A survey of SiO 5-4 emission towards outflows from massive young stellar objects

Results are presented of a survey of SiO 5-4 emission observed with the James Clerk Maxwell Telescope (JCMT) towards a sample of outflows from massive young stellar objects. The sample is drawn from a single-distance study by Ridge & Moore. In a sample of 12 sources, the 5-4 line was detected in 5, a detection rate of 42 per cent. This detection rate is higher than that found for a sample of low-luminosity outflow sources, although for sources of comparable luminosity, it is in good agreement with the results of a previous survey of high luminosity sources. For most of the detected sources, the 5-4 emission is compact or slightly extended along the direction of the outflow. NGC6334I shows a clear bipolar flow in the 5-4 line. Additional data were obtained for W3-IRS5, AFGL5142 and W75N for the 2-1 transition of SiO using the Berkeley-Illinois-Maryland Association (BIMA) millimetre interferometer. There is broad agreement between the appearance of the SiO emission in both lines, though there are some minor differences. The 2-1 emission in AFGL5142 is resolved into two outflow lobes which are spatially coincident on the sky, in good agreement with previous observations. In general the SiO emission is clearly associated with the outflow. The primary indicator of SiO 5-4 detectability is the outflow velocity, i.e. the presence of SiO is an indicator of a high velocity outflow. This result is consistent with the existence of a critical shock velocity required to disrupt dust grains and subsequent SiO formation in post-shock gas. There is also weak evidence that higher luminosity sources and denser outflows are more likely to be detected.Comment: Accepted for publication in MNRA

A wide-angle outflow with the simultaneous presence of a high-velocity jet in the high-mass Cepheus A HW2 system

We present five epochs of VLBI water maser observations around the massive protostar Cepheus A HW2 with 0.4 mas (0.3 AU) resolution. The main goal of these observations was to follow the evolution of the remarkable water maser linear/arcuate structures found in earlier VLBI observations. Comparing the data of our new epochs of observation with those observed five years before, we find that at "large" scales of > 1" (700 AU) the main regions of maser emission persist, implying that both the surrounding medium and the exciting sources of the masers have been relatively stable during that time span. However, at smaller scales of < 0.1" (70 AU) we see large changes in the maser structures, particularly in the expanding arcuate structures R4 and R5. R4 traces a nearly elliptical patchy ring of ~ 70 mas size (50 AU) with expanding motions of ~ 5 mas/yr (15 km/s). This structure is probably driven by the wind of a still unidentified YSO located at the centre of the ring (~ 0.18" south of HW2). On the other hand, the R5 expanding bubble structure (driven by the wind of a previously identified YSO located ~ 0.6" south of HW2) is currently dissipating in the circumstellar medium and losing its previous degree of symmetry, indicating a very short-lived event. In addition, our results reveal, at scales of ~ 1" (700 AU), the simultaneous presence of a relatively slow (~ 10-70 km/s) wide-angle outflow (opening angle of ~ 102 deg, traced by the masers, and the fast (~ 500~km/s) highly collimated radio jet associated with HW2 (opening angle of ~ 18 deg, previously observed with the VLA. This simultaneous presence of a wide-angle outflow and a highly collimated jet associated with a massive protostar is similar to what is found in some low-mass YSOs. The implications of these results in the study of the formation of high-mass stars are discussed.Comment: 28 pages, 7 figures. Animations will be included as supporting material online (MNRAS web page

On the nature of outflows in intermediate-mass protostars: a case study of IRAS 20050+2720

