Published in The Astrophysical Journal Supplement Series
We present a comprehensive and sensitive unbiased survey of interstellar features in the near-UV range (3050–3700 Å). We combined a large number of VLT/UVES archival observations of a sample of highly reddened early-type stars—typical diffuse interstellar band targets—and unreddened standards. We stacked the individual observations to obtain a redd...
Published in The Astrophysical Journal
We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containi...
Published in The Astrophysical Journal
HR 4049 is a peculiar evolved binary surrounded by a circumbinary disk. Mid- infrared observations show that the disk is rich in molecular gas and radially extended. To study the properties of this disk, we re-analyzed a set of near-infrared observations at high spectral resolution obtained with Gemini-Phoenix. These data cover absorption lines ori...
Published in Monthly Notices of the Royal Astronomical Society
We have selected a homogeneous sample of asymptotic giant branch (AGB) stars in the Galactic bulge population from the ISOGAL survey. Our target stars cover a wide range of mass-loss rates (∼ 10− 8–10− 4 M⊙ yr− 1) and differ primarily by their age on the AGB. This homogeneous sample is thus ideally suited to study the dust formation process as a fu...
Published in ScienceOpen Astronomy & Astrophysics
Context. The unknown identity of the diffuse interstellar band (DIB) carriers poses one of the longest standing unresolved problems in astrophysics. While the presence, properties, and behaviour of hundreds of optical DIBs between 4000 Å and 9000 Å have been well established, information on DIBs in both the ultra-violet and near-infrared (NIR) rang...
Published in The Astrophysical Journal
Infrared spectra of carbon-rich objects that have evolved off the asymptotic giant branch reveal a range of dust properties, including fullerenes, polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and several unidentified features, including the 21 μm emission feature. To test for the presence of fullerenes, we used the position and ...
Published in The Astrophysical Journal Supplement Series
A significantly updated version of the NASA Ames PAH IR Spectroscopic Database, the first major revision since its release in 2010, is presented. The current version, version 2.00, contains 700 computational and 75 experimental spectra compared, respectively, with 583 and 60 in the initial release. The spectra span the 2.5-4000 μm (4000-2.5 cm-1) r...
Published in The Astrophysical Journal
We present a detailed analysis of the mid-infrared spectrum of the peculiar evolved object HR 4049. The full Spitzer-IRS high-resolution spectrum shows a wealth of emission with prominent features from CO 2 and H 2 O and possible contributions from HCN and OH. We model the molecular emission and find that it originates from a massive (M gsim 8× 10–...
Published in The Astrophysical Journal
Fullerenes have recently been identified in space and they may play a significant role in the gas and dust budget of various astrophysical objects including planetary nebulae (PNe), reflection nebulae, and H II regions. The tenuous nature of the gas in these environments precludes the formation of fullerene materials following known vaporization or...
Published in Formation and Evolution of Solids in Space
In this contribution we describe the techniques used to infer properties of the carriers of the Diffuse Interstellar Bands (DIBs) from the analysis of astronomical data with emphasis on the recent results obtained from so-called single cloud observations. All results seem consistent with large carbonaceous gas phase molecules like PAHs and fulleren...
Published in The Astrophysical Journal
We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds: Tc1, SMP SMC 16, and SMP LMC 56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fulle...
Published in Proceedings of the International Astronomical Union
In recent years, the fullerene species C 60 (and to a lesser extent also C 70) has been reported in the mid-IR spectra of various astronomical objects. Cosmic fullerenes form in the circumstellar material of evolved stars, and survive in the interstellar medium (ISM). It is not entirely clear how they form or what their excitation mechanism is.
Published in ScienceOpen Astronomy & Astrophysics
We report on the discovery of an infrared emission band in the Spitzer spectrum of the S-type AGB star NP Aurigae that is caused by TiO molecules in the circumstellar environment. We modeled the observed emission to derive the temperature of the TiO molecules (≈ 600 K), an upper limit on the column density (≈ 10 17.25 cm-2) and a lower limit on the...
Published in The Astrophysical Journal Letters
We report the detection of carbon monoxide (CO) emission from the young supernova remnant Cassiopeia A (Cas A) at wavelengths corresponding to the fundamental vibrational mode at 4.65 μm. We obtained AKARI Infrared Camera spectra toward four positions which unambiguously reveal the broad characteristic CO ro-vibrational band profile. The observed p...
Published in The Astrophysical Journal
Carbon-rich evolved stars from the asymptotic giant branch to the planetary nebula phase are characterized by a rich and complex carbon chemistry in their circumstellar envelopes. A peculiar object is the preplanetary nebula SMP LMC 11, whose Spitzer Infrared Spectrograph spectrum shows remarkable and diverse molecular absorption bands. To study ho...
Published in ScienceOpen Astronomy & Astrophysics
Context. The circumstellar environment of evolved stars is generally rich in molecular gas and dust. Typically, the entire environment is either oxygen-rich or carbon- rich, depending on the evolution of the central star. Aims. In this paper we discuss three evolved disc sources with evidence of atypical emission lines in their infrared spectra. Th...
Published in ScienceOpen Astronomy & Astrophysics
Context. The origin of the narrow optical emission bands seen towards the Red Rectangle is not yet understood. We investigate the proposal that these are caused by luminescence of large carbonaceous molecules. Aims. We aim to measure the polarisation of the optical narrow Red Rectangle bands (RRBs). Polarised signals of several percent could be exp...
Published in ScienceOpen Astronomy & Astrophysics
Context. Mass-loss occurring in red supergiants (RSGs) is a major contributor to the enrichment of the interstellar medium in dust and molecules. The physical mechanism of this mass loss is however relatively poorly known. Betelgeuse is the nearest RSG, and as such a prime object for high angular resolution observations of its surface (by interfero...
Context: Mass-loss occurring in red supergiants (RSGs) is a major contributor to the enrichment of the interstellar medium in dust and molecules. The physical mechanism of this mass loss is however relatively poorly known. Betelgeuse is the nearest RSG, and as such a prime object for high angular resolution observations of its surface (by interfero...
Published in The Astrophysical Journal
Vibronic bands of polycyclic aromatic hydrocarbons (PAHs) in the UV/visible range are often used to estimate the abundances of PAHs in the interstellar medium by comparing laboratory-measured spectra with astronomical observations. We investigate the errors introduced by associating theoretical electronic oscillator strengths with individual vibron...
