Search Publications
X-ray rotational modulation of a supersaturated star in IC 2391
Micela, G.; Peres, G.; Sciortino, S. +1 more
We present evidence of X-ray rotational modulation on VXR45, a young fast rotator star, member of IC 2391. It is a dG9 spectral type star whose rotational period and X-ray luminosity make it a supersaturated star. Our X-ray observation, made with EPIC/PN on XMM-Newton, covers about two photometric rotational periods. The detection of X-ray rotatio…
Molecular gas in the central regions of the latest-type spiral galaxies
Schinnerer, E.; Böker, T.; Lisenfeld, U.
Using the IRAM 30 >m telescope, we have surveyed an unbiased sample of 47 nearby spiral galaxies of very late (Scd-Sm) Hubble-type for emission in the 12CO(1-0) and (2-1) lines. The sensitivity of our data (a few mK) allows detection of about 60% of our sample in at least one of the CO lines. The median detected H2 mass is…
Temporal variability of Mrk 421 from XMM-Newton observations
Haberl, F.; Papadakis, I. E.; Brinkmann, W. +1 more
We present the results of a detailed spectral and temporal analysis of the currently available XMM-Newton observations of the bright BL Lac object Mrk 421 using mainly the EPIC-PN data. The source was found in various intensity states differing by up to a factor of five in count rates. In general, the source is more variable and shows a harder spe…
The history of the iron Kalpha line profile in the Piccinotti AGN ESO 198-G24
Guainazzi, M.
This paper presents ASCA (July 1997), XMM-Newton (December 2000) and BeppoSAX (January 2001) observations of the Piccinotti Seyfert 1 galaxy ESO 198-G24. The BeppoSAX 0.1-200 keV spectrum exhibits reprocessing features, probably produced by an X-ray illuminated, relativistic accretion disk subtending a solid angle la 2 pi . During the XMM-Newton o…
Reprocessing the Hipparcos Intermediate Astrometric Data of spectroscopic binaries. II. Systems with a giant component
Pourbaix, D.; Boffin, H. M. J.
By reanalyzing the Hipparcos Intermediate Astrometric Data of a large sample of spectroscopic binaries containing a giant, we obtain a sample of 29 systems fulfilling a carefully derived set of constraints and hence for which we can derive an accurate orbital solution. Of these, one is a double-lined spectroscopic binary and six were not listed in…
The first detection of Far-Infrared emission associated with an extended HI disk. The case of NGC 891
Tuffs, R. J.; Popescu, C. C.
Spiral galaxies in the local universe are commonly observed to be embedded in extended disks of neutral hydrogen - the so called ``extended HI disks''. Based on observations made using the ISOPHOT instrument on board the Infrared Space Observatory, we report the first detection of cold dust in the extended HI disk of a spiral galaxy. The detection…
Unidentified infrared bands in the interstellar medium across the Galaxy
Lemke, D.; Lehtinen, K.; Mattila, K. +2 more
We present a set of 6-12 mu m ISOPHOT-S spectra of the general interstellar medium of the Milky Way. This part of the spectrum is dominated by a series of strong, wide emission features commonly called the Unidentified Infrared Bands. The sampled area covers the inner Milky Way from l = -60 degr to +60 degr with a ten-degree step in longitude and …
Chandra discovery of an X-ray jet and lobes in 3C 15
Leahy, J. P.; Kataoka, J.; Kawai, N. +5 more
We report the Chandra detection of an X-ray jet in 3C 15. The peak of the X-ray emission in the jet is 4.1'' (a projected distance of 5.1 kpc) from the nucleus, and coincident with a component previously identified in the radio and optical jets. We construct the spectral energy distribution (SED) for this component, optical knot C, and find that X…
SPI instrumental background characteristics
Boggs, S.; Knödlseder, J.; von Kienlin, A. +22 more
In its space environment the INTEGRAL observatory is subject to an intense irradiation by energetic cosmic-ray particles that leads, via nuclear interactions with the telescope and spacecraft materials, to an important background of false events. In this paper we present the characteristics of the instrumental background that is observed in the sp…
Lithium and rotation in F and G dwarfs and subgiants
Parthasarathy, M.; Mallik, Sushma V.; Pati, A. K.
Lithium abundances have been determined in 127 F and G Pop I stars based on new measurements of the equivalent width of the lambda 6707 Å Li I line from their high resolution CCD spectra. Distances and absolute magnitudes of these stars have been obtained from the Hipparcos Catalogue and their masses and ages derived, enabling us to investigate th…