Context. This is the third of a series of papers devoted to study in detail and with high-angular resolution intermediate-mass molecular outflows and their powering sources. Aims. The aim of this paper is to study the intermediate-mass YSO IRAS 20050+2720 and its molecular outflow, and put the results of this and the previous studied sources in the context of intermediate-mass star formation. Methods. We carried out VLA observations of the 7 mm continuum emission, and OVRO observations of the 2.7 mm continuum emission, CO(1-0), C18O(1-0), and HC3N(12-11) to map the core towards IRAS 20050+2720. The high-angular resolution of the observations allowed us to derive the properties of the dust emission, the molecular outflow, and the dense protostellar envelope. By adding this source to the sample of intermediate-mass protostars with outflows, we compare their properties and evolution with those of lower mass counterparts. Results. The 2.7mm continuum emission has been resolved into three sources, labeled OVRO 1, OVRO 2, and OVRO 3. Two of them, OVRO 1 and OVRO 2, have also been detected at 7 mm. OVRO 3, which is located close to the C18O emission peak, could be associated with IRAS 20050+2720. The mass of the sources, estimated from the dust continuum emission, is 6.5 Msun for OVRO 1, 1.8 Msun for OVRO 2, and 1.3 Msun for OVRO 3. The CO(1-0) emission traces two bipolar outflows within the OVRO field of view, a roughly east-west bipolar outflow, labeled A, driven by the intermediate-mass source OVRO 1, and a northeast-southwest bipolar outflow, labeled B, probably powered by a YSO engulfed in the circumstellar envelope surrounding OVRO 1.Comment: 13 pages, 8 figures, 5 tables. Accepted for publication by A&

Síndrome constitucional y anemia como debut de vasculitis en un adulto mayor. Reporte de caso

Introduction: Vasculitis comprises a group of often serious diseases that have an unspecific onset and a late diagnosis. The following report describes a case of vasculitis that may lead to considering this disorder as a differential diagnosis from the beginning of the care process to ensure a comprehensive approach and early treatment initiation that reduce associated morbidity and mortality and improve the success rate of treatments. Case presentation: A 77-year-old female, with a 2-year history of arterial hypertension was admitted to the emergency department of a secondary care center for having experienced symptoms of asthenia, fever, hyporexia and weight loss for a month. The patient was hospitalized for further testing and, given the findings, a possible bacterial translocation secondary to intestinal neoplasm was suspected. Empirical antibiotic treatment was started, but her condition continued to worsen. Complementary tests were performed, although they were not conclusive.  Due to the persistence of fever, kidney failure and anemia, a kidney biopsy was performed, revealing arterial vessel with fibrinoid necrosis and associated polymorphonuclear infiltrates, clear signs of an active vasculitis of the microscopic polyangiitis type. Several lines of treatment were used, but the patient evolved unfavorably and died. Conclusions: The presentation of this unusual case intends to contribute to the early diagnosis of this disorder by making medical staff aware of the possibility of considering it when symptoms suggest other diseases, or even when nonspecific symptoms such as anemia and weight loss occur.Introducción. Las vasculitis son enfermedades graves que suelen tener un debut muy inespecífico y un diagnóstico tardío, lo que implica una alta tasa de fracaso terapéutico. Se presenta un caso de vasculitis que puede contribuir a considerar esta enfermedad como parte del diagnóstico diferencial desde las primeras etapas del proceso de atención para garantizar un abordaje integral y un inicio temprano del tratamiento, lo que reduciría la morbimortalidad asociada a estas entidades y mejoraría la tasa de éxito de los tratamientos. Presentación del caso. Mujer caucásica de 77 años que como único antecedente presentaba hipertensión arterial de dos años de evolución y quien consultó al servicio de urgencias de una institución de segundo nivel por cuadro clínico de un mes de evolución consistente en astenia, febrícula, hiporexia y pérdida de peso. La paciente fue hospitalizada para completar la historia clínica y dados los hallazgos se sospechó de una posible translocación bacteriana secundaria a una neoplasia intestinal y se inició cobertura antibiótica empírica, pero su condición seguía empeorando. Se realizaron pruebas complementarias que no arrojaron resultados concluyentes; ante la persistencia de la fiebre, la insuficiencia renal y la anemia, se realizó una biopsia de riñón que mostró vaso arterial con necrosis fibrinoide e infiltrados de polimorfonucleares asociados, claros signos de una vasculitis activa del tipo poliangeítis microscópica. Se instauró el tratamiento indicado pero la paciente tuvo una evolución desfavorable y falleció. Conclusiones. La exposición de este caso inusual contribuye a que los profesionales de la salud consideren el diagnóstico de vasculitis desde el inicio de la atención, aun cuando la sintomatología sugiere otras patologías o incluso cuando se presentan síntomas tan inespecíficos como anemia y pérdida de peso, ya que esto ayudará a establecer un diagnóstico temprano