Search Publications
XMM-Newton X-ray spectroscopy of classical T Tauri stars
Schmitt, J. H. M. M.; Robrade, J.
We present results from a comparative study of XMM-Newton observations of four classical T Tauri stars (CTTS), namely
Simultaneous optical and X-ray observations of a giant flare on the ultracool dwarf LP 412-31
Liefke, C.; Schmitt, J. H. M. M.; Micela, G. +1 more
Cool stars are known to produce flares probably as a result of the magnetic reconnection in their outer atmospheres. We present simultaneous XMM-Newton optical V band and X-ray observations of the M8 dwarf LP 412-31. During the observation a giant flare occurred, with an optical amplitude of 6 mag and total energy of 3 × 1032 erg in bot…
Amorphous alumina in the extended atmosphere of α Orionis
Waters, L. B. F. M.; Eriksson, K.; Hony, S. +7 more
In this paper we study the extended atmosphere of the late-type supergiant α Orionis. Infrared spectroscopy of red supergiants reveals strong molecular bands, some of which do not originate in the photosphere but in a cooler layer of molecular material above it. Lately, these layers have been spatially resolved by near and mid-IR interferometry. I…
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. II. SDSS J0924+0219: the redshift of the lensing galaxy, the quasar spectral variability and the Einstein rings
Magain, P.; Dye, S.; Meylan, G. +4 more
Aims.To provide the observational constraints required to use the gravitationally lensed quasar SDSS J0924+0219 for the determination of H0 from the time delay method. We measure here the redshift of the lensing galaxy, we show the spectral variability of the source, and we resolve the lensed host galaxy of the source.
Methods.We pr…
Resolving the compact dusty discs around binary post-AGB stars using N-band interferometry
Waters, L. B. F. M.; Jaffe, W.; Paresce, F. +8 more
We present the first mid-IR long baseline interferometric observations of the circumstellar matter around binary post-AGB stars. Two objects,
A general model for the identification of specific PAHs in the far-IR
Joblin, C.; Toublanc, D.; Mulas, G. +1 more
Context: .In the framework of the interstellar PAH hypothesis, far-IR skeletal bands are expected to be a fingerprint of single species in this class.
Aims: .A detailed model of the photo-physics of interstellar PAHs is required for such single-molecule identification of their far-IR features in the presently available Infrared Space Observato…
Unveiling the nature of INTEGRAL objects through optical spectroscopy. II. The nature of four unidentified sources
Palazzi, E.; Masetti, N.; Walter, R. +9 more
We present new results from our optical spectrophotometric campaign ongoing at the Astronomical Observatory of Bologna in Loiano (Italy) on hard X-ray sources detected by INTEGRAL. We have observed spectroscopically the putative optical counterparts of four more INTEGRAL sources, IGR J12391-1610, IGR J18406-0539, 2E 1853.7+1534 and IGR J19473+4452…
Oxygen abundances in metal-poor subgiants as determined from [O I], O I and OH lines
Gustafsson, B.; Asplund, M.; Nissen, P. E. +2 more
The debate on the oxygen abundances of metal-poor stars has its origin in contradictory results obtained using different abundance indicators. To achieve a better understanding of the problem we have acquired high quality spectra with the Ultraviolet and Visual Echelle Spectrograph at VLT, with a signal-to-noise of the order of 100 in the near ult…
The timing of relativistic proton acceleration in the 20 January 2005 flare
Simnett, G. M.
Understanding the energy budget in large solar flares requires a good knowledge of how and where the energetic charged particles are accelerated. If they are mainly accelerated by a Coronal Mass Ejection (CME)-driven shock, then they do not have to derive their energy from the flare region. Conversely, if the CME does not accelerate the particles,…
Outflows from young objects observed with the ISO-LWS. I. Fine structure lines [O I] 63 µm, [O I] 145 µm and [C II] 157 µm
Liseau, R.; Justtanont, K.; Tielens, A. G. G. M.
Far infrared fine structure line data from the ISO archive have been extracted for several hundred YSOs and their outflows, including molecular (CO) outflows, optical jets and Herbig-Haro (HH) objects. Given the importance of these lines to astrophysics, their excitation and transfer ought to be investigated in detail and, at this stage, the relia…