Cygnus Rift Research Articles

The Multilayer Nature of Molecular Gas toward the Cygnus Region

We study the physical properties and 3D distribution of molecular clouds (MCs) toward the Cygnus region using the MWISP CO survey and Gaia DR3 data. Based on Gaussian decomposition and clustering for 13CO lines, over 70% of the fluxes are recovered. With the identification result of 13CO structures, two models are designed to measure the distances of the molecular gas in velocity crowding regions. The distances of more than 200 large 13CO structures are obtained toward the 150 deg2 region. Additionally, tens of the identified MC structures coincide well with masers and/or intense mid-IR emission. We find multiple gas layers toward the region: (1) the extensive gas structures composing the Cygnus Rift from 700 pc to 1 kpc across the whole region; (2) the ∼1.3 kpc gas layer mainly in the Cygnus X South region; and (3) the 1.5 kpc dense filament at the Cygnus X North region and many cometary clouds shaped by Cygnus OB2. We also note that the spatial distribution of young stellar object candidates is generally consistent with the molecular gas structures. The total molecular mass of the Cygnus region is estimated to be ∼2.7 × 106 M ⊙ assuming an X-factor ratio XCO=2×1020cm−2(Kkms−1)−1 . The foreground Cygnus Rift contributes ∼25% of the molecular mass in the whole region. Our work presents a new 3D view of the MCs' distribution toward the Cygnus X region, as well as the exact molecular gas mass distribution in the foreground Cygnus Rift.

Open Cluster IC 1369 and Its Vicinity: Multicolor Photometry and Gaia DR2 Astrometry

Abstract The open cluster IC 1369, located in Cygnus close to the galactic equator at the 89.°6 longitude, and its vicinity are investigated by applying two-dimensional photometric classification of stars down to V = 19 mag measured in the Vilnius seven-color photometric system. Employing the Gaia DR2 coordinates, parallaxes, and proper motions, 143 cluster members are found having cluster membership probabilities ≥0.75. The hottest stars of the evolved main sequence are of spectral class B9. Distances to the cluster, determined by two methods based on the Gaia parallaxes, are 3280 and 3370 pc with an uncertainty of 400–500 pc. Employing the physical HR diagram with the coordinates versus and the Padova isochrones, the cluster age is found to be between 300 and 350 Myr. Among the cluster members we identified six red giants of spectral classes G5–G8 and luminosities II–III, 17 Am stars, one Ap star, and one B5 blue straggler. The extinction shows a steep rise up to ∼2.0 mag at 300–700 pc, caused by the extensions of the dust cloud LDN 970 and the Great Cygnus Rift, and up to ∼2.5 mag at the edge of the Perseus arm at 3.0 kpc. The extinction is almost constant between 0.9 and 2.5 kpc from the Sun. The average extinction of the cluster members is 2.54 mag. A systematic error of color excesses found in the Argonaut calculator results is discussed.

Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc

Gaiastellar measurements are currently revolutionizing our knowledge of the evolutionary history of the Milky Way. 3D maps of the interstellar dust provide complementary information and are a tool for a wide range of uses. We built 3D maps of the dust in the Local arm and surrounding regions. To do so,GaiaDR2 photometric data were combined with 2MASS measurements to derive extinction toward stars that possess accurate photometry and relative uncertainties on DR2 parallaxes smaller than 20%. We applied a new hierarchical inversion algorithm to the individual extinctions that is adapted to large datasets and to an inhomogeneous target distribution. Each step associates regularized Bayesian inversions in all radial directions and a subsequent inversion in 3D of all their results. Each inverted distribution serves as a prior for the subsequent step, and the spatial resolution is progressively increased. We present the resulting 3D distribution of the dust in a 6 × 6 × 0.8 kpc3volume around the Sun. Its main features are found to be elongated along different directions that vary from below to above the mid-plane. The outer part of Carina-Sagittarius, mainly located above the mid-plane, the Local arm/Cygnus Rift around and above the mid-plane, and the fragmented Perseus arm are oriented close to the direction of circular motion. The spur of more than 2 kpc length (nicknamed thesplit) that extends between the Local Arm and Carina-Sagittarius, the compact near side of Carina-Sagittarius, and the Cygnus Rift below the Plane are oriented along l ~40 to 55°. Dust density images in vertical planes reveal a wavy pattern in some regions and show that the solar neighborhood within ~500 pc remains atypical by its extent above and below the Plane. We show several comparisons with the locations of molecular clouds, HII regions, O stars, and masers. The link between the dust concentration and these tracers is markedly different from one region to the other.

