahane, M. Kama, A. Klotz, J. Kooi, W. Langer, B. Lefloch, A. Loose, S. Lord, A. Lorenzani, S. Maret, G. Melnick, D. Neufeld, B. Nisini, V. Ossenkopf, S. Pacheco, L. Pagani, B. Parise, J. Pearson, C. Risacher, M. Salez, P. Saraceno, K. Schuster, J. Stutzki, X. Tielens, M. van der Wiel, C. Vastel, S. Viti, V. Wakelam, A. Walters, F. Wyrowski, H. Yorke
We present observations of twelve rotational transitions of H2O-16, H2O-18, and H2O-17 toward the massive star-forming region NGC 6334 I, carried out with Herschel/HIFI as part of the guaranteed time key program Chemical HErschel Surveys of Star forming regions (CHESS). We analyze these observations to obtain insights into physical processes in this region.
We identify three main gas components (hot core, cold foreground, and outflow) in NGC 6334 I and derive the physical conditions in these components.
The hot core, identified by the emission in highly excited lines, shows a high excitation temperature of 200 K, whereas water in the foreground component is predominantly in the ortho- and para- ground states. The abundance of water varies between 4 10^-5 (outflow) and 10^-8 (cold foreground gas). This variation is most likely due to the freeze-out of water molecules onto dust grains. The H2O-18/H2O-17 abundance ratio is 3.2, which is consistent with the O-18/O-17 ratio determined from CO isotopologues. The ortho/para ratio in water appears to be relatively low 1.6(1) in the cold, quiescent gas, but close to the equilibrium value of three in the warmer outflow material (2.5(0.8)).
The Survey of Water and Ammonia in Nearby galaxies (SWAN) studies atomic and molecular species across the nuclei of four star forming galaxies: NGC\,253, IC\,342, NGC\,6946, and NGC\,2146. As part of this survey, we present Karl G. Jansky Very Large Array (VLA) molecular line observations of three galaxies: IC\,342, NGC\,6946 and NGC\,2146. NGC\,253 is covered in a previous paper. These galaxies were chosen to span an order of magnitude in star formation rates and to select a variety of galaxy types. We target the metastable transitions of ammonia NH$_{3}$(1,1) to (5,5), the 22\,GHz water (H$_…
The star-forming regions (SFRs) in the peculiar galaxies NGC 660, NGC 1512, NGC 4395 and NGC 4618 are studied. The relationships between such characteristics of star forming regions as UV, nearand far-IR fluxes, as well as in the Halpha and HI lines, surface brightness in these ranges, and the scatter of the radial velocities of ionized and neutral hydrogen are considered. It is shown that in all the galaxies considered, the IR fluxes from SFRs are less than in the "normal" galaxies, but for different reasons: in the galaxies with signs of recent interaction NGC 660 and NGC 1512, this is due t…
We report the results of a sensitive search for water maser emission in the Local Group Galaxy NGC 6822 with the Karl G. Jansky Very Large Array. The observations provide tentative single-epoch detections of four candidates, associated with two infrared-bright star formation regions (Hubble I/III and Hubble IV). The candidate maser detections are all offset from the velocity range where strong emission from HI neutral gas is observed toward NGC 6822, with the closest offset by 40 kms$^{-1}$. Our observations include the location of NL1K, a previous tentative water maser detection in NGC 6822. …
We analyze parameters of the interstellar matter emission in star-forming complexes in the high metallicity galaxies NGC~628, NGC~2976, and NGC~3351, which have different morphological types. The relation between H$α$ emission and emission in CO and HI lines is considered along with the relation between H$α$ emission and dust emission in the infrared range (IR). The fluxes and surface brightnesses in the UV and IR correlate well with H$α$ emission. The HI emission also correlates well with H$α$, while the correlation between the CO and H$α$ emission is much less prominent. The ratio of the flu…
We present new molecular gas maps of NGC5195 (alternatively known as M51b) from the Combined Array for Research in Millimeter Astronomy (CARMA), including 12CO(1-0), 13CO(1-0), CN(1-0), and CS(2-1). NGC5195 has also been detected in 3mm continuum. NGC5195 has a 12CO/13CO ratio consistent with normal star-forming galaxies. The CN(1-0) intensity is higher than is seen in an average star-forming galaxy, possibly enhanced in the diffuse photo-dissociation regions. Stellar template fitting of the nuclear spectrum of NGC5195 shows two stellar populations: an 80% mass fraction of old (>10Gyr) and a 2…
