Following the recent discovery of γ rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to γ rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to γ -ray frequencies was followed by an increase of radio emission after less than two months from the peak of the γ -ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.

Abstract. We present sub-milliarcsecond observations of SiO masers in the late-type stars IRC +10011 and χ Cyg. We have used the NRAO Very Long Baseline Array (VLBA) to map the 43 GHz (v = 1, 2 J = 1-0) and the 86 GHz (v = 1, 2 J = 2−1) SiO masers. All the transitions have been imaged except the v = 2 J = 2-1 in IRC +10011. We report the first VLBI map of the v = 1 J = 2-1 28 SiO maser in IRC +10011 as well as the first VLBA images of SiO masers in an S-type Mira variable, χ Cyg. In this paper we have focused on the study of the relative spatial distribution of the different observed lines. We have found that in some cases the observational results are not reproduced by the current theoretical pumping models, either radiative or collisional. In particular, for IRC +10011, the v = 1 J = 1-0 and J = 2-1 28 SiO lines have different spatial distributions and emitting region sizes, the J = 2-1 emission being located in an outer region of the envelope. For χ Cyg, the distributions also differ, but the sizes of the masing regions are comparable. We suggest that the line overlaps between rovibrational transitions of two abundant molecular species, H 2 O and 28 SiO, is a possible explanation for the discrepancies found between the observations and the theoretical predictions. We have introduced this overlapping process in the calculations of the excitation of the SiO molecule. We conclude that the line overlaps can strongly affect the excitation of SiO and may reproduce the unexpected observational results for the two sources studied.

Context. OH 231.8+4.2 is a well studied preplanetary nebula (pPN) around a binary stellar system that shows a remarkable bipolar outflow. Aims. To study the structure and kinematics of the inner 10-80 AU nebular regions probed by SiO and H 2 O maser emission, where the agents of wind collimation are expected to operate, in order to gain insights into the, yet poorly known, processes responsible for the shaping of bipolar pPNe. Methods. We performed high-resolution observations of the H 2 O 6 1,6 -5 2,3 and 28 SiO v = 2, J = 1-0 maser emissions with the Very Long Baseline Array. The absolute position of both emission distributions were recovered using the phase referencing technique, and accurately registered in HST optical images. Results. Maps of both masers were produced and compared. H 2 O maser clumps are found to be distributed in two areas of 20 mas in size spatially displaced by ∼60 milli-arcs along an axis oriented nearly north-south. SiO masers are tentatively found to be placed between the two H 2 O maser emitting regions, probably indicating the position of the Mira component of the system. Conclusions. The SiO maser emission traces an inner equatorial component with a diameter of 12 AU, probably a disk rotating around the M-type star. Outwards, we detect in the H 2 O data a pair of polar caps, separated by 80 AU. We believe that the inner regions of the nebula probably have been altered by the presence of the companion, leading to an equator-to-pole density contrast that may explain the lack of H 2 O masers and strong SiO maser emission in the denser, equatorial regions.

Cyanogen (NCCN) is the simplest member of the series of dicyanopolyynes. It has been hypothesized that this family of molecules can be important constituents of interstellar and circumstellar media, although the lack of a permanent electric dipole moment prevents its detection through radioastronomical techniques. Here we present the first solid evidence of the presence of cyanogen in interstellar clouds by detection of its protonated form toward the cold dark clouds TMC-1 and L483. Protonated cyanogen (NCCNH + ) has been identified through the J = 5−4 and J = 10−9 rotational transitions using the 40 m radiotelescope of Yebes and the IRAM 30 m telescope. We derive beam-averaged column densities for NCCNH + of (8.6 ± 4.4) × 10 10 cm −2 in TMC-1 and (3.9 ± 1.8) × 10 10 cm −2 in L483, which translate into fairly low fractional abundances relative to H 2 , in the range (1-10) × 10 −12 . The chemistry of protonated molecules in dark clouds is discussed, and it is found that, in general terms, the abundance ratio between the protonated and non-protonated forms of a molecule increases with increasing proton affinity. Our chemical model predicts an abundance ratio NCCNH + /NCCN of ∼10 −4 , which implies that the abundance of cyanogen in dark clouds could be as high as (1-10) × 10 −8 relative to H 2 , i.e., comparable to that of other abundant nitriles such as HCN, HNC, and HC 3 N.

Abstract. This paper presents and discusses the final data set of a long-term and short-spaced monitoring of 21 SiO maser sources, mostly evolved stars, carried out in two SiO maser lines at 43 GHz with the Observatorio Astronómico Nacional 13.7 m telescope at the Centro Astronómico de Yebes (Guadalajara, Spain). In most objects, more than 80 spectra per transition over a period of 11 years have been recorded. The new data presented here, previously unpublished, represent nearly 50% of the total SiO data collected in the project. In addition, the availability of optical light curves from the AAVSO for most of the objects during the whole period of the SiO monitoring, ground-based near-IR data for four sources overlapping with 3 to 5 observed SiO periods, and DIRBE near-IR data covering a significant portion of an SiO period in 10 sources, make this data set a unique reference for comparing optical, NIR and SiO variability in order to elucidate the physical mechanisms that pump SiO masers in evolved stars. The basis for the conclusions obtained in this work comes from a numerical time series analysis of the suitable SiO, optical and NIR light curves in regular variables to obtain precise values of the periods and phase lags between the different curves. This analysis shows evidence that in regular variable evolved stars the three types of emission have the same period and that the SiO maxima happen in phase with NIR maxima and with a phase lag typically between 0.05 and 0.20 with respect to optical maxima. We conclude that in these objects the observational evidence presented in this work favors the radiative pumping of SiO masers against the collisional pumping.

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Context. There is growing evidence of relativistic jets in radio-loud narrow-line Seyfert 1 (RL-NLS1) galaxies. Aims. We constrain the observational properties of the radio emission in the first RL-NLS1 galaxy ever detected in gamma-rays, PMN J0948+0022, i.e., its flux density and structure in both total intensity and polarization, its compactness, and variability. Methods. We performed three real-time e-VLBI observations of PMN J0948+0022 at 22 GHz, using a global array including telescopes in Europe, East Asia, and Australia. These are the first e-VLBI science observations ever carried out with a global array, reaching a maximum baseline length of 12 458 km. The observations were part of a large multiwavelength campaign in 2009. Results. The source is detected at all three epochs. The structure is dominated by a bright component, more compact than 55 μas, with a fainter component at a position angle θ ∼ 35 • . Relativistic beaming is required by the observed brightness temperature of 3.4 × 10 11 K. Polarization is detected at a level of about 1%. Conclusions. The parameters derived by the VLBI observations, in addition to the broad-band properties, confirm that PMN J0948+0022 is similar to flat spectrum radio quasars. Global e-VLBI is a reliable and promising technique for future studies.

We present observations of the v = 0 J = 2-1 thermal emission of SiO from the very luminous evolved star IRC +10420, performed with the Plateau de Bure interferometer. Our high-resolution maps show that the emission comes from a huge hollow shell, with a typical radius of ∼10 17 cm, that is expanding at ∼35 km s −1 . This surprising result is strengthened by model fitting of the flux distribution, that explains the observations assuming that the width of the shell is not larger than half its typical radius. The origin of this feature is discussed.