Young open cluster IC 4996 and its vicinity: multicolor photometry and Gaia DR2 astrometry

The open cluster IC 4996 in Cygnus and its vicinity are investigated by applying a two-dimensional photometric classification of stars measured in the Vilnius seven-color photometric system. Cluster members are identified by applying distances based on the Gaia DR2 parallaxes and the point vector diagram of the Gaia DR2 proper motions. For some B-type stars, spectroscopic MK types are also obtained from the Asiago spectra and collected from the literature. New parameters of the cluster are derived. The interstellar extinction AV covers a wide range of values, from 1.3 to 2.4 mag; the mean value in the central part of the cluster is 1.8 mag. The cluster distance is 1915 ± 110 pc, and its age is within 8–10 Myr. The cluster exhibits a long sequence from early-B to G stars, where stars cooler than B8 are in the pre-main-sequence stage. The plot of extinction versus distance shows a steep rise of AV up to 1.6 mag at 700–800 pc, which is probably related to dust clouds at the edge of the Great Cygnus Rift. The next increase in extinction by an additional 0.8 mag at d ≥ 1.7 kpc is probably related to the associations Cyg OB1 and Cyg OB3. The cluster IC 4996 does not belong to the Cyg OB1 association, which is located closer to the Sun, at 1682 ± 116 pc. It seems likely that the cluster and the surrounding O-B stars have a common origin with the nearby association Cyg OB3 since Gaia data show that these stellar groups are located at a similar distance.

INTERSTELLAR EXTINCTION IN THE DIRECTION OF THE OPEN CLUSTER M29

The interstellar extinction is investigated in a 1.5 deg2 area in the direction of the open cluster M29 (NGC 6913) in Cygnus, centered at R.A. = 20h 24m, decl. = +38° 30′. The study is based on photometric classification of 1110 stars in spectral and luminosity classes down to V = 19 mag using photometry in the Vilnius seven-color system published in Paper I (Milasius et al. 2013). Additionally, in the same area the extinction is investigated using 1147 red clump giants (RCGs), identified by combining selected two-color diagrams of the 2MASS and Spitzer surveys. The investigated area is divided into three parts with different obscuration and in these directions the extinction versus distance plots up to 5 kpc are presented. In the whole area a steep rise of the extinction is observed at a distance of ∼800 pc; it should be related to dust clouds in the Great Cygnus Rift obscuring the stars behind it by AV = 4.0–4.7 mag. RCGs exhibit much larger extinction values, up to = 1.2–1.3 mag in the more transparent areas and 1.45 mag in the northeastern part of the area and above it, where the dust cloud TGU H466 is located. These values of correspond to AV = 10–12 mag. We do not exclude the possibility that the largest values of the extinction belong not to RCGs but to some contaminating intrinsically red AGB stars penetrated through the applied RCG selection constraints. The extinction in the TGU H466 cloud probably originates in two cloud systems—the Great Cygnus Rift at 800 pc and the Cygnus X complex of dust and molecular clouds at 1.3–1.5 kpc.

