A high-resolution H I study of the interstellar medium local to HD 193793

A 2° field centered at the optical position of the Wolf-Rayet (WR) star HD 193793 (≡ WR 140) was surveyed in the H I 21 cm line and in the 1420 MHz radio continuum, using the Dominion Radio Astrophysical Observatory interferometer. The aim of this observations was to look for evidence of an interaction between the WR star and its local interstellar medium (ISM). Our H I data displays a large oval minimum at a velocity of Vsys ≃ -12 km s-1, close to the optical position of HD 193793. We believe this H I void was created by WR 140 and its massive companion (HD 193793 is a member of a well-known binary system). The major axis of the H I void is ∼11.5 pc and its axial ratio, the ratio of major to minor axis, is ∼1.4. This structure is observable over a velocity range of around 11 km s-1. The H I minimum appears surrounded by a clumpy shell of H I in emission that has a total mass of neutral hydrogen of MH I ∼ 1300 solar masses. The kinematical distance corresponding to a local standard of rest velocity of -12 km s-1 is approximately 5.4 kpc, which disagrees with the distance of HD 193793, namely, around 1 kpc. Therefore, it is concluded that the H I bubble was blown in an ISM having nonnegligible peculiar motions. Hipparcos proper-motion measurements indicate that HD 193793 has a tangential velocity of 28 ± 3 km s-1 along the major axis of one of the H I minima detected in the interior of the main H I cavity. To reconcile this motion with the physical size of the H I structure blown by the winds of the binary system, it is concluded that such tangential velocity was acquired by the system a short while ago, namely, ∼1.3 × 105 yr. Maps from the IRAS database show a large-scale IR feature, with good spatial correlation with the H I shell surrounding the main H I void. We believe the emission from the IR shell arises from dust grains heated by the energetic stellar continuum photons emitted by the stellar objects.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Molecular observations of the environs of the oxygen W-R star WR 102

Mediante observaciones de 12CO (J=1→ 0) llevadas a cabo en la direcci´on de la estrella WR 102 se han encontrado dos concentraciones moleculares muy probablemente vinculadas a la misma. Una se encuentra a una velocidad radial de 24 km s −1 y la otra a 13 km s −1 . La primera posee una clara correlaci´on morfol´ogica con la fuente de continuo (G2.4+1.4) relacionada con WR 102 mientras que la segunda se observa proyectada sobre la misma. Esta ultima ´ representar´ıa material molecular acelerado por los fuertes vientos estelares de WR 102. La masa molecular involucrada en ambas estructuras es del orden de 760 masas solares.12CO (J=1→ 0) observations towards WR 102 and its associated nebula (G2.4+1.4) revealed the presence of two molecular concentrations associated with them. The radial velocity of these concentrations are 24 and 13 km s −1 , respectively. The former represents the molecular cloud envisaged in the model of Dopita and Lozinskaya, whilst the latter may be molecular gas accelerated towards the observer by the strong stellar winds. The total amount of molecular gas in this complex is about 760 solar masses.Fil: Arnal, Edmundo Marcelo. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomia; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

Molecular observations of the environs of the oxygen W-R star WR 102

Mediante observaciones de 12CO (J=1→ 0) llevadas a cabo en la dirección de la estrella WR 102 se han encontrado dos concentraciones moleculares muy probablemente vinculadas a la misma. Una se encuentra a una velocidad radial de 24 km s −1 y la otra a 13 km s −1 . La primera posee una clara correlación morfológica con la fuente de continuo (G2.4+1.4) relacionada con WR 102 mientras que la segunda se observa proyectada sobre la misma. Esta última representaría material molecular acelerado por los fuertes vientos estelares de WR 102. La masa molecular involucrada en ambas estructuras es del órden de 760 masas solares.12CO (J=1→ 0) observations towards WR 102 and its associated nebula (G2.4+1.4) revealed the presence of two molecular concentrations associated with them. The radial velocity of these concentrations are 24 and 13 km s −1 , respectively. The former represents the molecular cloud envisaged in the model of Dopita and Lozinskaya, whilst the latter may be molecular gas accelerated towards the observer by the strong stellar winds. The total amount of molecular gas in this complex is about 760 solar masses.Facultad de Ciencias Astronómicas y Geofísica

