[Abridged] The interstellar medium is observed to be organised in filamentary structures, as well as neutral (HI) and ionized (HII) bubbles. The expanding nature of these bubbles makes them shape their surroundings and possibly play a role in the formation and evolution of interstellar filaments. We present APEX $^{13}$CO and C$^{18}$O(2-1) observations of the NGC 6334 molecular cloud. We investigate the gas velocity structure along and across the 50 pc-long cloud and towards 75 identified velocity-coherent-filaments (VCFs). We measure a wealth of velocity gradients along the VCFs. We derive the column density and velocity power spectra of the VCFs. These power spectra are well represented with power laws showing similar slopes for both quantities (with a mean of about -2), albeit some differ by up to a factor of two. The position velocity diagrams perpendicular to three VCFs show the V-shaped velocity pattern, corresponding to a bent structure in velocity space with the filament at the tip of the V surrounded by an extended structure connected to it with a velocity gradient. This velocity structure is qualitatively similar to that resulting from numerical simulations of filament formation from large-scale compression from propagating shock fronts. In addition, the radial profiles perpendicular to these VCFs hint to small-scale internal impacts from neighbouring HII bubbles. The observed opposite curvature in velocity space towards the VCFs points to various origins of large-scale external compressions from propagating HI bubbles. This suggests the plausible importance of multiple HI compressions, separated in space and time, in the formation and evolution of molecular clouds and their star formation history. These latter atomic compressions due to past and distant star formation events are complemented by the impact of HII bubbles from present time and local star formation activity.
We have produced for the first time a detailed velocity map of the giant filamentary nebula surrounding NGC 1275, the Perseus cluster's brightest galaxy, and revealed a previously unknown rich velocity structure across the entire nebula. We present new observations of the low-velocity component of this nebula with the optical imaging Fourier transform spectrometer SITELLE at CFHT. With its wide field of view ($\sim$11'$\times$11'), SITELLE is the only integral field unit spectroscopy instrument able to cover the 80 kpc$\times$55 kpc (3.8'$\times$2.6') large nebula in NGC 1275. Our analysis of …
We present Atacama Large Millimeter/submillimeter Array (ALMA) and Karl G. Jansky Very Large Array (JVLA) observations of the massive infrared dark cloud NGC 6334S (also known as IRDC G350.56+0.44), located at the southwestern end of the NGC 6334 molecular cloud complex. The H$^{13}$CO$^{+}$ and the NH$_{2}$D lines covered by the ALMA observations at a $\sim$3$^{\prime\prime}$ angular resolution ($\sim$0.02 pc) reveal that the spatially unresolved non-thermal motions are predominantly subsonic and transonic, a condition analogous to that found in low-mass star-forming molecular clouds. The obs…
In this paper, we report the peculiar HI morphology of the cluster spiral galaxy NGC 6145, which has a 150 kpc HI filament on one side that is nearly parallel to its major axis. This filament is made up of several HI clouds and the diffuse HI gas between them, with no optical counterparts. We compare its HI distribution with other one-sided HI distributions in the literature, and find that the overall HI distribution is very different from the typical tidal and ram-pressure stripped HI shape, and its morphology is inconsistent with being a pure accretion event. Only about 30% of the total HI g…
TRAO Survey of Nearby Filamentary Molecular clouds, the Universal Nursery of Stars (TRAO-FUNS). III. Filaments and dense cores in the NGC 2068 and NGC 2071 regions of Orion B
We revisit the filamentary structures of galaxies around the Virgo cluster, exploiting a larger dataset based on the HyperLeda database than previous studies. In particular, this includes a large number of low-luminosity galaxies, resulting in better sampled individual structures. We confirm seven known structures in the distance range 4~$h^{-1}$~Mpc~$<$ SGY~$<$ 16~$h^{-1}$ Mpc, now identified as filaments, where SGY is the axis of the supergalactic coordinate system roughly along the line of sight. The Hubble diagram of the filament galaxies suggests they are infalling toward the main-body of…
We report the serendipitous young Large Magellanic Cloud cluster, NGC 1971, exhibits an extended main-sequence turnoff (eMSTO) possibly originated by mostly a real age spread. We used CT1 Washington photometry to produce a colour-magnitude diagram (CMD) with the fiducial cluster features. From its eMSTO, we estimated an age spread of ~ 170 Myr (observed age range 100-280 Myr), once observational errors, stellar binarity, overall metalicity variations and stellar rotation effects were subtracted in quadrature from the observed age width.
