Related papers: Atomic and molecular gas properties during cloud f…

Molecular clouds form from the atomic phase of the interstellar medium. However, characterizing the transition between the atomic and the molecular interstellar medium (ISM) is a difficult observational task. Here we address cloud formation…

Stars form in the dense interiors of molecular clouds. The dynamics and physical properties of the atomic interstellar medium (ISM) set the conditions under which molecular clouds and eventually stars will form. It is, therefore, critical…

We examine the triggering process of molecular cloud formation around diffuse HII regions. We calculate the time evolution of the shell as well as of the HII region in a two-phase neutral medium, solving the UV and FUV radiative transfer,…

We present synthetic Hi and CO observations of a simulation of decaying turbulence in the thermally bistable neutral medium. We first present the simulation, with clouds initially consisting of clustered clumps. Self-gravity causes these…

Cold atomic hydrogen clouds are the precursors of molecular clouds. Due to self-absorption, the opacity of cold atomic hydrogen may be high, and this gas may constitute an important mass component of the interstellar medium (ISM). Atomic…

Our understanding of how molecular clouds form in the interstellar medium (ISM) would be greatly helped if we had a reliable observational tracer of the gas flows responsible for forming the clouds. Fine structure emission from singly…

The presence of atomic gas mixed with molecular species in a "molecular" cloud may significantly affect its chemistry, the excitation of some species, and can serve as probe of the cloud's evolution. Cold neutral atomic hydrogen (HI) in…

The majority of hydrogen in the interstellar medium (ISM) is in atomic form. The transition from atoms to molecules and, in particular, the formation of the H$_2$ molecule, is a key step in cosmic structure formation en route to stars.…

The cold neutral medium (CNM) is where neutral atomic hydrogen (HI) is converted into molecular clouds, so the structure and kinematics of the CNM are key drivers of galaxy evolution. Here we provide new constraints on the vertical…

Atomic gas in the diffuse interstellar medium (ISM) is organized in filamentary structures. These structures usually host cold and dense molecular clumps. The Galactic magnetic field is considered to play an important role in the formation…

Context: Atomic and molecular cloud formation is a dynamical process. However, kinematic signatures of these processes are still observationally poorly constrained. Methods: Targeting the cloud-scale environment of the prototypical infrared…

We have mapped cold atomic gas in 21cm line HI self-absorption (HISA) at arcminute resolution over more than 90% of the Milky Way's disk. To probe the formation of H2 clouds, we have compared our HISA distribution with CO J=1-0 line…

We have investigated the possibility of molecular cloud formation via the Collision-induced Magnetic Reconnection (CMR) mechanism of the cold neutral medium (CNM). Two atomic gas clouds with conditions typical of the CNM were set to collide…

We present a steady-state analytical model for pressure-regulated formation of molecular clouds (MC) and stars (SF) in gaseous galactic disks and apply it to the Milky Way (MW). MC formation depends on midplane interstellar pressure…

We present the detection analysis of a diffuse molecular cloud at z$_{abs}$=2.4636 towards the quasar SDSS J1513+0352(z$_{em}\,\simeq$ 2.68) observed with the X-shooter spectrograph(VLT). We measure very high column densities of atomic and…

Context. It is almost banal to say that the interstellar medium (ISM) is structurally and thermodynamically complex. But the variety of the governing processes, including stellar feedback, renders the investigation challenging. High…

We have complemented existing observations of HI absorption with new observations of HCO$^+$, C$_2$H, HCN, and HNC absorption from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Northern Extended Millimeter Array (NOEMA) in…

{It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding…

We present the first localized detections of the cold neutral medium (CNM) in IC10, offering a rare view of dense atomic gas in a low-metallicity (0.27 solar metallicity) dwarf galaxy. As a low-metallicity starburst, IC10's interstellar…

Molecular hydrogen clouds are a key component of the interstellar medium because they are the birthplaces for stars. They are embedded in atomic gas that pervades the interstellar space. However, the details of how molecular clouds assemble…