We present a comparative study of CO and polycyclic aromatic hydrocarbon (PAH) emission toward a region including the massive star-forming regions of NGC 6334 and NGC 6357. We use the NANTEN $^{12}$CO($J$ = 1--0) data and the $AKARI$ 9 $μ$m All-Sky diffuse map in order to evaluate the calibration accuracy of the $AKARI$ data. We confirm that the overall CO distribution shows a good spatial correspondence with the PAH emission, and their intensities exhibit a good power-law correlation with a spatial resolution down to 4$'$ over the region of 10$^\circ$$\times$10$^\circ$. We also reveal poorer …
Galaxies with polar rings consist of two subsystems, a disk and a ring, which rotate almost in orthogonal planes. In this paper, we analyze the parameters characterizing the composition of the interstellar medium and star formation in star-forming complexes, belonging to a polar ring galaxy NGC660. We show that star-forming regions in the ring of the galaxy are distinctively different from those in the galaxy disk. They possess substantially lower infrared luminosities, indicative of less dust mass in these regions than in a typical disk star-forming region. UV and H$α$ luminosities also appea…
We present Very Large Array observations of the 7_0-6_1 A^+ methanol maser transition at 44 GHz towards NGC 6334F, G8.67-0.36, and M17. These arcsecond resolution observations complete a previous, larger VLA survey of this maser transition in high-mass star-forming regions reported by Kurtz et al. We confirm the presence of 44 GHz methanol maser emission in all three sources, detecting eight distinct maser components in NGC 6334F, twelve components in G8.67-0.36 and one in M17.
The NGC 2024 FIR 6 region was observed in the water maser line at 22 GHz and the methanol class I maser lines at 44, 95, and 133 GHz. The water maser spectra displayed several velocity components and month-scale time variabilities. Most of the velocity components may be associated with FIR 6n, while one component was associated with FIR 4. A typical life time of the water-maser velocity-components is about 8 months. The components showed velocity fluctuations with a typical drift rate of about 0.01 km/s/day. The methanol class I masers were detected toward FIR 6. The methanol emission is confi…
We present Karl G Jansky Very Large Array molecular line observations of the nearby starburst galaxy NGC 253, from SWAN: "Survey of Water and Ammonia in Nearby galaxies". SWAN is a molecular line survey at centimeter wavelengths designed to reveal the physical conditions of star forming gas over a range of star forming galaxies. NGC 253 has been observed in four 1GHz bands from 21 to 36 GHz at 6" ($\sim100$pc) spatial and 3.5 km s$^{-1}$ spectral resolution. In total we detect 19 transitions from seven molecular and atomic species. We have targeted the metastable inversion transitions of ammon…
Aim: The aim of this work is to search Seyfert 2 galaxy NGC 4945, a well-known 22 GHz water megamaser galaxy, for water (mega)maser emission at 183 GHz. Method: We used APEX SEPIA Band 5 to perform the observations. Results: We detected 183 GHz water maser emission towards NGC 4945 with a peak flux density of ~3 Jy near the galactic systemic velocity. The emission spans a velocity range of several hundred km/s. We estimate an isotropic luminosity of > 1000 Lsun, classifying the emission as a megamaser. A comparison of the 183 GHz spectrum with that observed at 22 GHz suggests that 183 GHz emis…
We present a far-UV (FUV) study of the star-forming complexes (SFCs) in three nearby galaxies using the Ultraviolet Imaging Telescope (UVIT). The galaxies are close to face-on and show significant outer disk star formation. Two of them are isolated (NGC 628, NGC 6946), and one is interacting with distant companions (NGC 5457). We compared the properties of the SFCs inside and outside the optical radius (R$_{25}$). We estimated the sizes, star formation rates (SFRs), metallicities, and the Toomre Q parameter of the SFCs. We find that the outer disk SFCs are at least ten times smaller in area th…
We present Herschel/HIFI observations of 30 transitions of water isotopologues toward the high-mass star forming region NGC 6334 I. The line profiles of H_2^{16}O, H_2^{17}O, H_2^{18}O, and HDO show a complex pattern of emission and absorption components associated with the embedded hot cores, a lower-density envelope, two outflow components, and several foreground clouds, some associated with the NGC 6334 complex, others seen in projection against the strong continuum background of the source. Our analysis reveals an H2O ortho/para ratio of 3 +/- 0.5 in the foreground clouds, as well as the o…
We present a study of complexes of young massive star clusters (YMCs), embedded in extragalactic giant HII regions, based on the coupling of spectroscopic with photometric and spectrophotometric observations of about 100 star forming regions in seven spiral galaxies (NGC 628, NGC 783, NGC 2336, NGC 6217, NGC 6946, NGC 7331, and NGC 7678). The complete observational database has been observed and accumulated within the framework of our comprehensive study of extragalactic star forming regions. The current paper presents the last part of either unpublished or refreshed photometric and spectropho…
