scholarly journals The interstellar medium and star formation of galactic disks. I. Interstellar medium and giant molecular cloud properties with diffuse far-ultraviolet and cosmic-ray backgrounds

2018 ◽  
Vol 70 (SP2) ◽  
Author(s):  
Qi Li ◽  
Jonathan C Tan ◽  
Duncan Christie ◽  
Thomas G Bisbas ◽  
Benjamin Wu
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Molecular Cloud ◽  
Cosmic Ray ◽  
Galactic Disks ◽  
Cloud Properties ◽  
Giant Molecular Cloud ◽  
Far Ultraviolet

scholarly journals Using ages and kinematic traceback: the origin of young local associations

2008 ◽  
Vol 4 (S258) ◽  
pp. 123-132
Author(s):  
David Fernández ◽  
Francesca Figueras ◽  
Jordi Torra
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Molecular Cloud ◽  
Solar Neighbourhood ◽  
Recent History ◽  
Local Interstellar Medium ◽  
Local Bubble ◽  
Giant Molecular Cloud ◽  
History Of ◽  
The Impact

AbstractOver the last decade, several groups of young (mainly low-mass) stars have been discovered in the solar neighbourhood (closer than ~100pc), thanks to cross-correlation between X-ray, optical spectroscopy and kinematic data. These young local associations – including an important fraction whose members are Hipparcos stars – offer insights into the star formation process in low-density environments, shed light on the substellar domain, and could have played an important role in the recent history of the local interstellar medium. Ages estimates for these associations have been derived in the literature by several ways (HR diagram, spectra, Li and Hα widths, expansion motion, etc.). In this work we have studied the kinematic evolution of young local associations and their relation to other young stellar groups and structures in the local interstellar medium, thus casting new light on recent star formation processes in the solar neighbourhood. We compiled the data published in the literature for young local associations, including the astrometric data from the new Hipparcos reduction. Using a realistic Galactic potential we integrated the orbits for these associations and the Sco-Cen complex back in time. Combining these data with the spatial structure of the Local Bubble and the spiral structure of the Galaxy, we propose a recent history of star formation in the solar neighbourhood. We suggest that both the Sco-Cen complex and young local associations originated as a result of the impact of the inner spiral arm shock wave against a giant molecular cloud. The core of the giant molecular cloud formed the Sco-Cen complex, and some small cloudlets in a halo around the giant molecular cloud formed young local associations several million years later. We also propose a supernova in young local associations a few million years ago as the most likely candidate to have reheated the Local Bubble to its present temperature.

scholarly journals STAR FORMATION AND YOUNG STELLAR CONTENT IN THE W3 GIANT MOLECULAR CLOUD

2011 ◽  
Vol 743 (1) ◽  
pp. 39 ◽  
Author(s):  
Alana Rivera-Ingraham ◽  
Peter G. Martin ◽  
Danae Polychroni ◽  
Toby J. T. Moore
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Stellar Content ◽  
Giant Molecular Cloud

scholarly journals FOREST unbiased Galactic plane imaging survey with the Nobeyama 45 m telescope (FUGIN). VIII. Possible evidence of cloud–cloud collisions triggering high-mass star formation in the giant molecular cloud M 16 (Eagle Nebula)

2020 ◽  
Author(s):  
Atsushi Nishimura ◽  
Shinji Fujita ◽  
Mikito Kohno ◽  
Daichi Tsutsumi ◽  
Tetsuhiro Minamidani ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Velocity Structure ◽  
Galactic Plane ◽  
High Mass ◽  
Mass Star ◽  
Collision Event ◽  
Giant Molecular Cloud ◽  
Eagle Nebula ◽  
H Ii Region

