RevMexAA: Abstracts of Accepted Papers for Volume 47 Number 1


February 4, 2011

2011: February January

2010: December November September



February 2011


HII Regions and the Protosolar Helium, Carbon, and Oxygen Abundances in the context of Galactic Chemical Evolution

L. Carigi and M. Peimbert

Instituto de Astronomía
Universidad Nacional Autónoma de México, Mexico

carigi@astroscu.unam.mx

Received: 2010 November 18
Accepted: 2011 February 3

Abstract: We present chemical evolution models of the Galactic disk with different Z-dependent yields. We find that a moderate mass loss rate for massive stars of solar metallicity produces an excellent fit to the observed C/H and C/O gradients of the Galactic disk. The best model also fits: the H, He, C, and O abundances derived from recombination lines of M17, the protosolar abundances, and the C/O-O/H, C/Fe-Fe/H, and O/Fe-Fe/H relations derived from solar vicinity stars. The agreement of the model with the protosolar abundances implies that the Sun originated at a galactocentric distance similar to the one it has. Our model for r = 3 kpc implies that a fraction of the stars in the direction of the bulge formed in the inner disc. We obtain a good agreement between our model and the C/O versus O/H relationship derived from extragalactic HII regions in spiral galaxies.



January 2011


Mid- and Far-Infrared Photometry of Galactic Planetary Nebulae with the AKARI All-Sky Survey

J. P. Phillips and R.A. Marquez-Lugo

Instituto de Astronomía y Meteorología, Universidad de Guadalajara, Mexico

jpp@astro.iam.udg.mx

Received: 2010 December 14
Accepted: 2011 January 28

Abstract: We provide mid- and far-infrared photometry of 857 Galactic planetary nebulae (PNe) using data derived from the AKARI All-Sky Survey. These include fluxes at 9 and 18 μm obtained with the Infrared Camera (IRC), and at 65, 90, 140 and 160 μm using the far-Infrared Surveyor (FIS). It is noted that the IR luminosities of the youngest PNe are comparable to the total luminosities of the central stars, and subsequently decline to ~5×102 L where D > 0.08 pc. This is consistent with an evolution of PNe dust opacities, and appreciable absorption in young and proto-PNe. We also note that there is little evidence for the evolution in IR/radio flux ratios suggested by previous authors. The fall-off of dust temperatures with increasing nebular diameter is similar to that determined in previous studies, whilst levels of Lyα heating are < 0.5 of the total energy budget of the grains. There appears to be an evolution in the infrared excess (IRE) as nebulae expand, with the largest values occurring in the most compact PN.



Recalibrated turbulence profiles at San Pedro Mártir

R. Avila,1,2 L. J. Sánchez,3 I. Cruz-González,3 E. Carrasco,4 and V. M. Castaño5,6

1Centro de Física Aplicada y Tecnología Avanzada, UNAM, Mexico
2On leave from Centro de Radioastronomía y Astrofísica, UNAM, Mexico
3Instituto de Astronomía, UNAM, Mexico
4Instituto Nacional de Astrofísica, Óptica y Electrónica, Mexico
5Universidad Autónoma de Querétaro, Campus Cerro de las Campanas, Mexico
6On sabatical leave from Centro de Física Aplicada y Tecnología Avanzada, UNAM, Mexico

r.avila@crya.unam.mx

Received: 2010 December 1
Accepted: 2011 January 21

Abstract: The calibration of optical turbulence (CN2) profiles measured with the generalized SCIDAR technique has been recently reviewed and corrected by Avila & Cuevas (2009). Based on that work, here we present the correction of all the CN2 profiles measured with a generalized SCIDAR at the Observatorio Astronómico Nacional of San Pedro Mártir. The median corrected CN2 profile conserves its overall vertical shape. The altitude-averaged ratio of the corrected median CN2 values over the uncorrected ones equals 0.87. The corrected median value of seeing at the site is 0.′′68 ± 0.′′03, 4.2% lower than the median value obtained with the uncorrected profiles. The median values of the seeing produced by turbulence in the first 2 km above the 1.5 m and the 2.1 m telescopes decrease by 15.8% and 13.6%, respectively. The corrected isoplanatic angle has a median value of 1.′′96 ± 0.′′04.



UBVR polarimetry of high-galactic latitude carbon stars

J. M. López and D. Hiriart

Instituto de Astronomía
Universidad Nacional Autónoma de México, Ensenada, B.C., México

jmlopez@astrosen.unam.mx

Received: 2010 October 20
Accepted: 2011 January 17

Abstract: We present UBVR polarimetry and photometry obtained over a period of one year of eight high-galactic latitude carbon stars: V Hya, CZ Hya, R For, R Lep, Y Cvn, T Dra, RV Aqr, and RT Cap. The observed polarization is the highest in the U band and highly variable with time. Similarly, the polarization in the B band is highly variable but the values are always lower than those in U band. The origin and variability of the linear polarization in these bands may be explained as dispersion of radiation from the central star at the inner regions of the circumstellar envelope where grains and molecules are created, destroyed, and stirred by shock waves.



