Revista mexicana de astronomía y astrofísica

http://www.scielo.org.mx/scielo.php?script=sci_issues&pid=0185-1101&lng=pt&nrm=iso

List of Papers (Total 45)

In search of a radio counterpart for the ultraluminous X-ray source at the nucleus of M33

We present an analysis of radio continuum observations of the nucleus of the spiral galaxy M33, taken from the Very Large Array archives. Most of these observations were made with high angular resolution (≤1") at different epochs and we have used them to search for radio emission associated with the ultraluminous X-ray (ULX) source at the center of M33. At 20 cm, with an angular...

CCD photometry of the RR Lyrae stars in NGC 4147

We report the results of CCD V a nd R photometry of the RR Lyrae stars known in NGC 4147. The periodicities of most variables are revised and new ephemerides are calculated. The Blazhko effect has been detected in V2 and V6. Three previously reported variables; V5, V9, and V15 are found to be non-variable. A new variable V18 was discovered with a period of 0.49205 days and an...

Hydrodynamical interaction between an accretion flow and a stellar wind

Molecular clouds in the interstellar medium suffer gravitational instabilities that lead to the formation of one or multiple stars. A recently formed star inside a cold cloud communicates its gravitational force to the surrounding environment and soon an accretion flow falling into the star develops. After their formation, all stars soon eject a wind of gas that interacts with...

Nebulous objects in the Southern Hemisphere

We have inspected plates of the Southern Hemisphere with the purpose of finding previously unreported nebulous objects. We found 93 objects, of which 62 are associated with IRAS point sources. Some of these objects look like Herbig-Haro objects, while others are cometary nebulae, tight groups of red dwarf stars, and objects resembling small regions of star formation.

Herbig-Haro jets from sources in elliptical orbits

In this paper, we study the kinematical evolution of a HH (Herbig-Haro) jet produced in a binary stellar system in which the jet source is movingin an elliptical orbit around a stellar companion. An anlytical model describing the motion of a ballistic jet is presented, showing diverse morphologies obtained for dierent ellipticities of the orbital motion. In addition, we have...

Low-resolution spectroscopy and uvby-β photometry of selected stars in Haffner 18

We present MK spectral types of a sample of selected (bright) stars associated with the galactic cluster Haffner 18 in Puppis. They were obtained from low-resolution (λ/Δλ = 1720) spectra by Hα slit spectroscopy. Some of the selected stars were also observed photoelectrically in the uvby-β system. Our spectroscopic data show that over 1/4 of the estimated 50 star members of the...

WWW database of models of accretion disks irradiated by the central star

We announce the release of a catalog of physical models of irradiated accretion disks around young stars based on the modelling techniques by D'Alessio et al. The WWW catalog includes ~ 3000 disk models for different central stars, disk sizes, inclinations, dust contents and mass accretion rates. For any of them, radial profiles of disk physical parameters and synthetic spectral...

Two scenarios for the formation of cuspy density profiles in elliptical galaxies

We address the formation of cuspy density profiles, through N-body simulations, in two complementary scenarios: (1) a cold gravitational collapse around a preexisting supermassive black hole, and (2) an adiabatic growth of a central black hole in a relaxed stellar system obtained from a cold gravitational collapse. Both models lead to a density profile, ργ, with a similar power...

Shadows and photoevaporated flows from neutral clumps exposed to two ionizing sources

Neutral clumps immersed in H II regions are frequently found in star formation regions. We investigate here the formation of tails of neutral gas, which are not reached by the direct ionizing flux coming from two massive stars, using both an analytical approximation that allows us to estimate the shadow geometry behind the clumps for different initial geometric configurations...

Preservation of Cuspy Profiles in Disk Galaxy Mergers

We carried out three self-consistent N-body simulations of galaxy mergers, with a cuspy dark matter profile, in order to study if the inner dark density slope is preserved in the remnants. In these simulations the progenitors include both a stellar disk and an intrinsic angular momentum for the halos, unlike previous similar studies. The mass-ratios of progenitor galaxies are...

Mid-Infrared Observations of V838 MON

We present 8-13 narrow-band photometry of the peculiar star V838 Mon in 2002 September. Our spectrum is consistent with a simple power-law spectrum, although a spectrum with excess emission between 9 and 12 provides a better fit.