We present the results of unbiased 22 GHz H2O water and 44 GHz class I CH3OH methanol maser surveys in the central 7x10 arcmin area of NGC 1333 and two additional mapping observations of a 22 GHz water maser in a ~3x3arcmin area of the IRAS4A region. In the 22 GHz water maser survey of NGC 1333 with sensitivity of sigma~0.3Jy, we confirmed masers toward H2O(B) in the region of HH 7-11 and IRAS4B. We also detected new water masers at ~20arcsec away in the western direction of IRAS4B or ~25arcsec away in the southern direction of IRAS4A. We could not however find young stellar objects or molecul…
We discuss integral field spectra of the compact star-forming complex that is the brightest near-infrared (NIR) source in the central regions of the starburst galaxy NGC 253. The spectra cover the H and K passbands and were recorded with the Gemini NIR Spectrograph during sub-arcsec seeing conditions. Absorption features in the spectrum of the star-forming complex are weaker than in the surroundings. An absorption feature is found near 1.78um that coincides with the location of a C2 bandhead. Emission lines of Brgamma, [FeII], and HeI2.06um do not track the NIR continuum light. Pockets of star…
Secular and environmental effects play a significant role in regulating the star formation rate and hence the evolution of the galaxies. Since UV flux is a direct tracer of the star formation in galaxies, the UltraViolet Imaging Telescope (UVIT) onboard ASTROSAT enables us to characterize the star forming regions in a galaxy with its remarkable spatial resolution. In this study, we focus on the secular evolution of NGC 628, a spiral galaxy in the local universe. We exploit the resolution of UVIT to resolve up to $\sim$ 63 pc in NGC 628 for identification and characterization of the star formin…
Long slit spectra recorded with GMOS on Gemini South are used to examine the star-forming history of the lenticular galaxy NGC 5102. Structural and supplemental photometric information are obtained from archival Spitzer [3.6] images. Comparisons with model spectra point to luminosity-weighted metallicities that are consistent with the colors of resolved red giant branch stars in the disk. The nucleus has a luminosity-weighted age at visible wavelengths of ~1 Gyr, and the integrated light is dominated by stars that formed over a time period of only a few hundred Myr. For comparison, the luminos…
We present new maser emission from ^{14}NH_3 (9,6) in NGC 7538. Our observations include the known spectral features near v_LSR = -60 km/s and -57 km/s and several more features extending to -46 km/s. In three epochs of observation spanning two months we do not detect any variability in the ammonia masers, in contrast to the >10-fold variability observed in other ^{14}NH_3 (9,6) masers in the Galaxy over comparable timescales. We also present observations of water masers in all three epochs for which emission is observed over the velocity range -105 km/s < v_LSR < -4 km/s, including the highes…
We investigate the stellar and ionized gas kinematics, and stellar populations of NGC3182 galaxy using integral field spectrograph data from the Calar Alto Legacy Integral Field Area survey. We try to clarify the nature of the ring structure in NGC 3182. We find a negative stellar age gradient out to the ring, while [α/Fe] considerably enhanced in the ring. The stellar metallicity shows a smooth negative gradient. From the line ratio diagnostic diagrams, we confirm that NGC 3182 is a Seyfert galaxy from emission line flux ratio, while the gas in the inner ring is ionized mostly by young stars.…
We present the results of our study of starforming regions in the lenticular galaxy NGC 4324. During a complex analysis of multiwavelength observational data -- the narrow-band emission-line images obtained with the 2.5-m telescope at the Caucasus Mountain Observatory of the Sternberg Astronomical Institute of the Moscow State University and the archival images in the broad bands of the SDSS, GALEX and WISE surveys -- we have detected young starforming complexes (clumps) located in the inner ring of the lenticular galaxy NGC 4324, and we have established a regular pattern of their distribution…
We present a far-UV (FUV) and near-UV (NUV) imaging study of recent star formation in the nearby spiral galaxy NGC 2336 using the Ultraviolet Imaging Telescope (UVIT). NGC 2336 is nearly face-on in morphology and has a multi-armed, branching spiral structure which is associated with star forming regions distributed mainly along the spiral arms and the co-rotation ring around the bar. We have identified 72 star forming knots in the disk, of which only two are in the inter-arm regions and 6 in the co-rotation ring. We have tabulated their positions and estimated their luminosities, sizes, star f…
