Sacha Hony

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We investigate the molecular bands in carbon-rich AGB stars in the Large Magellanic Cloud (LMC), using the InfraRed Spectrograph (IRS) on board the Spitzer Space Telescope (SST) over the 5–38 µm range. All 26 low-resolution spectra show acetylene (C 2 H 2) bands at 7 and 14 µm. The hydrogen cyanide (HCN) bands at these wavelengths are very weak or absent.(More)
We have obtained 2.5–45 µm spectra of a sample of compact H ii regions, YSOs and evolved stars in order to study the origin and evolution of interstellar Polycyclic Aromatic Hydrocarbon molecules (PAHs). Besides the well–known, strong PAH bands at 3.3, 6.2, 7.7, 8.6, and 11.2 µm, these spectra reveal for the first time, a ubiquitous emission plateau from 15(More)
The Infrared Space Observatory (ISO) has provided the first complete mid-IR spectra for a wide range of objects. Almost all of these spectra are dominated by the well-known infrared emission features at 3.3, 6.2, 7.7, and 11.2 µm, the so-called Unidentified Infra-Red (UIR) features. Besides the major features, there is an array of minor features and broad(More)
We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220(More)
(Affiliations are available in the online edition) ABSTRACT By combining Herschel-SPIRE data with archival Spitzer, H i , and CO maps, we investigate the spatial distribution of gas and dust in the two famous grand-design spirals M 99 and M 100 in the Virgo cluster. Thanks to the unique resolution and sensitivity of the Herschel-SPIRE pho-tometer, we are(More)
With appropriate spatial resolution, images of spiral galaxies in thermal infrared (∼10 μm and beyond) often reveal a bright central component, distinct from the stellar bulge, superimposed on a disk with prominent spiral arms. ISO and Spitzer studies have shown that much of the scatter in the mid-infrared colors of spiral galaxies is related to changes in(More)
The Herschel Reference Survey is a guaranteed time Herschel key project and will be a benchmark study of dust in the nearby universe. The survey will complement a number of other Herschel key projects including large cosmological surveys that trace dust in the distant universe. We will use Herschel to produce images of a statistically-complete sample of 323(More)
We present 10−15 µm spectra of a sample of H ii regions, YSOs and evolved stars that show strong unidentified infrared emission features, obtained with the ISO/SWS spectrograph on-board ISO. These spectra reveal a plethora of emission features with bands at 11.0, 11.2, 12.0, 12.7, 13.5 and 14.2 µm. These features are observed to vary considerably in(More)
We present the 2.4−45 µm ISO-SWS spectrum of the Be star γ Cas (B0.5 IVe). The spectrum is characterised by a thermal continuum which can be well fit by a power-law S ν ∝ ν 0.99 over the entire SWS wavelength range. For an isothermal disc of ionized gas with constant opening angle, this correponds to a density gradient ρ(r) ∝ r −2.8. We report the detection(More)
(Affiliations are available in the online edition) ABSTRACT We present Herschel SPIRE and PACS photometeric observations of the low metallicity (Z ∼ 0.35 Z) nearby dwarf galaxy, NGC 1705, in six wavelength bands as part of the Dwarf Galaxy Survey guaranteed time Herschel key program. We confirm the presence of two dominant circumnuclear IR-bright regions(More)