A 12CO (J = 1 -> 0) study towards the Ara OB1 region

Intermediate angular resolution (HPBW = 8. 0 7) carbon monoxide (12CO J = 1→0) line observations towards the OB association Ara OB1 are reported. The molecular line observations cover an area of 2. ◦75 × 3. ◦00, and disclose a rich and complex distribution of the molecular line emission. The molecular features likely to be associated with the OB-association Ara OB1 span the velocity range from −28 to −20 km s−1. The most negative radial velocities are observed along NGC 6188 (≡Rim nebula). This nebula marks the interface between the H region RCW 108 and the highly absorbing molecular material located westwards of the ionised region. The dominant CO structures, labeled E and F, have a radial velocity of about −23.5 and −21.8 km s−1, respectively. The former harbours a bright optical knot, the infrared cluster RCW-108 and the strong IRAS source 16362−4845. IRAS point sources are also seen in projection onto 12CO concentrations F and H. This may indicate that the star forming process is a widespread phenomenon in this molecular complex. Extended continuum emission, having a high degree of spatial correlation with both the infrared and molecular emission, is observed in the region. We believe that this emission, thermal in nature, arises from the ionised surface layers of the molecular complex. The ionising agents are the high mass stars of NGC 6193, the nucleus of Ara OB1. The total amount of molecular gas related to Ara OB1 is about ∼1.4×104 M .Fil: Arnal, Edmundo Marcelo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: May, J.. Universidad de Chile; ChileFil: Romero, Gisela Andrea. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentin

An Effelsberg HI study of the ISM around WR 126, WR 154 and WR 155

The neutral hydrogen distribution has been studied in the direction of three Galactic Wolf-Rayet (WR) stars using the 100 m Effelsberg radio telescope. Cavities in the HI distribution, regions of low HI emissivity, are observed over a 8-9 km s-1 velocity range for WR 126 (≡ST 2), WR 154 (≡HD 213049) and WR 155 (≡HD 214419). These minima are interpreted as the observable 21-cm HI line counterpart of interstellar bubbles created by the winds of the WR stars and their progenitors. The HI cavities are elongated structures depicting an axial ratio ranging from 1.3 (WR 155) to 3 (WR 126). The WR stars are always eccentric with respect to either the geometric centre of the HI cavity or the absolute minimum inside it. This offset ranges from 50% to 80% of the HI hole's minor axis. The major axis of these structures range from 13 (WR 155) to 27 pc (WR 126), while the missing HI mass amounts to 45-50 M⊙ (WR 126), 60 M⊙ (WR 155) and 85 M⊙ (WR 154).Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Gas molecular en la nebulosa anillo alrededor de WR 16

Using NANTEN 12CO (J=1→ 0) observations, the distribution of the molecular gas towards the multiple ring nebula sorrounding the star WR 16 has been analysed. Two striking features associated with the star and the nebula, respectively, were identified. One of them, the external one, is interstellar molecular gas which has been wind shaped in an early stage of the star. The internal feature is only noticed in a very small velocity range and has probably a stellar origin. Physical parameters have been calculated and kinematical models have been constructed in order to explain the physical link between these features and the nebula.En este artículo se presenta un estudio del gas molecular llevado a cabo en la nebulosa anillo múltiple alrededor de la estrella WR 16, usando observaciones de la línea (J=1→ 0) del 12CO obtenidas con el radiotelescopio NANTEN. Se encontraron dos estructuras moleculares cuya morfología las asocia a la nebulosa. La estructura más externa podría haberse originado como resultado de la interacción con los vientos de la estrella en una etapa temprana de su evolución. La estructura interna parece estar formada por gas molecular originado en la atmósfera de la estrella en una etapa intermedia de su evolución y sólo es visible en un rango muy peque˜no de velocidad radial. Para estas estructuras, se calcularon algunos parámetros físicos y se construyó un modelo cinemático que podría explicar su morfología y su relación con la estrella y la nebulosa.Fil: Duronea, Nicolas Urbano. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Arnal, Edmundo Marcelo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

HI en cúmulos galácticos

Nueve cúmulos galácticos, la mayoría con |b| > 15 °, fueron estudiados en la línea de 1420 MHz. Cotas superiores para la masa y densidad se pueden dar para la totalidad de los objetos.Asociación Argentina de Astronomí