A giant molecular cloud has been detected surrounding the supernebula in NGC 5253, revealing details of the formation and feedback process in a very massive star cluster. "Cloud D" was recently mapped in CO J=3-2 with the Submillimeter Array. The cloud surrounds a currently forming massive cluster of mass ~10$^6$ $\rm M_\odot$ and luminosity ~10$^9$ $\rm L_\odot$. Cloud D is hot, clearly associated with the cluster, yet kinematically relatively quiescent. The dust mass is ~15,000 $\rm M_\odot$, giving a gas-to-dust ratio of ~50, nearly an order of magnitude lower than expected for this low met…
We present the results of observations of 22GHz H2O maser emission in NGC 6240 and M51 made with the Karl G. Jansky Very Large Array. Two major H2O maser features and several minor features are detected toward the southern nucleus of NGC 6240. These features are redshifted by about 300 km/s from the galaxy's systemic velocity and remain unresolved at the synthesized beam size. A combination of our two-epoch observations and published data reveals an apparent correlation between the strength of the maser and the 22GHz radio continuum emission, implying that the maser excitation relates to the a…
Context. Ionization plays a central role in the gas-phase chemistry of molecular clouds. Since ions are coupled with magnetic fields, which can in turn counteract gravitational collapse, it is of paramount importance to measure their abundance in star-forming regions. Aims. We use spectral line observations of the high-mass star-forming region NGC 6334 I to derive the abundance of two of the most abundant molecular ions, HCO+ and N2H+, and consequently, the cosmic ray ionization rate. In addition, the line profiles provide information about the kinematics of this region. Methods. We present hi…
In recent years, Circumnuclear Star Forming Regions (CNSFRs) have been studied in different frequencies and telescopes, diverse studies about connection between nuclear activity and star formation in the CNSFRs were doing using optical data, IFS and models. We obtain data of the Seyfert 2 galaxy NGC 1068 at J band between 1.35-1.32$μ$ using the 8.1m Gemini telescope and GNIRS IFU mode. We found the radial velocity and intensity maps for [FeII]$λ$12570, Pa$β$ $λ$12814 and FeII $λ$13201 lines of all the components. The gas emission has a double origin associated with photoionization by young sta…
We present observational results of water vapor maser emission with our high-sensitivity 22 GHz VLBI imaging of the Seyfert galaxy NGC 1068. In this galaxy, there are the following four nuclear radio sources; NE, C, S1, and S2. Among them, the S1 component has been identified as the nucleus while the C component has been considered as attributed to the radio jet. In our VLBI observation, we find the following two types of the water maser emission at the S1 component. One is the linearly aligned component that is considered as an edge-on disk with the inner radius of 0.62 pc. The dynamical mass…
Aims. The aim of this paper is to study deuterated water in the solar-type protostars NGC1333 IRAS4A and IRAS4B, to compare their HDO abundance distribution with other star-forming regions, and to constrain their HDO/H2O ratios. Methods. Using the Herschel/HIFI instrument as well as ground-based telescopes, we observed several HDO lines covering a large excitation range (Eup/k=22-168 K) towards these protostars and an outflow position. Non-LTE radiative transfer codes were then used to determine the HDO abundance profiles in these sources. Results. The HDO fundamental line profiles show a very…
In this work we analyse the structure of a subspace of the phase space of the star-forming region NGC~ 2264 using the Spectrum of Kinematic Groupings (SKG). We show that the SKG can be used to process a collection of star data to find substructure at different scales. We have found structure associated with the NGC~ 2264 region and also with the background area. In the NGC~ 2264 region, a hierarchical analysis shows substructure compatible with that found in previous specific studies of the area but with an objective, compact methodology that allows us to homogeneously compare the structure of…
