Related papers: Ground-state ammonia and water in absorption towar…
Circumstellar envelopes (CSEs) of a variety of evolved stars have been found to contain ammonia (NH3) in amounts that exceed predictions from conventional chemical models by many orders of magnitude. The observations reported here were…
We have carried out a sensitive high-latitude (|b| > 15deg.) HI 21cm-line absorption survey towards 102 sources using the GMRT. With a 3-sigma detection limit in optical depth of ~0.01, this is the most sensitive HI absorption survey. We…
Based on measurements with the Effelsberg 100-m telescope, a multi-line study of molecular species is presented toward the gravitational lens system PKS1830-211. Obtaining average radial velocities and performing Large Velocity Gradient…
With a goal toward deriving the physical conditions in external galaxies, we present a study of the ammonia (NH$_3$) emission and absorption in a sample of star forming systems. Using the unique sensitivities to kinetic temperature afforded…
We searched for absorption lines of highly ionized O and Ne in the energy spectra of two Low-mass X-ray binaries, 4U1820-303 in the globular cluster NGC6624 and Cyg X-2, observed with the Chandra LETG, and detected O VII, O VIII and Ne IX…
We present results of an extensive mapping survey of N2H+(1-0) in about 60 low mass cloud cores already mapped in the NH3(1,1) inversion transition line. The survey has been carried out at the FCRAO antenna with an angular resolution about…
The FU Orionis star V883 Ori provides a unique opportunity to probe the water snowline in a protoplanetary disk. During an accretion burst, the enhanced stellar luminosity heats the disk, sublimating ices and bringing volatile species into…
Using archival data, we have made an HI absorption study of the 7$^\prime$ halo surrounding the Sgr A complex, observed towards the Galactic centre (GC) region. We find strong HI absorption near velocities of $-$53 km s$^{-1}$, which is due…
Models of pure gas-phase chemistry in well-shielded regions of molecular clouds predict relatively high levels of molecular oxygen, O2, and water, H2O. Contrary to expectation, the space missions SWAS and Odin found only very small amounts…
The interstellar region within the few central parsecs around the super-massive black hole, Sgr A* at the very Galactic center is composed by a number of overlapping molecular structures which are subject to one of the most hostile physical…
A high latitude HI 21 cm-line absorption survey toward extragalactic sources was recently completed using the Giant Meterwave Radio Telescope (GMRT). A total of 104 sources with mod(b) > 15 deg. and with a 21 cm flux density greater than 1…
We report the detection of the ground state rotational emission of ammonia, ortho-NH$_3$ $(J_K=1_0\rightarrow0_0)$ in a gravitationally lensed, intrinsically hyperluminous, star-bursting galaxy at $z=2.6$. The integrated line profile is…
We present ISO observations of several H2 pure-rotational lines (from S(0) to S(5)) towards a sample of 16 molecular clouds distributed along the central ~ 500 pc of the Galaxy. We also present C18O and 13CO J=1->0 and J=2->1 observations…
Sgr B2 is a well-known star forming molecular cloud complex in the Galactic center region showing evidence of high energy activity as traced by the K$\alpha$ neutral FeI line at 6.4 keV, as well as GeV and TeV $\gamma$-ray emission. Here we…
Mon R2, at a distance of 830 pc, is the only ultracompact HII region (UC HII) where the photon-dominated region (PDR) between the ionized gas and the molecular cloud can be resolved with Herschel. HIFI observations of the abundant compounds…
Nitrogen chemistry in protoplanetary disks and the freeze-out on dust particles is key to understand the formation of nitrogen bearing species in early solar system analogs. So far, ammonia has not been detected beyond the snowline in…
We model the temperature and chemical structure of molecular clouds as a function of depth into the cloud, assuming a cloud of constant density n illuminated by an external FUV (6 eV < E < 13.6 eV) flux G_0 (scaling factor in multiples of…
To understand the origin of water line emission and absorption during high-mass star formation, we decompose high-resolution Herschel-HIFI line spectra toward 19 high-mass star-forming regions into three distinct physical components.…
Water is a sensitive tracer of physical conditions in star-forming regions because of its large abundance variations between hot and cold regions. We use spectrally resolved observations of rotational lines of H$_2$O and its isotopologs…
New 3.3--3.6~$\mu$m spectra were obtained of nine young stellar objects embedded in molecular clouds. An absorption feature at $\sim$3.47~$\mu$m (2880~cm$^{-1}$) with FWHM$\sim$0.09 $\mu$m (80 cm$^{-1}$), first identified by Allamandola et…