Planetary nebulae in the inner Milky Way II: the Bulge-Disk transition

O. Cavichia, R. D. D. Costa, and W. J. Maciel

Instituto de Astronomia, Geofísica e Ciências Atmosféricas
Universidade de São Paulo, Brazil

cavichia@astro.iag.usp.br

Received: 2010 November 29
Accepted: 2011 January 14

Abstract: In this work, a sample of planetary nebulae located in the inner-disk and bulge of the Galaxy is used in order to find the galactocentric distance which better separates these two populations, from the point of view of abundances. Statistical distance scales were used to study the distribution of abundances across the disk-bulge interface. A Kolmogorov-Smirnov test was used to find the distance in which the chemical properties of these regions better separate.

The results of the statistical analysis indicate that, on the average, the inner population has lower abundances than the outer. Additionally, for the α-elements abundances, the inner population does not follow the disk radial gradient towards the galactic center. Based on our results, we suggest a bulge-disk interface at 1.5 kpc, marking the transition between the bulge and inner-disk of the Galaxy, as defined by the intermediate mass population.



December 2010


Mid-Infrared Observations of Planetary Nebulae detected in the GLIMPSE 3D Survey

J. A. Quino-Mendoza, J. P. Phillips, and G. Ramos-Larios

Instituto de Astronomía y Meteorología, Universidad de Guadalajara, México

jpp@astro.iam.udg.mx

Received: 2010 September 23
Accepted: 2010 December 13

Abstract: We present mapping, profiles and photometry for 24 planetary nebulae (PNe) detected in the GLIMPSE 3D mid-infrared (MIR) survey of the Galactic plane. The PNe show many of the properties observed in previous studies of these sources, including evidence for longer wave emission from outside of the ionised zones, a likely consequence of emission from polycyclic aromatic hydrocarbons (PAHs) within the nebular photo-dissociation regimes (PDRs). We also note variations in 5.8μm/4.5μm and 8.0μm/4.5μm flux ratios with distance from the nuclei; present evidence for enhanced MIR emission in the halos of the sources; and note evidence for variations in colour with nebular evolution.



November 2010


The Parker instability in axisymmetric filaments: final equilibria with longitudinal magnetic field

F. J. Sánchez-Salcedo1 and A. Santillán2

1Instituto de Astronomía, Universidad Nacional Autónoma de México, Mexico
2Cómputo Aplicado-DGSCA, Universidad Nacional Autónoma de México, Mexico

jsanchez@astroscu.unam.mx

Received: 2010 August 4
Accepted: 2010 November 18

Abstract: We study the final equilibrium states of the Parker instability arising from an initially unstable cylindrical equilibrium configuration of gas in the presence of a radial gravitational field and a longitudinal magnetic field. The aim of this work is to compare the properties of the nonlinear final equilibria with those found in a system with Cartesian geometry. Maps of the density and magnetic field lines, when the strength of the gravitational field is constant, are given in both geometries. We find that the magnetic buoyancy and the drainage of gas along field lines are less efficient under axial symmetry than in a Cartesian atmosphere. As a consequence, the column density enhancement arising in gas condensations in the axially-symmetric model is smaller than in Cartesian geometry. The magnetic-to-gas pressure ratio in the final equilibrium state takes more extreme values in the Cartesian model. Models with non-uniform radial gravity are also discussed.



September 2010


FUNDPAR: A program for Deriving Fundamental Parameters from Equivalent Widths

C. Saffe

Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (ICATE), San Juan, Argentina

csaffe@icate-conicet.gob.ar

Received: 2010 July 2
Accepted: 2010 September 14

Abstract: We implemented a fortran code that determine fundamental parameters of solar type stars from a list of Fe line equivalent widths. The solution should verify 3 conditions in the standard method: ionization equilibrium, excitation equilibrium and independence between metallicity and equivalent widths. We added the condition that the input metallicity of the model atmosphere should be similar to the output metallicity derived with equivalent widths. Solar-scaled Kurucz model atmospheres with NEWODF opacities are calculated with an independent program. Parameter files control different details, such as the mixing-length parameter, the overshooting, the damping of the lines and the weight factors in the definition of the χ2 function. FUNDPAR derive the uncertainties following 2 methods: the criteria of Gonzalez & Vanture (1998) and the dispersion using the χ2 function. The code use the 2009 version of the MOOG program. The results derived with FUNDPAR are in agreement with previous determinations in the literature. In particular we obtained the fundamental parameters of 58 exoplanet host stars. The program is freely available from the web http://icate-conicet.gob.ar/saffe/fundpar/.