Search Publications
Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831
Piskunov, N.; Kochukhov, O.; Drake, N. A. +1 more
We investigate magnetic field geometry and surface distribution of chemical elements in the rapidly oscillating Ap star HR 3831. Results of the model atmosphere analysis of the spectra of this star are combined with the Hipparcos parallax and evolutionary models to obtain new accurate estimates of the fundamental stellar parameters: Teff
Mass segregation in young Magellanic Cloud star clusters: Four clusters observed with HST
Bellas-Velidis, I.; Kontizas, M.; Kontizas, E. +2 more
We present the results of our investigation on the phenomenon of mass segregation in young star clusters in the Magellanic Clouds. HST/WFPC2 observations on NGC 1818, NGC 2004 and NGC 2100 in the Large Magellanic Cloud and NGC 330 in the Small Magellanic Cloud have been used for the application of diagnostic tools for mass segregation: i) the radi…
Puzzling wind properties of young massive stars in SMC-N81
Schaerer, D.; Martins, F.; Hillier, D. J. +1 more
We present a quantitative study of massive stars in the High Excitation Blob N81, a compact star forming region in the SMC. The stellar content was resolved by HST, and STIS was used to obtain medium resolution spectra. The qualitative analysis of the stellar properties presented in Heydari-Malayeri et al. (\cite{papI}) is extended using non-LTE s…
Dust emission in early-type galaxies: The mid-infrared view
Madden, S. C.; Galliano, F.; Sauvage, M. +2 more
We present mid-infrared (MIR) maps for a sample of 18 early-type galaxies observed at 4.5, 6.7 and 15 µ m with the ISOCAM instrument on board the ISO satellite with a 6'' spatial resolution. We model the Spectral Energy Distribution (SED) of these galaxies using the stellar evolutionary synthesis model PÉGASE and we derive the MIR excess ove…
3D magnetic configuration of the Hα filament and X-ray sigmoid in NOAA AR 8151
Amari, T.; Régnier, S.
We investigate the structure and relationship of an Hα filament and an X-ray sigmoid observed in active region NOAA 8151. We first examine the presence of such structures in the reconstructed 3D coronal magnetic field obtained from the non-constant-α force-free field hypothesis using a photospheric vector magnetogram (IVM, Mees Solar Observatory).…
The diameter and evolutionary state of Procyon A. Multi-technique modeling using asteroseismic and interferometric constraints
Bordé, P.; Provost, J.; Berthomieu, G. +3 more
We report the angular diameter measurement obtained with the VINCI/VLTI instrument on the nearby star Procyon A (α CMi A, F5IV-V), at a relative precision of ± 0.9%. We obtain a uniform disk angular diameter in the K band of θUD = 5.376±0.047 mas and a limb darkened value of θLD = 5.448±0.053 mas. Together with the HIPPARCOS …
Coronal plasma flows and magnetic fields in solar active regions. Combined observations from SOHO and NSO/Kitt Peak
Marsch, E.; Xia, L. D.; Wiegelmann, T.
During the early days of the SOHO mission, SUMER observed a few active regions (ARs) connected with sunspots on the Sun and took their images and spectra in various EUV emission lines. In addition to these spectroscopic data magnetograms of the photospheric footpoint regions of the AR loops were available from the MDI on SOHO and the National Sola…
X-ray reprocessing in Seyfert galaxies: Simultaneous XMM-Newton/BeppoSAX observations
Perola, G. C.; Bianchi, S.; Guainazzi, M. +2 more
We selected a sample of eight bright unobscured (at least at the iron line energy) Seyfert galaxies observed simultaneously by XMM-Newton and BeppoSAX, taking advantage of the complementary characteristics of the two missions. The main results of our analysis can be summarized as follows: narrow neutral iron lines are confirmed to be an ubiquitous…
First determination of the dynamical mass of a binary L dwarf
Duchêne, G.; Martín, E. L.; Bouy, H. +11 more
We present here the results of astrometric, photometric and spectroscopic observations leading to the determination of the orbit and dynamical masses of the binary L dwarf 2MASSW J0746425+2000321. High angular resolution observations spread over almost 4 years and obtained with the Hubble Space Telescope (HST), the ESO Very Large Telescope (VLT), …
A possible age-metallicity relation in the Galactic thick disk?
Feltzing, S.; Bensby, T.; Lundström, I.
A sample of 229 nearby thick disk stars has been used to investigate the existence of an age-metallicity relation (AMR) in the Galactic thick disk. The results indicate that that there is indeed an age-metallicity relation present in the thick disk. By dividing the stellar sample into sub-groups, separated by 0.1 dex in metallicity, we show that t…