We present results from multi-frequency polarization-sensitive Very Large Array observations of the Seyfert-starburst composite galaxy NGC3079. Our sensitive radio observations reveal a plethora of radio filaments comprising the radio lobes in this galaxy. We analyze the origin of these radio filaments in the context of existing Chandra X-ray and HST emission-line data. We do not find a one-to-one correlation of the radio filaments with the emission line filaments. The north-eastern lobe is highly polarized with polarization fractions $\sim$33% at 5 GHz. The magnetic fields are aligned with th…
We present results of $^{12}$CO(J = 1-0) imaging observations of NGC 4567/4568, a galaxy pair in a close encounter, with Atacama Large Millimetre/submillimetre Array. For the first time, we find clear evidence of a molecular collision front whose velocity dispersion is 16.8$\pm$1.4 km s$^{-1}$ at the overlapping region owing to high spatial and velocity resolution. By integrating over the velocity width that corresponds to the molecular collision front, we find a long filamentary structure with a size of 1800 pc $\times$ 350 pc at the collision front. This filamentary molecular structure spati…
High-spectral-resolution Observations of the [S II] Emission-line Doublet in the Filamentary Nebula Surrounding NGC 1275
Université de Montréal（蒙特利尔大学）；Centre de recherche en astrophysique du Québec (CRAQ)（魁北克天体物理研究中心）；Dragonfly Focused Research Organization（Dragonfly专注研究机构）；Leibniz-Institut für Astrophysik Potsdam（波茨坦莱布尼茨天体物理研究所）；Columbia University（哥伦比亚大学）；Center for Computational Astrophysics, Flatiron Institute（平顿研究所计算天体物理学中心）；Michigan State University（密歇根州立大学）；Durham University（杜伦大学）；University of Cambridge（剑桥大学）
We identify structures of the young star cluster NGC 2232 in the solar neighborhood (323.0 pc), and a newly discovered star cluster LP 2439 (289.1 pc). Member candidates are identified using the Gaia DR2 sky position, parallax and proper motion data, by an unsupervised machine learning method, \textsc{StarGO}. Member contamination from the Galactic disk is further removed using the color magnitude diagram. The four identified groups (NGC 2232, LP 2439 and two filamentary structures) of stars are coeval with an age of 25 Myr and were likely formed in the same giant molecular cloud. We correct t…
High nitrogen abundance is characteristic of Type I planetary nebulae as well as their highly filamentary structure. In the present work we test the hypothesis of shocks as a relevant excitation mechanism for a Type-I nebula, NGC 6302, using recently released diagnostic diagrams to distinguish shocks from photoexcitation. The construction of diagrams depends on emission line ratios and kinematical information. NGC 6302 shows the relevance of shocks in peripheral regions and the importance to the whole nebula. Using shocks, we question the usual assumption of ICF calculation, justifying a warni…
We report on the magnitude of the intrinsic [Fe/H] spread in the Small Magellanic Cloud (SMC) intermediate-age massive clusters NGC 339, 361, Lindsay 1 and 113, respectively. In order to measure the cluster metallicity dispersions, we used accurate Stromgren photometry of carefully selected cluster red giant branch (RGB) stars. We determined the Fe-abundance spreads by employing a maximum likelihood approach. The spreads obtained using the more accurate photometry of the brighter RGB stars resulted to be marginal (~ 0.05+-0.03 dex) for NGC 339 and NGC 361, while for Lindsay 1 and Lindsay 113 w…
Filamentary Network and Magnetic Field Structures Revealed with BISTRO in the High-Mass Star-Forming Region NGC2264 : Global Properties and Local Magnetogravitational Configurations