THE ENIGMA OF THE OPEN CLUSTER M29 (NGC 6913) SOLVED

Determining the distance to the open cluster M29 (NGC 6913) has proven difficult, with distances determined by various authors differing by a factor of two or more. To solve this problem, we have initiated a new photometric investigation of the cluster in the Vilnius seven-color photometric system supplementing it with available data in the BV and JHK_s photometric systems, and spectra of the nine brightest stars of spectral classes O and B. Photometric spectral classes and luminosities of 260 stars in a 15 arcmin x 15 arcmin area down to V = 19 mag are used to investigate the interstellar extinction run with distance and to estimate the distance of the Great Cygnus Rift, 800 pc. The interstellar reddening law in the optical and near-infrared regions is found to be close to normal, with the ratio of extinction to color excess R(BV) = 2.87. The extinction A(V) of cluster members is between 2.5 to 3.8 mag, with a mean value of 2.97 mag or E(B-V) = 1.03. The average distance of eight stars of spectral types O9-B2 is 1.54 +- 0.15 kpc. Two stars from the seven brightest ones are field stars: HDE 229238 is a background B0.5 supergiant and HD 194378 is a foreground F star. In the intrinsic color-magnitude diagram, seven fainter stars of spectral classes B3-B8 are identified as possible members of the cluster. The 15 selected members of the cluster of spectral classes O9--B8 plotted on the log L/L(sun) vs. log T(eff) diagram, together with the isochrones from the Padova database, give the age of the cluster as 5 +- 1 Myr.

The JCMT12CO(3–2) survey of the Cygnus X region

Cygnus X is one of the most complex areas in the sky. This complicates interpretation, but also creates the opportunity to investigate accretion into molecular clouds and many subsequent stages of star formation, all within one small field of view. Understanding large complexes like Cygnus X is the key to understanding the dominant role that massive star complexes play in galaxies across the Universe. The main goal of this study is to establish feasibility of a high-resolution CO survey of the entire Cygnus X region by observing part of it as a Pathfinder, and to evaluate the survey as a tool for investigating the star-formation process. A 2x4 degree area of the Cygnus X region has been mapped in the 12CO(3-2) line at an angular resolution of 15" and a velocity resolution of ~0.4km/s using HARP-B and ACSIS on the James Clerk Maxwell Telescope. The star formation process is heavily connected to the life-cycle of the molecular material in the interstellar medium. The high critical density of the 12CO(3-2) transition reveals clouds in key stages of molecule formation, and shows processes that turn a molecular cloud into a star. We observed ~15% of Cygnus X, and demonstrated that a full survey would be feasible and rewarding. We detected three distinct layers of 12CO(3-2) emission, related to the Cygnus Rift (500-800 pc), to W75N (1-1.8 kpc), and to DR21 (1.5-2.5 kpc). Within the Cygnus Rift, HI self-absorption features are tightly correlated with faint diffuse CO emission, while HISA features in the DR21 layer are mostly unrelated to any CO emission. 47 molecular outflows were detected in the Pathfinder, 27 of them previously unknown. Sequentially triggered star formation is a widespread phenomenon.

A multiwavelength study of the S106 region

Context. The distance to the wellknown bipolar nebula S106 and its associated molecular cloud is highly uncertain. Values between 0.5 and 2 kpc are given in the literature, favoring a view of S106 as an isolated object at a distance of 600 pc as part of the “Great Cygnus Rift”. However, there is evidence that S106 is physically associated with the Cygnus X complex at a distance of ∼1.7 kpc (Schneider et al. 2006, A&A, 458, 855). In this case, S106 is a more massive and more luminous star forming site than previously thought. Aims. We aim to understand the large-scale distribution of molecular gas in the S106 region, its possible association with other clouds in the Cygnus X south region, and the impact of UV radiation on the gas. This will constrain the distance to S106. Methods. We employ a part of an extended 13 CO and C 18 O1 → 0 survey, performed with the FCRAO, and data from the MSX and Spitzer satellites to study the spatial distribution and correlation of molecular cloud/PDR interfaces in Cygnus X south. The 2MASS survey is used to obtain a stellar density map of the region. Results. We find evidence that several molecular clouds including S106 are directly shaped by the UV radiation from members of several Cygnus OB clusters, mainly NGC 6913, and are thus located at a distance of ∼1.7 kpc in the Cygnus X complex. The definition of OB associations in terms of spatial extent and stellar content in the Cygnus X south region is revised.