We performed J- and R-band linear polarimetry with the 4.2 m William Herschel Telescope at the Observatorio del Roque de los Muchachos and with the 1.6 m telescope at the Observatório do Pico dos Dias, respectively, to derive the magnetic field geometry of the diffuse molecular cloud surrounding the embedded protostellar system NGC 1333 IRAS 4A. We obtained interstellar polarization data for about two dozen stars. The distribution of polarization position angles has low dispersion and suggests the existence of an ordered magnetic field component at physical scales larger than the protostar. So…
We present an 8 pc x 5 pc resolution view of the central ~ 200 pc region of the nearby starburst galaxy NGC 253, based on ALMA Band 7 (λ ~ 0.85 mm or ν ~ 350 GHz) observations covering 11 GHz. We resolve the nuclear starburst of NGC 253 into eight dusty star-forming clumps, 10 pc in scale, for the first time. These clumps, each of which contains (4-10) x 10^4 M_sun of dust (assuming that the dust temperature is 25 K) and up to 6 x 10^2 massive (O5V) stars, appear to be aligned in two parallel ridges, while they have been blended in previous studies. Despite the similarities in sizes and dust m…
We discuss the nature of a discrete, compact radio source (NGC 4725 B) located $\approx$1.9 kpc from the nucleus in the nearby star-forming galaxy NGC 4725, which we believe to be a new detection of extragalactic Anomalous Microwave Emission (AME). Based on detections at 3, 15, 22, 33, and 44 GHz, NGC 4725 B is a $μ$Jy radio source peaking at $\approx$33 GHz. While the source is not identified in $BVRI$ photometry, we detect counterparts in the mid-infrared $Spitzer$/IRAC bands (3.6, 4.5, 5.8, 8.0 $μ$m) that appear to be associated with dust emission in the central region of NGC 4725. Conseque…
The halos of disk galaxies form a crucial connection between the galaxy disk and the intergalactic medium. Massive stars, HII regions, or dwarf galaxies located in the halos of galaxies are potential tracers of recent accretion and/or outflows of gas, and are additional contributors to the photon field and the gas phase metallicity. We investigate the nature and origin of a star-forming dwarf galaxy candidate located in the halo of the edge-on Virgo galaxy NGC 4634 with a projected distance of 1.4 kpc and a H$α$ star formation rate of $\sim 4.7 \times 10^{-3} \text{M}_\odot \text{yr}^{-1}$ in …
We present a detailed stellar clustering analysis with the application of the two-point correlation function on distinct young stellar ensembles. Our aim is to understand how stellar systems are assembled at the earliest stages of their formation. Our object of interest is the star-forming region NGC 346 in the Small Magellanic Cloud. It is a young stellar system well-revealed from its natal environment, comprising complete samples of pre--main-sequence and upper main-sequence stars, very close to their formation. We apply a comprehensive characterization of the autocorrelation function for bo…
Star formation in galaxies is a hierarchical process with a wide range of scales from smaller clusters to larger stellar complexes. Here, we present an ultra-violet imaging study of the nearby flocculent spiral galaxy NGC 7793, observed with the Ultra-Violet Imaging Telescope (UVIT). We find that the disk scale-length estimated in Far-UV (2.64$\pm$0.16 kpc) is larger than that in Near-UV (2.21$\pm$0.21 kpc) and optical (1.08 kpc), which supports the inside-out growth scenario of the galaxy disk. The star-forming UV disk is also found to be contained within the extent of H~I gas of column densi…
Groups are the most common association of galaxies in the Universe, found in different configuration states such as loose, compact and fossil groups. We have studied the galaxy group MKW 4s, dominated by the giant early-type galaxy NGC 4104 at z=0.0282. Our aim was to understand the evolutionary stage of this group and to place it within the framework of the standard LambdaCDM cosmological scenario. We have obtained deep optical data with CFHT/Megacam (g and r bands) and we have applied both the galfit 2D image fitting program and the IRAF/ellipse 1D radial method to model the brightest group …
We present the results of second epoch ALMA observations of 321 GHz H$_2$O emission toward two nearby active galactic nuclei, NGC 4945 and the Circinus galaxy, together with Tidbinbilla 70-m monitoring of their 22 GHz H$_2$O masers. The two epoch ALMA observations show that the strengths of the 321 GHz emission are variable by a factor of at least a few, confirming a maser origin. In the second epoch, 321 GHz maser emission from NGC 4945 was not detected, while for the Circinus galaxy the flux density significantly increased and the velocity gradient and dispersion have been measured. With the…
