Search Publications
Observing Mkn 421 with XMM-Newton: The EPIC-PN point of view
Tagliaferri, G.; Ghisellini, G.; Tavecchio, F. +1 more
We present three observations (four exposures) of Mkn 421 performed by XMM-Newton in November and December 2002, concentrating on the EPIC-PN camera data. The X-ray spectra were soft and steepened toward high energies. The source was highly variable and the hardness ratio plots displayed a clear harder-when-stronger correlation. During two complet…
Mid-infrared spectral evidence for a luminous dust enshrouded source in Arp 220
Lutz, D.; Siebenmorgen, R.; Tielens, A. G. G. M. +3 more
We have re-analyzed the 6-12 µm ISO spectrum of the ultra-luminous infrared galaxy Arp 220 with the conclusion that it is not consistent with that of a scaled up version of a typical starburst. Instead, both template fitting with spectra of the galaxies NGC 4418 and M 83 and with dust models suggest that it is best represented by combination…
XMM-Newton survey of the Local Group galaxy M 33
Pietsch, W.; Haberl, F.; Hatzidimitriou, D. +3 more
In an XMM-Newton raster observation of the bright Local Group spiral galaxy
A purely geometric distance to the binary star Atlas, a member of the Pleiades
Eyer, L.; North, P.; Groenewegen, M. A. T. +4 more
We present radial velocity and new interferometric measurements of the double star Atlas, which permit, with the addition of published interferometric data, to precisely derive the orbital parameters of the binary system and the masses of the components. The derived semi-major axis, compared with its measured angular size, allows to determine a di…
Wind clumping and the wind-wind collision zone in the Wolf-Rayet binary γ2 Velorum observations at high and low state. XMM-Newton observations at high and low state
Schmutz, W.; Raassen, A. J. J.; Mewe, R. +7 more
We present XMM-Newton observations of γ2 Velorum (WR 11, WC8+O7.5III, P = 78.53 d), a nearby Wolf-Rayet binary system, at its X-ray high and low states. At high state, emission from a hot collisional plasma dominates from about 1 to 8 keV. At low state, photons between 1 and 4 keV are absorbed. The hot plasma is identified with the shoc…
Spatially and spectrally resolved 10 µm emission in Herbig Ae/Be stars
Waters, L. B. F. M.; Dominik, C.; van Boekel, R. +3 more
We present new mid-infrared spectroscopy of the emission from warm circumstellar dust grains in the Herbig Ae stars HD 100546, HD 97048 and HD 104237, with a spatial resolution of ≈0.9 arcsec. We find that the emission in the UIR bands at 8.6, 11.3 and (HD 97048 only) 12.7 µm is extended in the first two sources. The continuum emission is re…
Unveiling the nature of three INTEGRAL sources through optical spectroscopy
Palazzi, E.; Masetti, N.; Malizia, A. +2 more
The results of an optical spectroscopy campaign performed at the Astronomical Observatory of Bologna in Loiano (Italy) on three hard X-ray sources detected by INTEGRAL (IGR J17303-0601, IGR J18027-1455 and IGR J21247+5058) are presented. These data have allowed a determination of the nature for two of them, with IGR J17303-0601 being a low mass X-…
Structuring the HD 141569 A circumstellar dust disk. Impact of eccentric bound stellar companions
Augereau, J. C.; Papaloizou, J. C. B.
Scattered light images of the optically thin dust disk around the 5 Myr old star
Star formation rates of distant luminous infrared galaxies derived from Hα and IR luminosities
Elbaz, D.; Flores, H.; Cesarsky, C. J. +4 more
We present a study of the star formation rate (SFR) for a sample of 16 distant galaxies detected by ISOCAM at 15 µm in the CFRS0300+00 and CFRS1400+52 fields. Their high quality and intermediate resolution VLT/FORS spectra have allowed a proper correction of the Balmer emission lines from the underlying absorption. Extinction estimates using…
Temperature gradients in XMM-Newton observed REFLEX-DXL galaxy clusters at z ∼ 0.3
Zhang, Y. -Y.; Finoguenov, A.; Böhringer, H. +3 more
We present XMM-Newton results on the temperature profiles of a volume-limited sample of galaxy clusters at redshifts z∼0.3, selected from the REFLEX survey (REFLEX-DXL sample). In the spectral analysis, where only the energies above 1 keV were considered, we obtained consistent results for the temperature derived from the pn, MOS1 and MOS2 data. U…