Search Publications
ιHorologi, the first coronal activity cycle in a young solar-like star
Sanz-Forcada, J.; Stelzer, B.; Metcalfe, T. S.
Context. The shortest chromospheric (Ca ii H&K) activity cycle (1.6 yr) has been recently discovered in the young (~600 Myr) solar-like star ι Hor. Coronal X-ray activity cycles have only been discovered in a few stars other than the Sun, all of them with an older age and a lower activity level than ι Hor.
Aims: We intended to find the X-…
Magnetic field strength distribution of magnetic bright points inferred from filtergrams and spectro-polarimetric data
Veronig, A.; Utz, D.; Hanslmeier, A. +3 more
Context. Small scale magnetic fields can be observed on the Sun in G-band filtergrams as magnetic bright points (MBPs) or identified in spectro-polarimetric measurements due to enhanced signals of Stokes profiles. These magnetic fields and their dynamics play a crucial role in understanding the coronal heating problem and also in surface dynamo mo…
Probing the role of polycyclic aromatic hydrocarbons in the photoelectric heating within photodissociation regions
Teyssier, D.; Ossenkopf, V.; Goicoechea, J. R. +8 more
Aims: We observationally investigate the relation between the photoelectric heating efficiency in photodissociation regions (PDRs) and the charge of polycyclic aromatic hydrocarbons (PAHs), which are considered to play a key role in photoelectric heating.
Methods: Using PACS onboard Herschel, we observed six PDRs spanning a wide range of…
GRO J1008-57: an (almost) predictable transient X-ray binary
Klochkov, D.; Wilms, J.; Ferrigno, C. +13 more
A study of archival RXTE, Swift, and Suzaku pointed observations of the transient high-mass X-ray binary GRO J1008-57 is presented. A new orbital ephemeris based on pulse arrival-timing shows the times of maximum luminosities during outbursts of GRO J1008-57 to be close to periastron at orbital phase - 0.03. This makes the source one of a few for …
Activity of the Seyfert galaxy neighbours
Georgantopoulos, I.; Chavushyan, V.; Plionis, M. +4 more
We present a follow-up study of a series of papers concerning the role of close interactions as a possible triggering mechanism of AGN activity. We have already studied the close (≤100 h-1 kpc) and the large-scale (≤1 h-1 Mpc) environment of a local sample of Sy1, Sy2, and bright IRAS galaxies (BIRG) and of their respective c…
Overview of semi-sinusoidal stellar variability with the CoRoT satellite
Baglin, A.; Catelan, M.; Janot-Pacheco, E. +13 more
Context. To date, the CoRoT space mission has produced more than 124 471 light curves. Classifying these curves in terms of unambiguous variability behavior is mandatory for obtaining an unbiased statistical view on their controlling root-causes.
Aims: The present study provides an overview of semi-sinusoidal light curves observed by the CoRo…
The distance to NGC 1316 (Fornax A): yet another curious case
Della Valle, M.; Blakeslee, J. P.; Cantiello, M. +6 more
Aims: The distance of NGC 1316, the brightest galaxy in the Fornax cluster, provides an interesting test for the cosmological distance scale. First, because Fornax is the second largest cluster of galaxies within ≲25 Mpc after Virgo and, in contrast to Virgo, has a small line-of-sight depth; and second, because NGC 1316 is the single galaxy w…
Spatial distribution of water in the stratosphere of Jupiter from Herschel HIFI and PACS observations
Lara, L. M.; Hartogh, P.; Lellouch, E. +11 more
Context. In the past 15 years, several studies suggested that water in the stratosphere of Jupiter originated from the Shoemaker-Levy 9 (SL9) comet impacts in July 1994, but a direct proof was missing. Only a very sensitive instrument observing with high spectral/spatial resolution can help to solve this problem. This is the case of the Herschel S…
The asymmetric drift, the local standard of rest, and implications from RAVE data
Watson, F.; Munari, U.; Steinmetz, M. +13 more
Context. The determination of the local standard of rest (LSR), which corresponds to the measurement of the peculiar motion of the Sun based on the derivation of the asymmetric drift of stellar populations, is still a matter of debate. The classical value of the tangential peculiar motion of the Sun with respect to the LSR was challenged in recent…
BL Lacertae identifications in a ROSAT-selected sample of Fermi unidentified objects
Palazzi, E.; Sbarufatti, B.; Minniti, D. +15 more
The optical spectroscopic followup of 27 sources belonging to a sample of 30 high-energy objects selected by positionally cross correlating the first Fermi/LAT Catalog and the ROSAT All-Sky Survey Bright Source Catalog is presented here. It has been found or confirmed that 25 of them are BL Lacertae objects (BL Lacs), while the remaining two are G…