Características físicas comparativas de nebulosas planetarias con estrellas centrales ricas y pobres en hidrógeno /

Tesis (Doctor en Astronomia)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2009.Con el objeto de aumentar el número de estrellas centrales de nebulosas planetarias con tipo espectral determinado, y buscar posibles diferencias estadísticas que nos permitan caracterizar los núcleos ricos de los pobres en hidrógeno, es que iniciamos un estudio observacional de estos objetos. Para esto estudiamos una muestra homogénea propia de más de setenta NP. Los resultados mas importantes que se consiguieron son los siguientes: Incrementamos un 19% el número conocido de estos objetos. Y observamos que las estrellas deficientes en hidrógeno poseen nebulosas de mayor densidad, mayor excitación, mayor abundancia de oxígeno y son de tamaño angular relativamente pequeño. Estos resultados son razonablemente consistentes con el modelo de “born-again” para explicar la ausencia de hidrógeno en estas estrellas.Walter Alfredo Weidmann

Correlaciones entre la morfología de nebulosas planetarias y el tipo espectral de sus estrellas centrales

The mechanisms by which an ordinary star gives rise to a planetary nebula (PN) remain uncertain. The reason why central stars of PNe have both hydrogen-rich and hydrogen-poor atmospheres is also unknown. Certainly the mechanisms that trigger mass loss are related to the hydrogen abundance of the remnant star. On the other hand, the morphology displayed by PNe is necessarily related to the mass-loss mechanism. We have found that the hydrogen abundance in the central stars of PNe atmosphere does not correlate with PN morphology. We also show that a similar distribution of morphologies is observed for different evolutionary stages of CSPNe, suggesting that morphology does not change with PN age. Finally we present evidence suggesting that binary cores do not correlate with NPe of bipolar morphology.Fil: Mudrik, Armando. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Antropología de Córdoba. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Instituto de Antropología de Córdoba; ArgentinaFil: Weidmann, Walter Alfredo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Rotation curves and dynamical masses of MaNGA barred galaxies

In this paper we analyse a sample of 46 barred galaxies of MaNGA. Our goal is to investigate the stellar kinematics of these galaxies and obtain their rotation curves. Additionally, we aim to derive the total stellar and dynamical masses, as well as the maximum rotation velocity, in order to examine their distributions and scaling relations. Using the Pipe3D dataproducts publicly available we obtained the rotation curves, which were fitted considering two components of an axisymmetric Miyamoto–Nagai gravitational potential. We found a wide range of the maximum rotation velocities (117–340 km s−1), with a mean value of 200 km s−1. In addition we found that the total stellar and dynamical masses are in the range of log(Mstar/M☉) = 10.1−11.5, with a mean value of log(Mstar/M☉) = 10.8, and log(Mdyn/M☉) = 10.4−12.0, with a mean value of log(Mdyn/M☉) = 11.1, respectively. We found a strong correlation between dynamical mass and maximum velocity, between maximum velocity and magnitude, and between stellar mass and maximum velocity. According to these results, barred galaxies exhibit similar behaviour to that of normal spiral galaxies with respect to these relations, as well as in terms of the distribution of their dynamical mass and maximum rotation velocity. However, we found that the distribution of stellar masses of barred galaxies is statistically different from other samples including non-barred galaxies. Finally, analysing the galaxies that show nuclear activity, we find no difference with the rotation curves of normal galaxies.Fil: Schmidt, Eduardo Osvaldo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Mast, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Gaspar, Gaia. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Weidmann, Walter Alfredo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Hunting young white dwarfs at the Center of Planetary Nebulae