Several recent studies have shown that the Vela OB2 region hosts a complex constellation of sub-populations with ages in the range 10 to 50 Myr. Such populations might represent the best example of the outcome of clustered star formation in Giant Molecular clouds (GMC). We use Gaia DR2 data over an area of 40 deg radius around the open cluster Collinder 135 to extend the study of the stellar populations of the Vela OB2 region over an area of several hundreds of parsecs on sky. Detailed clustering algorithms combined with the exquisite astrometric quality of the GAIA catalogue allow us to detec…
NGC 6369是一种双壳PN，具有一个透明外壳或包膜和微弱的双极延伸。我们已经使用了地面和空间的窄带光学和近红外图像，宽带中红外图像，光学长缝阶梯光谱，和中红外光谱来研究它的物理结构。这些观测结果证实了NGC 6369内壳的双极结构，但它们也揭示了H2和强多环芳烃（PAH）从位于明亮内壳外的分子内含物的光解离区域（PDR）发射的证据。
We present a UV study of 3 extended UV (XUV) galaxies that we have observed with the UVIT and the GMRT. XUV galaxies show filamentary or diffuse star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX observations found that surprisingly 30% of all the nearby spiral galaxies have XUV disks. The XUV galaxies can be broadly classified as type 1 and type 2 XUV disks. The type 1 XUV disks have star formation that is linked to that in their main disk, and the UV emission appears as extended, filamentary spiral arms…
Dark mammoth trunks in the merging galaxy NGC 1316 and a mechanism of cosmic double helices
NGC 1316是一个巨大的椭圆星系，包含复杂的黑暗尘埃网络。这些特征的形态已经使用哈勃太空望远镜的高级巡天照相机图像进行了详细的检查。结果发现，大部分的功能是由长的细丝。此外，还存在着大量的暗结构，从灯丝向内突出。这些结构中的许多结构与银河系H II区域的象鼻惊人地相似，尽管要大得多。这种结构被称为猛犸象的躯干，通常是直立的，形状通常类似于字母V或Y。在一些猛犸象的躯干中，Y的茎可以分解成两个或更多的细丝，其中许多细丝显示出相互缠绕的迹象。一个模型的猛犸象的鼻子，有关最近的理论大象的鼻子，提出。基于磁化细丝，该模型能够解释所观察到的猛犸象躯干的各种形状，包括躯干结构。
The internal dynamics of multiple stellar populations in Globular Clusters (GCs) provides unique constraints on the physical processes responsible for their formation. Specifically, the present-day kinematics of cluster stars, such as rotation and velocity-dispersion, could be related to the initial configuration of the system. In recent work, we provided the first study of the kinematics of different stellar populations in NGC$\,$0104 over a large field of view in the plane of the sky, exploiting Gaia Data Release 2 (DR2) proper motions combined with multi-band ground-based photometry. In thi…
The star formation history of the Large Magellanic Cloud star clusters NGC1846 and NGC1783
NGC 1846和NGC 1783是位于大麦云星云中的两个大质量星团，它们同时拥有一个扩展的主序星关闭区和一个红巨星双团。它们的质量相似，但主要在角的大小上不同。从F435W、F555W和F814W滤波器中的高质量ACS数据和更新的恒星演化轨迹集出发，利用经典的CMD重建方法，得到了它们的恒星形成率与年龄的函数SFR（t）。该方法证实了从以前的分析相同的数据得出的恒星形成的延长期。当分析进行了一个更好的分辨率在年龄，我们发现了明确的证据，50万年长的间隙之间的最古老的高峰在SFR（t），第二个长期的恒星形成，在两个集群。对于更紧凑的星系团NGC1846，星系团中心的SFR（t）和半径在20到60角秒之间的环（从4.8到15.4秒差距）似乎没有显著的差异。同样的情况并没有发生在更扩展的NGC1783星系团中，发现外环（在33到107弧秒之间，从8.0到25.9秒差距）比中心稍年轻。我们还探讨了目前的质量函数和二进制分数的最佳拟合斜率为不同的集群区域，发现在NGC1783的中心和外环之间的质量函数不同的提示。这些研究结果进行了讨论，在目前的情况下，形成集群与多个关闭。
We present H13CO+ (J=1-0) and HNC (J=1-0) maps of regions in Serpens South, Serpens Main and NGC 1333 containing filaments. We also observe the Serpens regions using H13CN (J=1-0). These dense gas tracer molecular line observations carried out with CARMA have an angular resolution of ~7", a spectral resolution of ~0.16 km/s and a sensitivity of 50-100 mJy/beam. Although the large scale structure compares well with the Herschel dust continuum maps, we resolve finer structure within the filaments identified by Herschel. The H13CO+ emission distribution agrees with the existing CARMA N2H+ (J=1-0)…
The metal-rich and old bulge globular cluster (GC) NGC 6388 is one of the most massive Galactic GCs (M ~ 10^6 Msun). However, the spectroscopic properties of its multiple stellar populations rested only on 32 red giants (only seven of which observed with UVES, the remaining with GIRAFFE), given the difficulties in observing a rather distant cluster, heavily contaminated by bulge and disc field stars. We bypassed the problem using the largest telescope facility ever: the European Southern Observatory (ESO) archive. By selecting member stars identified by other programmes, we derive atmospheric …