We examine the relation between polycyclic aromatic hydrocarbon (PAH) emission at 8 microns and far-infrared emission from hot dust grains at 24 microns and from large dust grains at 160 and 250 microns in the nearby spiral galaxies NGC 2403 and M83 using data from the Spitzer Space Telescope and Herschel Space Observatory. We find that the PAH emission in NGC 2403 is better correlated with emission at 250 microns from dust heated by the diffuse interstellar radiation field (ISRF) and that the 8/250 micron surface brightness ratio is well-correlated with the stellar surface brightness as measu…
Some post-merger galaxies are known to undergo a starburst phase that quickly depletes the gas reservoir and turns it into a red-sequence galaxy, though the details are still unclear. Here we explore the pattern of recent star formation in the central region of the post-merger galaxy NGC7252 using high resolution UV images from the UVIT on ASTROSAT. The UVIT images with 1.2 and 1.4 arcsec resolution in the FUV and NUV are used to construct a FUV-NUV colour map of the central region. The FUV-NUV pixel colour map for this canonical post-merger galaxy reveals a blue circumnuclear ring of diameter…
Magnetic fields in the massive star-forming region NGC 6334 and their relationship with the properties of dust filaments probed by [CII] and PAH emissions
通过近红外偏振和 [CII] 线观测，发现 NGC 6334 主纤维的磁场垂直于纤维，气体沿磁场从 HII 区壳层吸积，促进活跃恒星形成。
Although deuterium enrichment of water may provide an essential piece of information in the understanding of the formation of comets and protoplanetary systems, only a few studies up to now have aimed at deriving the HDO/H2O ratio in low-mass star forming regions. Previous studies of the molecular deuteration toward the solar-type class 0 protostar, IRAS 16293-2422, have shown that the D/H ratio of water is significantly lower than other grain-surface-formed molecules. It is not clear if this property is general or particular to this source. In order to see if the results toward IRAS 16293-242…
We investigate the distribution of the gas (ionized, neutral atomic and molecular), and interstellar dust in the complex star forming region NGC6357 with the goal of studying the interplay between the massive stars in the open cluster Pis24 and the surrounding interstellar matter. Our study of the distribution of the ionized gas is based on narrow-band Hhalfa, [SII], and [OIII] images obtained with the Curtis-Schmidt Camera at CTIO, Chile, and on radio continuum observations at 1465 MHz taken with the VLA with a synthesized beam of 40 arcsec. The distribution of the molecular gas is analyzed u…
In contrast to extensively studied dense star-forming cores, little is known about diffuse gas surrounding star-forming regions. We study molecular gas in the high-mass star-forming region NGC6334I, which contains diffuse, quiescent components that are inconspicuous in widely used molecular tracers such as CO. We present Herschel/HIFI observations of CH toward NGC6334I observed as part of the CHESS key program. HIFI resolves the hyperfine components of its J=3/2-1/2 transition, observed in both emission and absorption. The CH emission appears close to the systemic velocity of NGC6334I, while i…
We studied 102 star forming regions in seven spiral galaxies (NGC 628, NGC 783, NGC 2336, NGC 6217, NGC 6946, NGC 7331, and NGC 7678) on the basis of complex spectroscopic, photometric (UBVRI) and spectrophotometric (H alpha line) observations. Using data on the chemical composition and absorption in HII regions, obtained from spectroscopic observations, and using evolutionary models, we estimated physical parameters (ages and masses) of young stellar groupings embedded in HII regions. We found that the gas extinction, A(gas), which determined from the Balmer decrement, does not correspond in …
Are the initial conditions for clustered star formation the same as for non-clustered star formation? To investigate the initial gas properties in young proto-clusters we carried out a comprehensive and high-sensitivity study of the internal structure, density, temperature, and kinematics of the dense gas content of the NGC1333 region in Perseus, one of the nearest and best studied embedded clusters. The analysis of the gas velocities in the Position-Position-Velocity space reveals an intricate underlying gas organization both in space and velocity. We identified a total of 14 velocity-coheren…
From an observational point of view, the role of magnetic fields in star formation remains unclear, and two main theoretical scenarios have been proposed so far to regulate the star-formation processes. The first model assumes that turbulence in star-forming clumps plays a crucial role, and especially that protostellar outflow-driven turbulence is crucial to support cluster-forming clumps; while the second scenario is based on the consideration of a magnetically-supported clump. Previous studies of the NGC 2264-C protocluster indicate that, in addition to thermal pressure, some extra support m…