We present Gemini-South observations of nine faint and extended planetary nebulae (PNe). Using direct images taken with the spectrograph Gemini-South multi-object spectrograph (GMOS), we built the (u¢-g¢) versus (g¢-r¢) diagrams of the stars in the observed areas which allowed us to consider their geometrical positions and identify the probable central stars of the nebulae. Our stellar spectra of seven stars, also taken with GMOS, indicate that four (and probably two more) objects are white dwarfs of the DAO subtype. Moreover, the white dwarf status of the four stars is confirmed by the parameters Teff and log g derived with the help of theoretical stellar spectra. Given this evidence, we propose that these hot stars are the central ionizing sources of the nebulae. With this work we hope to help improve the current scarce statistics on central white dwarfs in PNe.Fil: Ahumada, Javier Alejandro. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Weidmann, Walter Alfredo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Miller Bertolami, Marcelo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Saker, Leila Yamila. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentin

Dust distribution in planetary nebulae

Context. Planetary nebulae (PN) have long been known to consist of gas, molecules and dust. The vast majority of the work in which properties of the dust of these objects are inferred were carried out with infrared observations. The downside with this technique is that infrared emision not only comes from dust. On the other hand, depending on the photometric band in which we are observing we will have information of the dust in a certain temperature range. In this sense, we use a technique that gives information about the dust, without nebular contamination, and regardless of its temperature.Aims. The primary objective is to present an atlas of images with the distribution of dust in planetary nebulae.Methods.We obtaing images in narrow-band filter centred on the nebular emission of the Balmer lines Hα and Hβ. These images were obtained with the moderate-aperture telescopes at the Estación Astrofísica de Bosque Alegre.We propose to combine these images toobtain the distribution of dust in galactic planetary nebulae. This technique allows to infer the distribution of the dust, independent ofits temperature. In addition this photometric data are combined with spetroscopic one, which strengthens our results.Results. We present original images of 29 bright south PN in which shows its dust spatial distribution. The data provided by this atlas represent the most extensive image surveys for PNe.Fil: Pignata, Rafael Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Weidmann, Walter Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Schmidt, Eduardo Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Mudrik, Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Mast, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentin

Asymmetric emission of the [OIII]λ5007 profile in narrow-line Seyfert 1 galaxies

Many active galactic nuclei (AGN) and particularly narrow-line Seyfert 1 (NLS1) galaxies, usually exhibit blueshifts and blue wings in several emission lines, which are mainly associated with outflows and strong winds. Although there is no clear evidence of the physical origin of the [OIII] blue wings, it has been suggested that they could be emitted from the inner parts of the narrow-line region (NLR). Aims. In order to study the radial velocity difference between the narrow component of Hβ and the core component of [OIII]λ5007 and the asymmetric emission of this forbidden line, we investigate a sample of NLS1 galaxies . One of the aims of this paper is to analyze the blue wings of the [OIII]λ5007 profiles and their relation with the central engine. Methods. We have obtained and studied medium-resolution spectra (190 km s−1 FWHM at Hβ) of a sample of 28 NLS1 galaxies in the optical range 4300-5200 Å. We performed Gaussian decomposition to the Hβ and [OIII]λλ4959,5007 emission profiles in order to study the distinct components of these lines. Results. A new blue outlier galaxy is found, in which the center of the core component of [OIII] is blueshifted by 405 km s−1 relative to the center of the narrow component of Hβ line. We confirmed a previously known correlation between the blueshift and the full width half maximum (FWHM) of the core component of [OIII]λ5007 line. We also corroborated the correlation between the latter and the velocity of the centroid of the blue wing. On the other hand, by studying the radial velocity difference between the blue end of the asymmetric emission and the centroid of the core component of [OIII], we found a correlation between it and the central black hole mass and, therefore, with the luminosity of the broad component of Hβ. Finally, we found a moderate correlation between the luminosity of the [OIII] blue wing and the black hole mass. Conclusions. These results suggest that the asymmetric emission of the [OIII] lines is related to the central engine, not only through the black hole but also in the intensity of the AGN, which is in agreement with previous results.Fil: Schmidt, Eduardo Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Oio, Gabriel Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Ferreiro, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Vega, Luis Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Weidmann, Walter Alfredo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

The interstellar medium and the massive stellar content towards the SNR G18.1-0.1 and neighbouring H II regions

