Observing pulsating and exotic stars 24 hours a day - MUSICOS98
20 December 1998The fifth large MUSICOS (Multi-site continuous spectroscopy) campaign has just finished, lasting from 20 November to 14 December 1998. It involved 13 telescopes mostly equipped with cross-dispersedechelle spectrographs in Haute Provence, Pic du Midi, La Palma, SouthAfrica, ESO La Silla, Brazil, Kitt Peak, Xinglong, Mt Stromlo, Catania,Caucasus SAO. The campaign was coordinated daily by B.H. Foing and J. Oliveira (Space Science Department of ESA).Although some sites suffered snow and winds, the overall coverage was successful. S. Orlando (SSD) observed from Xinlong observatory near Beijing in Siberian winter, with temperatures of -15 deg.!
The goal of the MUSICOS project is to facilitate multi-site, multi-wavelength observations in stellar spectroscopy (PIs: Catala and Foing 1988, 1990). It can address asteroseismology, stellar surface structures and activity, circumstellar environments, support to space observations, in the context of the solar-stellar connection.
The project has so far organised five large ( and a few smaller) multi-site campaigns using existing or transportable spectrographs on 2 m class telescopes. A prototype spectrograph was designed, built and is in operation at Pic du Midi Observatory (Telescope Bernard Lyot). The ESA-MUSICOS spectrograph built and commissioned in May 1996 by B.H. Foing and collaborators, is presently installed in the 2.5m Isaac Newton Telescope in La Palma, Canary Islands and offered to the general community. It has been used for programmes of stellar variability, support to space observations, and as part of multi-site campaigns.
This was the largest campaign organised so far. Three rotating pulsating early-type stars, known to be multiperiodic, were monitored intensively over three weeks in order to determine unknown pulsation frequencies. More than 250 spectra were obtained for these targets (PI: J. Telting, INT La Palma).
The B star Omega Ori was monitored with more than 180 spectra over 3 weeks in order to detect multi-periodic variations with time-scales ranging from 2 to 10 hours. The behaviour of the disk envelope in H alpha was followed simultaneously to the photospheric line variability (PI: A.M. Hubert, Observatoi re de Paris-Meudon).
The RS CVn fast rotating active binaries EI Eridani and HR 1099 were monitored over more than 7 rotational periods to allow Doppler imaging of their surface photospheric spots, to study differential rotation and spots lifetimes. Also a chromospheric/coronal monitoring of extended active structures and of flare variability was conducted. We obtained more than 140 spectra respectively for each target (PIs: Foing, Co-PIs: Oliveira, Orlando , Washuettl).
The neutron star in Vela X1/HD77581 is the only one more massive than the canonical 1.4 solar mass. The system was monitored with MUSICOS98, to study the effects of non-radial pulsations and tidal forces on surface velocity fields of the supergiant companion, to understand non-orbital velocity excursions. More than 50 spectra of the target have been obtained (PI: L. Kaper, ESO).
The connection between stellar surface and wind structures was measured in three luminous supergiants Dzeta, Eps and Kappa Ori. More than 180 spectra were obtained for each over the three weeks campaign (PI: A. Kaufer, Heidelberg).
A collection of MUSICOS papers and data can be found at ftp://mus.obs-mip.fr/pub/.
Bernard H. Foing (MUSICOS PI)