Related papers: Detection of CH$^{+}$, CH and H$_2$ molecules in t…

We discuss the detection of 14 rovibrational lines of CH$^+$, obtained with the iSHELL spectrograph on NASA's Infrared Telescope Facility (IRTF) on Maunakea. Our observations in the 3.49 - 4.13 $\mu$m spectral region, obtained with a 0.375"…

Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Guizhou, China, we detect the 21cm neutral atomic hydrogen absorption in the young planetary nebula IC 4997. The absorption arises from a shell also associated with…

Spectrophotometric data of the young planetary nebula M 3-27, from 2004 to 2021, are presented and discussed. We corroborate that the H I Balmer lines present features indicating they are emitted by the central star, therefore He I lines…

The unusual infrared emission patterns of CH$^+$, recently detected in the planetary nebula NGC 7027, are examined theoretically with high-accuracy rovibrational wavefunctions and $ab$ $initio$ dipole moment curves. The calculated…

We present an analysis of results on absorption from Ca II, Ca I, K I, and the molecules CH+, CH, C2, and CN that probes gas interacting with the supernova remnant IC443. The eleven directions sample material across the visible nebula and…

We present spectroscopic observations of the runaway reddened star HD 34078 acquired during the last three years at Observatoire de Haute Provence and McDonald Observatory as well as other spectra obtained since 1990. The drift of the line…

An infrared L- and M-band spectral survey, performed toward the young planetary nebula NGC 7027 with the iSHELL instrument on NASA's Infrared Telescope Facility (IRTF), has revealed more than 20 vibrational lines of the molecules HeH$^+$,…

Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5 GHz and 1234.6 GHz J = 1-0 and 2-1 rotational lines of {36}ArH^+ at…

Planetary nebulae are sites where ejected stellar material evolves into complex molecules, but the precise physical conditions and chemical routes that govern these processes are unclear. The presence of abundant carbon-rich molecules in…

High quality archival spectra of interstellar absorption from C I toward 9 stars, taken with the Goddard High Resolution Spectrograph on the Hubble Space Telescope, were analyzed. Our sample was supplemented by two sight lines, 23 Ori and…

The planetary nebula (PN) IC 4997 is one of a few rapidly evolving objects with variable brightness and nebular emission around a hydrogen-deficient star. In this study, we have determined the physical conditions and chemical abundances of…

Despite the many studies in the last decades, the low-ionisation structures (LISs) of planetary nebulae (PNe) still hold several mysteries. Recent imaging surveys have demonstrated that LISs are composed of molecular gas. Here we report…

We present echelle spectrophotometry of the Galactic H II region S 311. The data have been taken with the Very Large Telescope UVES echelle spectrograph in the 3100 to 10400 angstroms range. We have measured the intensities of 263 emission…

Aims. Excitation of far-infrared and submillimetric molecular lines may originate from nonreactive collisions, chemical formation, or far infrared, near-infrared, and optical fluorescences. As a template, we investigate the impact of each…

We present the results of a new epoch of a long-term photometric monitoring of the variable planetary nebula IC~4997. The integral $UBV$ light curves display a continuing brightening of 0.$^{m}15$ in $V$, a slight rise (<0.$^{m}1$) in $B$,…

Certain planetary nebulae contain shells, filaments, or globules of cold gas and dust whose heating and chemistry are likely driven by UV and X-ray emission from their central stars and from wind-collision-generated shocks. We present the…

Observations with the Short Wavelength Spectrometer (SWS) onboard the {\it Infrared Space Observatory} (ISO) have led to the first detection of the methyl radical ${\rm CH_3}$ in the interstellar medium. The $\nu_2$ $Q-$branch at 16.5…

We present deep optical spectra of the archetypal young planetary nebula (PN) NGC 7027, covering a wavelength range from 3310 to 9160 A. The observations were carried out by uniformly scanning a long slit across the entire nebular surface,…

We present high-sensitivity CH 9 cm ON/OFF observations toward 18 extra-galactic continuum sources that have been detected with OH 18 cm absorption in the Millennium survey with the Arecibo telescope. CH emission was detected toward six of…

With the Spitzer-IRS we have obtained the first mid-IR spectroscopy of NGC 7129, in the unusually strong outflow and in a ridge of H_2 emission near the Herbig Be star LkHalpha-234. The UV radiation field strength is estimated from PAH band…