Abstract. We carried out optical observations of the field of the X-ray pulsator RX J0806.3+1527. A blue V = 21.1 star was found to be the only object consistent with the X-ray position. VLT FORS spectra revealed a blue continuum with no intrinsic absorption lines. Broad (v ∼ 1500 km s −1 ), low equivalent width (∼-1 ÷ -6Å) emission lines from the HeII Pickering series were clearly detected. B, V and R time-resolved photometry revealed the presence of ∼15% pulsations at the ∼321 s X-ray period, confirming the identification. These findings, together with the period stability and absence of any additional modulation in the 1 min−5 hr period range, argue in favour of the orbital interpretation of the 321 s pulsations. The most likely scenario is thus that RX J0806.3+1527 is a double degenerate system of the AM CVn class. This would make RX J0806.3+1527 the shortest orbital period binary currently known and one of the best candidates for gravitational wave detection.

Abstract. We Maps of the distribution of the spotted regions on the photosphere of the binary components were derived using the Maximum Entropy and Tikhonov photometric regularization criteria. Rotational modulation was observed in Hα and He  D 3 in anti-correlation with the photometric light curves. Both flares occurred at the same binary phase (0.85), suggesting that these events took place in the same active region. Simultaneous X-ray observations, performed by ASM on board RXTE, show several flare-like events, some of which correlate well with the observed optical flares. Rotational modulation in the X-ray light curve has been detected with minimum flux when the less active G5 V star was in front. A possible periodicity in the X-ray flare-like events was also found.

Abstract.The 12 C/ 13 C isotope ratio is a tracer of stellar yields and the efficiency of mixing in the ISM. 12 CH + / 13 CH + is not affected by interstellar chemistry, and is the most secure way of measuring 12 C/ 13 C in the diffuse ISM. R = 12 C/ 13 C is 90 in the solar system. Previous measurements of 12 CH + λλ3957.7,4232.3 and 13 CH + λλ3958.2,4232.0 absorption toward nearby stars indicate some variations in 12 C/ 13 C, with values ranging from 40 to 90 suggesting inefficient mixing. Except for the cloud toward ζOph, these R values are strongly affected by noise. With UVES on the VLT we have improved on the previous interstellar 12 C/ 13 C measurements. The weighted 12 C/ 13 C ratio in the local ISM is 78.27 ± 1.83, while the weighted dispersion of our measurements is 12.7, giving a 6.9σ scatter. Thus we report on a 6.9σ detection of 16.2% root-mean-square variations in the carbon isotopic ratio on scales of ∼100 pc: R = 74.7 ± 2.3 in the ζOph cloud, while R = 88.6 ± 3.0 toward HD 152235 in the Lupus clouds, R = 62.2 ± 5.3 towards HD 110432 in the Coalsack, and R = 98.9 ± 10.1 toward HD 170740. The observed variations in 13 C/ 12 C are the first significant detection of chemical heterogeneity in the local ISM.

Context. The 12 C/ 13 C isotope ratio in the interstellar medium (ISM), and its evolution with time, is an important tracer of stellar yields. Spatial variations of this ratio can be used to study mixing in the ISM. Aims. We want to determine this ratio and its spatial variations in the local ISM from CH + absorption lines in the optical towards early-type stars. The aim is to determine the average value for the local ISM and study possible spatial variations. Methods. We observed a large number of early-type stars with Feros to extend the sample of suitable target stars for CH + isotope studies. The best suited targets were observed with Uves with higher signal-to-noise ratio and spectral resolution to determine the isotope ratio from the interstellar CH + lines. This study significantly expands the number of 13 CH + detections. Results. We find an average ratio of R = 76.27 ± 1.94 or, for f = 1/R, f = (120.46 ± 3.02) × 10 −4 . The scatter in f is 6.3 × σ( f ). This findings strengthens the case for chemical inhomogeneity in the local ISM, with important implications for the mixing in the ISM. Given the large scatter, the present-day value in the ISM is not significantly larger than the solar value, which corresponds to the local value 4.5 Gyr ago.

New methods and tools are needed to exploit the unprecedented source of information made available by the completed and ongoing whole genome sequencing projects. The Narcisse database is dedicated to the study of genome conservation, from sequence similarities to conserved chromosomal segments or conserved syntenies, for a large number of animals, plants and bacterial completely sequenced genomes. The query interface, a comparative genome browser, enables to navigate between genome dotplots, comparative maps and sequence alignments. The Narcisse database can be accessed at http://narcisse.toulouse.inra.fr.