Abstract M 16, the Eagle Nebula, is an outstanding H ii region which exhibits extensive high-mass star formation and hosts remarkable “pillars.” We herein obtained new 12COJ = 1–0 data for the region observed with NANTEN2, which were combined with the 12COJ = 1–0 data obtained using the FOREST unbiased galactic plane imaging with Nobeyama 45 m telescope (FUGIN) survey. These observations revealed that a giant molecular cloud (GMC) of ∼1.3 × 105 M⊙ is associated with M 16, which extends for 30 pc perpendicularly to the galactic plane, at a distance of 1.8 kpc. This GMC can be divided into the northern (N) cloud, the eastern (E) filament, the southeastern (SE) cloud, the southeastern (SE) filament, and the southern (S) cloud. We also found two velocity components (blueshifted and redshifted components) in the N cloud. The blueshifted component shows a ring-like structure, and the redshifted one coincides with the intensity depression of the ring-like structure. The position–velocity diagram of the components showed a V-shaped velocity feature. The spatial and velocity structures of the cloud indicated that two different velocity components collided with each other at a relative velocity of 11.6 km s−1. The timescale of the collision was estimated to be ∼4 × 105 yr. The collision event reasonably explains the formation of the O9V star ALS 15348, as well as the shape of the Spitzer bubble N19. A similar velocity structure was found in the SE cloud, which is associated with the O7.5V star HD 168504. In addition, the complementary distributions of the two velocity components found in the entire GMC suggested that the collision event occurred globally. On the basis of the above results, we herein propose a hypothesis that the collision between the two components occurred sequentially over the last several 106 yr and triggered the formation of O-type stars in the NGC 6611 cluster in M 16.

scholarly journals High Resolution X-ray Images of Puppis a and IC 443

1983 ◽  
Vol 101 ◽  
pp. 289-293
Author(s):  
R. Petre ◽  
C. R. Canizares ◽  
P. F. Winkler ◽  
F. D. Seward ◽  
R. Willingale ◽  
...  
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Molecular Cloud ◽  
Supernova Remnants ◽  
Surface Brightness ◽  
Middle Aged ◽  
X Ray ◽  
Giant Molecular Cloud

We present soft X-ray photomosaic images of two supernova remnants, Puppis A and IC 443, constructed from a series of exposures by the Einstein imaging instruments. The complex morphologies displayed in these images reflect the interaction between “middle-aged” supernova remnants and various components of the interstellar medium. Surface brightness variations across Puppis A suggest that inhomogeneities on scales from 0.2 to 30 pc are present in the interstellar medium, while the structure of IC 443 is apparently dominated by the interaction between the remnant and a giant molecular cloud.

Cold HI Gas in the M17SW Giant Molecular Cloud

1991 ◽  
Vol 9 (1) ◽  
pp. 146-147
Author(s):  
F. Sato ◽  
J. B. Whiteoak ◽  
R. E. Otrupcek ◽  
T. Tokushige
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Giant Molecular Cloud ◽  
Mean Size ◽  
Co Gas

AbstractThe cold HI cloud in the region of the M17SW giant molecular cloud comprises three major fragments with a mean size of ~ 30 pc. Their overall distribution is rather similar to that of CO gas, but one of the fragments does not seem to have a molecular counterpart. It is shown that such a cloud is also a future site of star formation.

scholarly journals The headlight cloud in NGC 628: An extreme giant molecular cloud in a typical galaxy disk

2020 ◽  
Vol 634 ◽  
pp. A121 ◽  
Author(s):  
Cinthya N. Herrera ◽  
Jérôme Pety ◽  
Annie Hughes ◽  
Sharon E. Meidt ◽  
Kathryn Kreckel ◽  
...  
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Large Scale ◽  
Stellar Population ◽  
High Mass ◽  
Molecular Gas ◽  
Giant Molecular Cloud ◽  
The Impact

Context. Cloud-scale surveys of molecular gas reveal the link between giant molecular cloud properties and star formation across a range of galactic environments. Cloud populations in galaxy disks are considered to be representative of the normal star formation process, while galaxy centers tend to harbor denser gas that exhibits more extreme star formation. At high resolution, however, molecular clouds with exceptional gas properties and star formation activity may also be observed in normal disk environments. In this paper we study the brightest cloud traced in CO(2–1) emission in the disk of nearby spiral galaxy NGC 628. Aims. We characterize the properties of the molecular and ionized gas that is spatially coincident with an extremely bright H II region in the context of the NGC 628 galactic environment. We investigate how feedback and large-scale processes influence the properties of the molecular gas in this region. Methods. High-resolution ALMA observations of CO(2–1) and CO(1−0) emission were used to characterize the mass and dynamical state of the “headlight” molecular cloud. The characteristics of this cloud are compared to the typical properties of molecular clouds in NGC 628. A simple large velocity gradient (LVG) analysis incorporating additional ALMA observations of 13CO(1−0), HCO+(1−0), and HCN(1−0) emission was used to constrain the beam-diluted density and temperature of the molecular gas. We analyzed the MUSE spectrum using Starburst99 to characterize the young stellar population associated with the H II region. Results. The unusually bright headlight cloud is massive (1 − 2 × 107 M⊙), with a beam-diluted density of nH2 = 5 × 104 cm−3 based on LVG modeling. It has a low virial parameter, suggesting that the CO emission associated with this cloud may be overluminous due to heating by the H II region. A young (2 − 4 Myr) stellar population with mass 3 × 105 M⊙ is associated. Conclusions. We argue that the headlight cloud is currently being destroyed by feedback from young massive stars. Due to the large mass of the cloud, this phase of the its evolution is long enough for the impact of feedback on the excitation of the gas to be observed. The high mass of the headlight cloud may be related to its location at a spiral co-rotation radius, where gas experiences reduced galactic shear compared to other regions of the disk and receives a sustained inflow of gas that can promote the mass growth of the cloud.