An extremely high velocity multipolar outflow around IRAS 20050 + 2720

view Abstract Citations (50) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Extremely High Velocity Multipolar Outflow around IRAS 20050+2720 Bachiller, R. ; Fuente, A. ; Tafalla, M. Abstract We report high angular resolution maps in the CO 2 approaches 1 and CS 3 approaches 2 lines of the molecular gas around the embedded object IRAS 20050+2027. This is a 260 solar luminosity source located in the Cygnus Rift at 700 pc from the Sun. The CS data uncover a dense core of size 0.3 pc and 80 solar mass centered on the IRAS object. The CO map reveals a remarkable molecular outflow consisting of three pairs of lobes emanating from the close vicinity of the IRAS source. One of the lobe pairs is a highly collimated jet of extremely high velocity emission (LSR velocities up to +/- 70 km/s) containing molecular 'bullets'. We briefly examine different possibilties to explain the complex structure of the multipolar outflow. A single outflow appears unable to explain all the CO observations, so we suggest that two or three independent outflows emanate form different young sources embedded within the core. Publication: The Astrophysical Journal Pub Date: May 1995 DOI: 10.1086/187887 Bibcode: 1995ApJ...445L..51B Keywords: Astronomical Spectroscopy; Emission Spectra; Infrared Astronomy; Interstellar Matter; Line Spectra; Molecular Flow; Molecular Gases; Spectrum Analysis; Star Formation; Cygnus Constellation; High Resolution; Infrared Astronomy Satellite; Radiation Sources; Radio Spectra; Stellar Luminosity; Astrophysics; ISM: JETS AND OUTFLOWS; ISM: INDIVIDUAL ALPHANUMERIC: IRAS 20050; 2027; ISM: MOLECULES; RADIO LINES: ISM; STARS: FORMATION full text sources ADS | data products SIMBAD (15)

CO and OH absorption toward the low-latitude radio source 2023+336

We report interferometric observations of (12)CO (0 to 1) 115 GHz and OH 1667 MHz absorption toward the extragalactic radio continuum source 2023+336. Our data show two partially blended absorption features near +2 km/s LSR which probably originate in local molecular clouds in the Cygnus rift, approximately 0.7 kpc away. The CO lines are optically thin, with tau(sub CO) = 0.5 +/- 0.1, while tau(sub OH) = 0.030 +/- 0.004. The detected absorption features have a combined velocity width of 3.0 km/s FWHM, greater than the width of the corresponding (12)CO emission features, Full Width of Half Maximum (FWHM) = 2.3 km/s, indicating that the absorbing gas in a approximately 1 AU diameter column shows a greater velocity range than the gas in the 0.2 pc diameter emission beam. CO excitation temperatures T(sub ex), range from 2.7 to 7.0 K across the line profile, implying that the gas along this line of sight is rotationally quite cold. By measuring the (12)CO excitation temperature and optical depth, we derive an abundance ratio, (CO)/(H2), of 6 x 10(exp -6), which is more than an order of magnitude lower than is seen elsewhere. Our low observed CO optical depth is inconsistent with the ratio of (12)CO to (13)CO emission line integrals, 16:1, which implies that the (12)CO is optically thick. As a solution to these anomalies, we propose that the CO absorption and emission arise from preferentially different parts of the molecular medium. Other solutions would require an anomalous (12)CO/(13)CO abundance ratio and an anomalous CO/H2 abundance ratio, or much lower excitation temperatures. Since we find no absorption at negative velocities with tau greater than 0.23 (2.5 sigma), there is no compelling evidence for the existence of an extensive population of cold molecular gas in the outer Galaxy along this line of sight.