The Saturnian G ring: a short note about its formation

In this paper we examine the formation of the Saturnian G ring by considering the motion of dust launched from the surface of Aegaeon. Those particles are ejected from the satellite surface by impacts between the interplanetary meteoroids and the satellite. The gravito-electrodynamic model we use involves only two forces (gravitational and Lorentz), and its solutions show the...

The cosmic ray and the 10.7 cm flux variations during solar cycles 19-23

The cosmic ray flux (CRF) and 10.7 cm flux (F10.7) are studied for solar cycles 19-23. The cross-correlations show longer time-dependence at odd than at even cycles. A shift of the maximum at the histograms of CRF1 /F10.71 (the ratios of normalized values), does not depend on the polarity of the cycle. The behavior of CRF1 vs F10.71 differs for odd and even cycles and also for...

The present and future of planetary nebula research: A white paper by the IAU planetary nebula working group

We present a summary of current research on planetary nebulae and their central stars, and related subjects such as atomic processes in ionized nebulae, AGB and post-AGB evolution. Future advances are discussed that will be essential to substantial improvements in our knowledge in the field.

Optical polarization of solar type stars with debris disks

We report optical aperture polarimetry for 34 southern hemisphere main-sequence stars with debris disks, in addition to 54 stars without evidence of disk. These sets of stars are combined with another set of 109 stars from the northern hemisphere, obtained from the literature, to build two samples of 51 and 97 solar-type stars with and without debris disks. The distributions of...

The 2013 release of cloudy

This is a summary of the 2013 release of the plasma simulation code Cloudy. Cloudy models the ionization, chemical, and thermal state of material that may be exposed to an external radiation field or other source of heating, and predicts observables such as emission and absorption spectra. It works in terms of elementary processes, so is not limited to any particular temperature...

New orbits for Comets C/1960 M1 (Humason), C/1980 E1 (Bowell), and musings on extrasolar comets

New orbits are calculated for Comets Humason (C/1960 M1) and Bowell (C/1980 E1). Humason's orbit is based on 34 observation made over 348 days and Bowell's on 203 observations made over nearly eight years. Both comets have hyperbolic orbits. Backwards integrations indicate that both comets had originally highly elliptical orbits which changed to hyperbolas by the injection o...

A new analytic approximation to the isothermal, self-gravitating sphere

We derive a new analytic prescription for the density of the non-singular, isothermal, self-gravitating sphere. The proposed prescription gives the density stratification for all radii with a maximum error of ≈1%. This is an improvement over previous prescriptions, which only gave such an accuracy over limited radial domains.

What Do the Star Formation Histories of Galaxies Tell Us About the Starburst-AGN Connection?

We have determined the normal star formation histories (SFHs) for narrow emission line galaxies classified as star forming galaxies (SFGs), transition type objects (TOs), Seyfert 2s (Sy2s) and LINERs. The SFH varied with the activity type, following the mass of the galaxies and the importance of their bulge: LINERs reside in massive early-type galaxies, Sy2s and TOs in...

Open slit echelle spectroscopy of planetary nebula M 1-9

Optical spectroscopy of the entire planetary nebula M 1-9, reveals pronounced density variations, a temperature distribution where Te(N+) is larger than Te(0+2) and abundances indicating that it is a halo planetary nebulae, an association supported by it is very large radial velocity and distance to the galactic plane. The ionized mass is between 0.1 and 0.4 Mʘ. A uniform density...

Discovery of New Faint Northern Galactic Planetary Nebulae

We present the discovery of 6 nebular objects made by amateur astronomers. Four of these discoveries are clearly planetary nebulae (PNe), one is a possible PN, and another is a likely H II region. The bipolar nebula Ou4 presents the largest angular extent ever found: over one degree on the sky! We consider various scenarios that could explain such a nebula. Ou4 could be one of...

New Analytic Results for Poissonian and non-Poissonian Statistics of Cosmic Voids

Stereology allows shifting from the 3D distribution of the volumes of Poisso-nian Voronoi Diagrams to their 2D cross-sections. The basic assumption is that the 3D statistics of the volumes of the voids in the local Universe has a distribution function of the gamma-type. The standard rule of conversion from 3D volumes to 2D circles, adopting the standard rules of stereology...