Spectra that cover wavelengths from 0.6 to 1.1um are used to examine the behavior of emission and absorption features in a contiguous 22 x 300 arcsec region centered on the nearby dwarf galaxy NGC 55. Based on the relative strengths of various emission features measured over spatial scales of many tens of parsecs, it is concluded that the ionization states and sulphur abundances in most of the star-forming regions near the center of NGC 55 are similar. A large star-forming region is identified in the north west part of the disk at a projected distance of ~1 kpc from the galaxy center that has …
We present Submillimeter Array (SMA) observations at 345 GHz towards the intermediate/high-mass cluster-forming region NGC 6334 V. From the dust emission we spatially resolve three dense condensations, the brightest one presenting the typical chemistry of a hot core. The magnetic field (derived from the dust polarized emission) shows a bimodal converging pattern towards the hot core. The molecular emission traces two filamentary structures at two different velocities, separated by 2 km/s, converging to the hot core and following the magnetic field distribution. We compare the velocity field an…
We report low frequency observations of Wolf-Rayet galaxies, NGC 4214 and NGC 4449 at 610, 325 and 150 MHz, using the Giant Meterwave Radio Telescope (GMRT). We detect diffuse extended emission from NGC 4214 at and NGC 4449. NGC 4449 is observed to be five times more radio luminous than NGC 4214, indicating vigorous star formation. We estimate synchrotron spectral index after separating the thermal free-free emission and obtain $α_{nt}=-0.63\pm0.04$ (S$\proptoν^{α_{nt}}$) for NGC 4214 and $-0.49\pm0.02$ for NGC 4449. About $22\%$ of the total radio emission from NGC 4214 and $\sim 9\%$ from NG…
Understanding the history and evolution of small bodies, such as dust grains and comets, in planet-forming disks is very important to reveal the architectural laws responsible for the creation of planetary systems. These small bodies in cold regions of the disks are typically considered as mixtures of dust particles with molecular ices, where ices cover the surface of a dust core or are actually physically mixed with dust. Whilst the first case, ice-on-dust, has been intensively studied in the laboratory in recent decades, the second case, ice-mixed-with-dust, present uncharted territory. This…
We present centimeter and millimeter observations of the NGC 2071 star-forming region performed with the VLA and CARMA. We detected counterparts at 3.6 cm and 3 mm for the previously known sources IRS 1, IRS 2, IRS 3, and VLA 1. All these sources show SEDs dominated by free-free thermal emission at cm wavelengths, and thermal dust emission at mm wavelengths, suggesting that all of them are associated with YSOs. IRS 1 shows a complex morphology at 3.6 cm, with changes in the direction of its elongation. We discuss two possible explanations to this morphology: the result of changes in the direct…
`Water In Star-forming regions with Herschel' (WISH) is a key program on the Herschel Space Observatory designed to probe the physical and chemical structure of young stellar objects using water and related molecules and to follow the water abundance from collapsing clouds to planet-forming disks. About 80 sources are targeted covering a wide range of luminosities and evolutionary stages, from cold pre-stellar cores to warm protostellar envelopes and outflows to disks around young stars. Both the HIFI and PACS instruments are used to observe a variety of lines of H2O, H218O and chemically rela…
We present new Gemini/GMOS spectroscopic and archival imaging data of the interacting galaxy NGC 92, which is part of a compact group and displays an extended tidal tail. We have studied the physical properties of 20 star-forming complexes in this system. We found that the star-forming regions located in the tidal tail of NGC 92 have ages younger than 8 Myr, which suggests that these objects were formed in situ. The spectroscopic data reveals that these regions have slightly sub-solar metallicities, suggesting that they were formed from pre-enriched material. Using the oxygen abundances derive…
We present analyses of the spatial distributions of stars in the young (1 - 3 Myr) star-forming regions IC348 and NGC1333 in the Perseus Giant Molecular Cloud. We quantify the spatial structure using the $\mathcal{Q}$-parameter and find that both IC348 and NGC1333 are smooth and centrally concentrated with $\mathcal{Q}$-parameters of 0.98 and 0.89 respectively. Neither region exhibits mass segregation ($Λ_{\rm MSR} = 1.1^{+0.2}_{-0.3}$ for IC348 and $Λ_{\rm MSR} = 1.2^{+0.4}_{-0.3}$ for NGC1333, where $Λ_{\rm MSR} \sim 1$ corresponds to no mass segregation), nor do the most massive stars resid…