We perform a multiwavelength study of the SNR G18.1-0.1 and nearby several H II regions (infrared dust bubbles N21 and N22, and the H II regions G018.149-00.283 and G18.197-00.181). Our goal is to provide observational evidence supporting the view that massive stars are usually born in clusters from the same molecular cloud, which then produce, along their evolution, different neighbouring objects such as H II regions, interstellar bubbles and supernova remnants (SNRs). We suggest that the objects analysed in this work belong to a same complex located at the distance of about 4 kpc. Using molecular data we inspected the interstellar medium towards this complex and from optical and X-ray observations we looked for OB-type stars in the region. Analysing public 13 CO J = 1-0 data we found several molecular structures very likely related to the H II region/SNR complex. We suggest that the molecular gas is very likely being swept and shaped by the expansion of the H II regions. From spectroscopic optical observations obtained with the 2.15-m telescope at CASLEO, Argentina, we discovered three O-type stars very likely exciting the bubbles N21 and N22, and an uncatalogued H II region northwards of bubble N22, respectively. Also we found four B0-5 stars, one towards the bubble N22 and the others within the H II region G18.149-0.283. By inspecting the Chandra Source Catalogue we found two-point X-ray sources and suggest that one of them is an early O-type star. Finally, we inspected the large-scale interstellar medium around this region. We discovered a big molecular shell of about 70 × 28 pc in which the analysed complex appears to be located in its southern border.Fil: Paron, Sergio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio(i); Argentina. Universidad de Buenos Aires; ArgentinaFil: Weidmann, Walter Alfredo. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba;Fil: Ortega, Martin Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio(i); ArgentinaFil: Albacete Colombo, Juan Facundo. Universidad Nacional del Comahue; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pichel, Ana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio(i); Argentin

Photometric and spectroscopic variations of the Be star HD 112999

Be objects are stars of B spectral type showing lines of the Balmer series in emission. The presence of these lines is attributed to the existence of an extended envelope, disk type, around them. Some stars are observed in both the Be and normal B-type spectroscopic states and they are known as transient Be stars. In this paper we show the analysis carried out on a new possible transient Be star, labelled HD 112999, using spectroscopic optical observations and photometric data.Instituto Argentino de RadioastronomíaFacultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Photometric and spectroscopic variations of the Be star HD 112999

Be objects are stars of B spectral type showing lines of the Balmer series in emission. The presence of these lines is attributed to the existence of an extended envelope, disk type, around them. Some stars are observed in both the Be and normal B-type spectroscopic states and they are known as transient Be stars. In this paper we show the analysis carried out on a new possible transient Be star, labelled HD 112999, using spectroscopic optical observations and photometric data.Instituto Argentino de RadioastronomíaFacultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Towards an improvement in the spectral description of central stars of planetary nebulae

Context. There are more than 3000 known Galactic planetary nebulae, but only 492 central stars of Galactic planetary nebulae (CSPN) have known spectral types. It is vital to increase this number in order to have reliable statistics, which will lead to an increase of our understanding of these amazing objects. Aims. We aim to contribute to the knowledge of central stars of planetary nebulae and stellar evolution. Methods. This observational study is based on Gemini Multi-Object Spectrographs (GMOS) and with the Intermediate Dispersion Spectrograph (IDS) at the Isaac Newton Telescope spectra of 78 CSPN. The objects were selected because they did not have any previous classification, or the present classification is ambiguous. These new high quality spectra allowed us to identify the key stellar lines for determining spectral classification in the Morgan-Keenan (MK) system. Results. We have acquired optical spectra of a large sample of CSPN. From the observed targets, 50 are classified here for the first time while for 28 the existing classifications have been improved. In seven objects we have identified a P-Cygni profile at the He I lines. Six of these CSPN are late O-Type. The vast majority of the stars in the sample exhibit an absorption-Type spectrum, and in one case we have found wide emission lines typical of [WR] stars. We give a complementary, and preliminary, classification criterion to obtain the sub-Type of the O(H)-Type CSPN. Finally, we give a more realistic value of the proportion of CSPN that are rich or poor in hydrogen.Instituto de Astrofísica de La Plat