Related papers: The Mid-Infrared [SIV]/[NeII] versus [NeIII]/[NeII…

We present our discovery of a narrow-line Baldwin effect, an anti-correlation between the equivalent width (EW) of a line and the flux of the associated continuum, in 5-20$\mu$m mid-infared lines from a sample of 68 Active Galactic Nuclei…

We study the near-infrared (NIR) scattering in LDN 1642, its correlation with the cloud structure, and the ability of dust models to simultaneously explain sub-millimetre emission, NIR extinction, and NIR scattering. We use observations…

The electron temperatures of high-metallicity (12+log(O/H) > 8.2) HII regions have been studied. The empirical ff relations which express the nebular-to- auroral [OIII] line ratio Q_3,O (as well as the nebular-to-auroral [OII] line ratio…

Our knowledge of circumstellar disks has traditionally been based on studies of dust. However, gas dominates the disk mass and its study is key to understand the star and planet formation process. Spitzer can access gas emission lines in…

We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on the high angular resolution 12 and 18um continuum fluxes from the AGN subarcsecond MIR atlas and 2-10 keV and…

We compare H-alpha, radio continuum, and Spitzer Space Telescope (SST) images of 58 planetary nebulae (PNe) recently discovered by the Macquarie-AAO-Strasbo- urg H-alpha PN Project (MASH) of the SuperCOSMOS H-alpha Survey. Using InfraRed…

We present deep spectroscopy of 17 very low mass (M* ~ 2.0x10^6 Msun to 1.4x10^9 Msun) and low luminosity (M_UV ~ -13.7 to -19.9) gravitationally lensed galaxies in the redshift range z~1.5-3.0. Deep rest-frame ultraviolet spectra reveal…

(Abridged) We present R~600, 10-37um spectra of 53 ULIRGs at z<0.32, taken using the IRS on board Spitzer. All of the spectra show fine structure emission lines of Ne, O, S, Si and Ar, as well as molecular Hydrogen lines. Some ULIRGs also…

We present an unprecedented spectroscopic survey of the CaII triplet + OI for a sample of 14 luminous ($-$26 $\gtrsim$ M$_V$ $\gtrsim$ $-$29), intermediate redshift (0.85 $\lesssim$ $z$ $\lesssim$ 1.65) quasars. The ISAAC spectrometer at…

GHZ2/GLASS-z12 has been recently observed by JWST with both NIRSpec and MIRI spectrographs, making it the most distant galaxy ($z_{spec}=12.34$) with complete spectroscopic coverage from rest-frame UV to optical. It is identified as a…

Recent analyses of nebular spectra have resulted in discrepant abundances from CNO forbidden and recombination lines. We consider independent methods of determining ion abundances for emission nebulae, comparing ion emission measures with…

Using the short-high module of the Infrared Spectrograph on the Spitzer Space Telescope, we have measured the [S IV] 10.51, [Ne II] 12.81, [Ne III] 15.56, and [S III] 18.71-micron emission lines in nine H II regions in the dwarf irregular…

Far-infrared (FIR) and mid-infrared (MIR) fine-structure lines (FSLs) provide key diagnostics of physical conditions in the interstellar medium (ISM). Building on empirical relations established in our previous work, we use photoionization…

Effects of young stellar clusters on their gas and dust environment are probed using mid-infrared (MIR) wavelengths. The strong MIR [NeIII]/[NeII] ratios (5 to 10) reveal the presence of current massive stars less than 5 Myr. Using MIR line…

Low-energy (~MeV) cosmic rays (CRs) ionize molecular clouds and create the neutral iron line (Fe I K\alpha) at 6.4 keV. On the other hand, high-energy (>~ GeV) CRs interact with the dense cloud gas and produce gamma rays. Based on a…

We present Keck/MOSFIRE spectra of the diagnostic nebular emission lines [OIII]5007,4959, [OII]3727, and H-beta for a sample of 15 redshift z=3.1-3.7 Ly-alpha emitters (LAEs) and Lyman break galaxies (LBGs). In conjunction with spectra from…

We uniformly analyze 136 optically detected PNe and candidates from the GLIMPSE-I survey in order to to develop robust, multi-wavelength, classification criteria to augment existing diagnostics and provide pure PN samples. PNe represent…

The physical conditions in typical starburst galaxies are investigated through critical infrared (IR) line ratios, as previously suggested by Lutz et al. (1998, A&A, 333, L75). The calculations by a composite model which consistently…

We analyze the reliability of oxygen abundances and ionization parameters obtained from different diagnostic diagrams. For this, we compiled from the literature observational emission line intensities and oxygen abundance of 446…

We provide a new method to derive heavy element abundances based on the unique suite of nebular lines in the mid- to far-infrared (IR) range. Using grids of photo-ionisation models that cover a wide range in O/H and N/O abundances, and…