New composite supernova remnant toward HESS J1844-030?

AIMS: HESS J1844-030 is a newly confirmed TeV source in the direction of the X-ray pulsar wind nebula (PWN) candidate G29.4+0.1 and the complex radio source G29.37+0.1, which is likely formed by the superposition of a background radio galaxy and a Galactic supernova remnant (SNR). We investigate the possible connection between the SNR, the PWN G29.4+0.1, and HESS J1844-030 to shed light on the astrophysical origin of the TeV emission. METHODS: We performed an imaging and spectral study of the X-ray emission from the PWN G29.4+0.1 using archival observations obtained with the Chandra and XMM-Newton telescopes. Public radio continuum and HI data were used to derive distance constraints for the SNR that is linked to G29.37+0.1 and to investigate the interstellar medium where it is expanding. We applied a simple model of the evolution of a PWN inside an SNR to analyze the association between G29.4+0.1 and the radio emission from G29.37+0.1. We compared the spectral properties of the system with the population of TeV PWNe to investigate if HESS J1844-030 is the very high energy counterpart of the X-ray PWN G29.4+0.1. RESULTS: We conclude that G29.4+0.1 is a PWN and that a point source embedded on it is the powering pulsar. The HI data revealed that the SNR linked to G29.37+0.1 is a Galactic source at 6.5 kpc and expanding in a nonuniform medium. From the analysis of the pulsar motion and the pressure balance at the boundary of X-ray emission, we conclude that G29.4+0.1 could be a PWN that is located inside its host remnant, forming a new composite SNR. Based on the magnetic field of the PWN obtained from the X-ray luminosity, we found that the population of electrons producing synchrotron radiation in the keV band can also produce IC photons in the TeV band. This suggests that HESS J1844-030 could be the very high energy counterpart of G29.4+0.1.Comment: Accepted for publication in A&A. The quality of some of the images has been degraded. Abstract length has been reduce

Sinopsis de las Corystospermaceae [Corystospermales, Pteridospermophyta] de Argentina : II. Estructuras fértiles

Fil: Petriella, Bruno. División Paleobotánica; Facultad de Ciencias Naturales y Museo; Universidad Nacional de La Plat

La reconstrucción de Dicroidium [Pteridospermopsida, Corystospermaceae]

Fil: Petriella, Bruno. División Paleobotánica; Facultad de Ciencias Naturales y Museo; Universidad Nacional de La Plat

El género Lepidodendropsis Lutz del Carbónico Inferior de Argentina

Fil: Arrondo, Oscar G.. División Paleobotánica; Facultad de Ciencias Naturales y Museo; Universidad Nacional de La PlataFil: Petriella, Bruno. División Paleobotánica; Facultad de Ciencias Naturales y Museo; Universidad Nacional de La Plat

Sistemática y vinculaciones de las Corystospermaceae H. Thomas

Fil: Petriella, Bruno. División Paleobotánica. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

Discovering a misaligned CO outflow related to the red MSX source G034.5964-01.0292

The red MSX source G034.5964-01.0292 (MSXG34), catalogued as a massive YSO, was observed in molecular lines with the aim of discover and study molecular outflows. We mapped a region of 3'x3' centered at MSXG34 using the Atacama Submillimeter Telescope Experiment in the 12CO J=3-2 and HCO+ J=4-3 lines with an angular and spectral resolution of 22" and 0.11 km/s, respectively. Additionally, public 13CO J=1-0 and near-IR UKIDSS data obtained from the Galactic Ring Survey and the WFCAM Sciencie Archive, respectively, were analyzed. We found that the 12CO spectra towards the YSO present a self-absorption dip, as it is usual in star forming regions, and spectral wings evidencing outflow activity. The HCO+ was detected only towards the MSXG34 position at v_LSR ~ 14.2 km/s, in coincidence with the 12CO absorption dip and approximately with the velocity of previous ammonia observations. HCO+ and NH3 are known to be enhanced in molecular outflows. Analyzing the spectral wings of the 12CO line, we discovered misaligned red- and blue-shifted molecular outflows associated with MSXG34. The near-IR emission shows a cone-like shape nebulosity composed by two arc-like features related to the YSO, which can be due to a cavity cleared in the circumstellar material by a precessing jet. This can explain the misalignment in the molecular outflows. From the analysis of the 13CO J=1--0 data we suggest that the YSO is very likely related to a molecular clump ranging between 10 and 14 km/s. This suggests that MSXG34, with an associated central velocity of about 14 km/s, may be located in the background of this clump. Thus, the blue-shifted outflow is probably deflected by the interaction with dense gas along the line of sight.Comment: Accepted in A&A June 10, 201

El género Lycopodiopsis [Lycopodiopsidaceae, Lepidodendrales], del carbónico Medio-Pérmico Inferior de la Argentina

Fil: Arrondo, Oscar G.. División Paleobotánica; Facultad de Ciencias Naturales y Museo; Universidad Nacional de La PlataFil: Petriella, Bruno. División Paleobotánica; Facultad de Ciencias Naturales y Museo; Universidad Nacional de La Plat

The HII region G35.673-00.847: another case of triggered star formation?