scholarly journals Star Formation Efficiencies at Giant Molecular Cloud Scales in the Molecular Disk of the Elliptical Galaxy NGC 5128 (Centaurus A)

2019 ◽  
Vol 887 (1) ◽  
pp. 88 ◽  
Author(s):  
D. Espada ◽  
S. Verley ◽  
R. E. Miura ◽  
F. P. Israel ◽  
C. Henkel ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Elliptical Galaxy ◽  
Giant Molecular Cloud ◽  
Centaurus A

scholarly journals Calibrating the relation of low-frequency radio continuum to star formation rate at 1 kpc scale with LOFAR

2019 ◽  
Vol 622 ◽  
pp. A8 ◽  
Author(s):  
V. Heesen ◽  
E. Buie II ◽  
C. J. Huff ◽  
L. A. Perez ◽  
J. G. Woolsey ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Low Frequency ◽  
Cosmic Ray ◽  
Radio Continuum ◽  
Gaussian Kernel ◽  
Spatially Resolved ◽  
Sky Survey ◽  
Inverse Compton ◽  
Far Ultraviolet

Context. Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free–free) emission. Aims. We calibrate the conversion from the spatially resolved 140 MHz RC emission to the SFR surface density (ΣSFR) at 1 kpc scale. Radio spectral indices give us, by means of spectral ageing, a handle on the transport of cosmic rays using the electrons as a proxy for GeV nuclei. Methods. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw-Frequency ARray (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio ΣSFR maps using the Condon relation. We compared these maps with hybrid ΣSFR maps from a combination of GALEX far-ultraviolet and Spitzer 24 μm data using plots tracing the relation at the highest angular resolution allowed by our data at 1.2 × 1.2 kpc2 resolution. Results. The RC emission is smoothed with respect to the hybrid ΣSFR owing to the transport of cosmic-ray electrons (CREs) away from star formation sites. This results in a sublinear relation (ΣSFR)RC ∝ [(ΣSFR)hyb]a, where a = 0.59 ± 0.13 (140 MHz) and a = 0.75 ± 0.10 (1365 MHz). Both relations have a scatter of σ = 0.3 dex. If we restrict ourselves to areas of young CREs (α >  −0.65; Iν ∝ να), the relation becomes almost linear at both frequencies with a ≈ 0.9 and a reduced scatter of σ = 0.2 dex. We then simulate the effect of CRE transport by convolving the hybrid ΣSFR maps with a Gaussian kernel until the RC–SFR relation is linearised; CRE transport lengths are l = 1–5 kpc. Solving the CRE diffusion equation, assuming dominance of the synchrotron and inverse-Compton losses, we find diffusion coefficients of D = (0.13–1.5)  × 1028 cm2 s−1 at 1 GeV. Conclusions. A RC–SFR relation at 1.4 GHz can be exploited to measure SFRs at redshift z ≈ 10 using 140 MHz observations.

The Collision of Giant Molecular Cloud with Galaxy: Hydrodynamics, Star Formation, Chemistry

2020 ◽  
pp. 261-267
Author(s):  
Igor Kulikov ◽  
Igor Chernykh ◽  
Dmitry Karavaev ◽  
Viktor Protasov ◽  
Vladimir Prigarin ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Giant Molecular Cloud
Sign in / Sign up

Export Citation Format

Share Document