We present the result of a detailed analysis of HST UV and optical deep images of the massive and young (~1.5 Gyr) stellar cluster NGC 1783 in the Large Magellanic Cloud. This system does not show evidences of multiple populations (MPs) along the red giant branch (RGB) stars. However, we find that the cluster main-sequence (MS) shows evidence of a significant broadening (50% larger than what is expected from photometric errors) along with hints of possible bimodality in the MP sensitive (F343N - F438W, F438W) color-magnitude-diagram (CMD). Such an effect is observed in all color combinations i…
We revealed the detailed structure of a vastly extended H$α$-emitting nebula ("H$α$ nebula") surrounding the starburst/merging galaxy NGC 6240 by deep narrow-band imaging observations with the Subaru Suprime-Cam. The extent of the nebula is $\sim$90 kpc in diameter and the total H$α$ luminosity amounts to $\approx 1.6 \times 10^{42}$ erg s$^{-1}$. The volume filling factor and the mass of the warm ionized gas are $\sim$10$^{-4}$--10$^{-5}$ and $\sim$$5 \times 10^8$ $M_\odot$, respectively. The nebula has a complicated structure, which includes numerous filaments, loops, bubbles, and knots. We …
Chemical hints of Population III stars from silicon abundances in massive galaxies
Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉古纳大学）；Leiden Observatory（莱顿天文台）；Swinburne University（斯威本科技大学）；INAF-Osservatorio Astronomico di Capodimonte（意大利国家天体物理研究所卡波迪蒙特天文台）
Charge exchange emission is known to provide a key diagnostic to the interface between hot and cold matter in many astrophysical environments. Most of the recent charge exchange studies focus on its emission in the X-ray band, but few on the UV part, although the latter can also provide a powerful probe of the charge exchange process. An atomic calculation, as well as an application to observed data, are presented to explore and describe the potential use of the UV data for the study of cosmic charge exchange. Using the newest charge exchange model in the SPEX code v3.03, we re-analyze an arch…
JWST reveals how black holes are fed: kiloparsec-scale multiphase filaments feed sub-kiloparsec circumnuclear disks
Université de Montréal（蒙特利尔大学）；University of Michigan（密歇根大学）；Princeton University（普林斯顿大学）；Michigan State University（密歇根州立大学）；Institut Trottier de recherche sur les exoplanètes（特鲁瓦耶系外行星研究所）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）；University of Portsmouth（朴茨茅斯大学）
We used a data set from AKARI and Herschel images at wavelengths from 7 $μ$m to 500 $μ$m to catch the evidence of dust processing in galactic winds in NGC 1569. Images show a diffuse infrared (IR) emission extending from the galactic disk into the halo region. The most prominent filamentary structure seen in the diffuse IR emission is spatially in good agreement with the western H$α$ filament (western arm). The spatial distribution of the $F_\mathrm{350}/F_\mathrm{500}$ map shows high values in regions around the super-star clusters (SSCs) and towards the western arm, which are not found in th…
The structure and kinematics of gaseous, disk-halo interfaces are imprinted with the processes that transfer mass, metals, and energy between galactic disks and their environments. We study the extraplanar diffuse ionized gas (eDIG) layer in the interacting, star-forming galaxy NGC 5775 to better understand the consequences of star-formation feedback on the dynamical state of the thick-disk interstellar medium (ISM). Combining emission-line spectroscopy from the Robert Stobie Spectrograph on the Southern African Large Telescope with radio continuum observations from Continuum Halos in Nearby G…
We present a detailed study of the Magellanic irregular galaxy NGC 4449 based on both archival and new photometric data from the Legacy Extragalactic UV Survey, obtained with the Hubble Space Telescope Advanced Camera for Surveys and Wide Field Camera 3. Thanks to its proximity ($D=3.82\pm 0.27$ Mpc) we reach stars 3 magnitudes fainter than the tip of the red giant branch in the F814W filter. The recovered star formation history spans the whole Hubble time, but due to the age-metallicity degeneracy of the red giant branch stars, it is robust only over the lookback time reached by our photometr…