As part of a systematic study that we are performing with the aim to increase the observational evidence of triggered star formation in the surroundings of HII regions, we analyze the ISM around the HII region G35.673-00.847, a poorly studied source. Using data from large-scale surveys: Two Micron All Sky Survey, Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), MIPSGAL, Galactic Ring Survey (GRS), VLA Galactic Plane Survey (VGPS), and NRAO VLA Sky Survey (NVSS) we performed a multiwavelength study of G35.673-00.847 and its surroundings. The mid IR emission, shows that G35.673-00.847 has an almost semi-ring like shape with a cut towards the galactic west. The radius of this semi-ring is about 1.5' (~1.6 pc, at the distance of ~3.7 kpc). The distance was estimated from an HI absorption study and from the analysis of the molecular gas. Indeed, we find a molecular shell composed by several clumps distributed around the HII region, suggesting that its expansion is collecting the surrounding material. We find several YSO candidates over the molecular shell. Finally, comparing the HII region dynamical age and the fragmentation time of the molecular shell, we discard the collect and collapse as the mechanism responsible for the YSOs formation, suggesting other processes such as radiative driven implosion and/or small-scale Jeans gravitational instabilities.Comment: Accepted for publication in A&A, 18 October 2010. Some figures were degraded to reduce file siz

Effect of salinity changes on the midgut gland of Artemesia longinaris (Decapoda, Penaeidae)

The response of the midgut gland of Artemesia longinaris to salinity changes was evaluated by analyzing its histological changes. Animals were exposed gradually and abruptly to 33, 29, 25 and 16 psu for different time intervals and readapted to 33 psu for 30 days. Individuals maintained 10 days at 16 psu showed the lowest survival and presented histopathologies which were not present in those readapted to 33 psu. Shrimps abruptly transferred from 33 to 16 psu died in 3-5 h but did not show midgut gland alterations likely due to the brief exposure. Only shrimps abruptly transferred from 33 to 25 psu presented histopathologies after 96 h. When readapted to 33 psu for 30 days, the midgut gland recovered an unaltered structure. Except E-cells, which did not vary in height among treatments, F, R and B-cells were taller in animals gradually adapted to 29 than to 16 psu. Abrupt salinity changes had a significant effect on the mean height of F, R and B-cells of those animals transferred from 33 to 25 psu (from 24 to 96 h after transfer F and R-cells heights decreased, and from 96 to 144 h after transfer B-cells height increased). Our study shows the effect of osmotic stress at the tissue level on the midgut gland and, at least partially, explains the reason for the mortalities at low salinities.Se evaluó la respuesta del hepatopáncreas de Artemesia longinaris a los cambios de salinidad. Los animales fueron expuestos gradual y abruptamente a 33, 29, 25 y 16 psu durante distintos intervalos y readaptados a 33 psu por 30 días. Los individuos gradualmente adaptados a 16 psu tuvieron baja supervivencia y presentaron alteraciones histológicas ausentes en los readaptados a 33 psu. Aquellos transferidos repentinamente de 33 a 16 psu murieron en 3-5 h pero no mostraron alteraciones, posiblemente debido a la breve exposición. Sólo los transferidos repentinamente de 33 a 25 psu por más de 96 h presentaron daño tisular. Cuando se readaptaron a 33 psu durante 30 días, el hepatopáncreas mostró una estructura normal. Exceptuando las células E que no variaron en altura entre tratamientos, las F, R y B fueron más altas en los animales gradualmente adaptados de 33 a 29 psu. Los cambios súbitos de salinidad tuvieron un efecto significativo en la altura media de las células F, R y B solamente en animales transferidos de 33 a 25 psu (24 a 96 h después de la transferencia disminuyó la altura de las células F y R, y 96 a 144 h después hubo un aumento en la altura de las células B). El presente estudio muestra el efecto de los cambios de salinidad sobre el hepatopáncreas y explica, al menos parcialmente, la razón de la mortalidad a bajas salinidades