12CO (J=1-0) images of the surroundings of three galactic Wolf-Rayet stars

We present 12CO (J=1-0) images of the surroundings of three galactic Wolf-Rayet stars. As part of a program aim to study the interaction of massive stars with their enviroments, we have begun a study of the distribution of molecular gas around Wolf-Rayet stars. The carbon monoxide database is combined with both far infrared (MSX and IRAS) and radio continuum observations at 2.4 and 5.0 GHz. A few cavities and arc-shaped structures were found likely to be associated with the Wolf-Rayet stars.Fil: Duronea, Nicolas Urbano. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Arnal, Edmundo Marcelo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentin

A high-resolution H I study of the interstellar medium local to HD 193793

A 2° field centered at the optical position of the Wolf-Rayet (WR) star HD 193793 (≡ WR 140) was surveyed in the H I 21 cm line and in the 1420 MHz radio continuum, using the Dominion Radio Astrophysical Observatory interferometer. The aim of this observations was to look for evidence of an interaction between the WR star and its local interstellar medium (ISM). Our H I data displays a large oval minimum at a velocity of Vsys ≃ -12 km s-1, close to the optical position of HD 193793. We believe this H I void was created by WR 140 and its massive companion (HD 193793 is a member of a well-known binary system). The major axis of the H I void is ∼11.5 pc and its axial ratio, the ratio of major to minor axis, is ∼1.4. This structure is observable over a velocity range of around 11 km s-1. The H I minimum appears surrounded by a clumpy shell of H I in emission that has a total mass of neutral hydrogen of MH I ∼ 1300 solar masses. The kinematical distance corresponding to a local standard of rest velocity of -12 km s-1 is approximately 5.4 kpc, which disagrees with the distance of HD 193793, namely, around 1 kpc. Therefore, it is concluded that the H I bubble was blown in an ISM having nonnegligible peculiar motions. Hipparcos proper-motion measurements indicate that HD 193793 has a tangential velocity of 28 ± 3 km s-1 along the major axis of one of the H I minima detected in the interior of the main H I cavity. To reconcile this motion with the physical size of the H I structure blown by the winds of the binary system, it is concluded that such tangential velocity was acquired by the system a short while ago, namely, ∼1.3 × 105 yr. Maps from the IRAS database show a large-scale IR feature, with good spatial correlation with the H I shell surrounding the main H I void. We believe the emission from the IR shell arises from dust grains heated by the energetic stellar continuum photons emitted by the stellar objects.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Vinculación física entre super cáscaras de hidrógeno neutro y formación estelar reciente

Las super cáscaras de Hi (SCHi) podrían haber sido formadas por vientos estelares y/o explosiones de supernovas. Con tiempos dinámicos de vida del orden de decenas de millones de años, las estructuras de mayor tamaño sobreviven a las estrellas de gran masa que pudieran haberle dado origen. Por este motivo, las SCHi podrían ser usadas como registros fósiles para estudiar los efectos de formación estelar en la Vía Láctea. Por otra parte, durante su evolución, las SCHi podrían dar origen a nuevas generaciones de estrellas. En este trabajo investigamos la posible vinculación física entre la asociación OB Centaurus OB1 y la SCHi GSH305+01-24 del catálogo de McClure-Griffiths et al. (2002). De nuestro estudio concluimos que GSH305+01-24 no representa una estructura física real. Su estructura resulta mejor representada por dos grandes cáscaras no vinculadas entre sí. En este contexto, no resulta claro el rol que pueda haber jugado Cen OB1 en la creación de una de estas cáscaras de Hi.Many of the known galactic Hi supershells may have been formed by the combined effects of stellar winds and supernovae explosions. Having most of them dynamic lifetimes of a few times 107 yr, these huge structures are likely to outlive the stars that gave rise to them. Hence, these galactic Hi supershells may be used as fossil records of the Milky Way star formation history. Furthermore, along their evolution galactic Hi supershells may trigger star formation. In this paper we analyze the genetic link put forward by McClure-Griffiths et al. (2002) between the OB association Cen OB1 and the galactic Hi supershells GSH305+01-24. From own study we conclude that GSH305+01-24 may not represent a real physical structure. Instead, we believe that their structure is best represented by two unrelated huge Hi shells. The role played by Cen OB1 in powering one of these Hi shells is unclear for the time beeing.Fil: Corti, Mariela Alejandra. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomia; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Arnal, Edmundo Marcelo. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomia; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin