RevMexAA: Abstracts of Accepted Papers for
Volume 46 Number 1
January 6, 2010
2010:
January
2009:
December
November
October
September
January 2010
A geometrical model for the catalogs of galaxies
L. Zaninetti
Dipartimento di Fisica Generale
Universita degli Studi di Torino, Italy
zaninetti@ph.unito.it
Received: 2009 May 7
Accepted: 2010 January 6
Abstract: The 3D network originated by the faces of irregular Poissonian
Voronoi Polyhedrons may represent the backbone on which the galaxies are
originated. As a consequence the spatial appearance of the catalogs of galaxies can
be reproduced. The selected catalogs to simulate are the 2dF Galaxy Redshift
Survey and the Third Reference Catalog of Bright Galaxies. In order to explain
the number of observed galaxies for a given flux/magnitude as a function of the
redshift, the photometric properties of the galaxies should be carefully examined
from both the astronomical and theoretical point of view. The statistics
of the Voronoi normalized volume is modeled by two distributions and
the Eridanus super-void is identified as the largest volume belonging to
the Voronoi Polyhedron. The behavior of the correlation function for
galaxies is simulated by adopting the framework of thick faces of Voronoi
Polyhedrons on short scales, while adopting standard arguments on large
scales.
December 2009
Age Estimation And Mass Functions of TTauri Stars
in Taurus Auriga Molecular Cloud
. Küçük and
. Akkaya
Department of Astronomy and Space Sciences
Erciyes University, Turkey
kucuk@erciyes.edu.tr
Received: 2009 July 10
Accepted: 2009 December 14
Abstract: In this work the Present Day Mass Functions (PDMF) of T-Tauri
Stars (TTS) which are in the Pre-Main Sequence (PMS) evolutionary phase of
their evolution in Taurus-Auriga Molecular Cloud Complex have been calculated.
For this purpose, by applying our modified Stellar Evolutionary Code, stellar
models in the mass range 0.1 - 2
.5 M
are used to determine the mass and age
mass of TTS. The obtained mass function is compared with mass function of Miller & Scalo (1979).
The age found for TTS is around 1 - 3
× 106 yr and mass
function is about 0.644
0.348. From these results, we
have calculated the stellar birthrate as about 1.3
× 10-
7 M
yr
-1 in this region, that is to be
considered.
November 2009
The green potential of the San Pedro Mártir observatory
J. Bohigas and J. M. Núñez
Instituto de Astronomía
Universidad Nacional Autónoma de México, Ensenada, Mexico
jbb@astrosen.unam.mx
Received: 2009 September 17
Accepted: 2009 November 23
Abstract: Weather observations carried out between October 2004 and July
2008 at the Mexican Observatorio Astronómico Nacional (OAN) are analyzed.
Humidity in April, May and June was less than 55% nearly 90% of the time.
Wind speed was larger at nightime and tended to decrease between March and
November, and typical temperature variations during the night, for the entire day
and for a whole year were about 2, 6 and 16oC respectively. The scale height or
roughness length for the function relating wind speed and height above
ground is 0.32. Normal activities associated to OAN produced somewhat
more than 750 tones of CO2eq a year, roughly 3 times more than a typical
mid-scale industry in the district of Ensenada, where OAN is located.
Wind energy could have been extracted to produce electricity ~ 60% of
the time, being more bountiful during the night and in the winter and
early spring months. Solar and wind energy seem plentiful enough to
supply the entire energy needs of the observatory, some 110 kWh including
transportation.
Photoevaporation of a binary proplyd system
M. J. Vasconcelos,1 A. H. Cerqueira,1 A. C. Raga,2 and R. R. Amorim3
1LATO-DCET, Universidade Estadual de Santa Cruz, Ilhéus Bahia, Brazil
2Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de
México, Mexico
3Instituto Nacional de Pesquisas Espaciais, São José dos Campos, São
Paulo, Brazil
mjvasc@uesc.br
Received: 2009 September 21
Accepted: 2009 November 17
Abstract: We present 3D numerical simulations of photo-evaporation of a
binary accretion disk system inside an H II region. The simulations take into
account far- and extreme-ultraviolet (FUV and EUV) radiation from a stellar
source. We study both FUV dominated and EUV dominated models. FUV
dominated models show a well defined interproplyd shell in both H
emission and
density maps, when the separation of the binary system is relatively large
(~ 2 000 AU). For smaller separations (
200 AU), the interproplyd shell no
longer develops. We show that an EUV model with a suitable choice of
parameters increases the H
emission of the interproplyd shell relative to the
emission of the ionization fronts, in better agreement with the observations of the
binary proplyd LV1.
Herbig-Haro objects around CG 30
P. Kajdi
,1,2 B. Reipurth,3 A. C. Raga,4 and J. Walawender3
1Instituto de Geofísica, Universidad Nacional Autónoma de México, Mexico
2Instituto de Astronomía, Universidad Nacional Autónoma de México,
Mexico
3Institute for Astronomy, University of Hawaii, USA
4Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de
México, Mexico
primoz@geofisica.unam.mx
Received: 2009 August 6
Accepted: 2009 November 5
Abstract: In this work we study Herbig-Haro objects located in the region
around the head of the cometary globule CG 30. Two sets of optical images are
presented. The first set was obtained with the 3.5 m New Technology Telescope
in 1995 in three emission lines: H
, [SII]
6731,6716 Å and [OII]
3729 Å. The
second set is an H
image of the CG 30/31/38 complex obtained in 2006 with the
8 m Subaru telescope. A proper motion study of the HH objects in the region was
performed using the H
images from both epochs. Due to the high resolution of
our images we were able to, for the first time, resolve the HH 120 object into
ten knots and measure proper motions for some of them. We discovered
several new HH objects which are best seen in our [SII] image as well as a
large bipolar jet, HH 950, emerging from the head of CG 30. We suggest
that two previously known submillimeter sources are the driving sources
for the HH 120 and HH 950 flows. They could both be binary sources,
because (1) the proper motion vectors of the HH 120 knots suggest that this
object is actually composed of two outflows and (2) the structure of the
HH 950 flow suggests that the direction of the jet axis has changed in the
past.
On the Precursors of Fossil Groups
Hrant Tovmassian
Instituto Nacional de Astrofísica, Óptica y Electrónica, Puebla, Mexico
hrant@inaoep.mx
Received: 2009 August 25
Accepted: 2009 November 4
Abstract: We compare the absolute magnitudes in K-band of the brightest
galaxies in clusters of Bautz-Morgan type I with that of the fossil group
brightest galaxies. It is found that brightest galaxies in fossil groups are on
average fainter than the brightest galaxies in clusters. It is also shown that
the brightness of the brightest galaxy depends on the cluster richness. It
is concluded that the precursors of fossil groups were on average poor
clusters.
October 2009
A Photometric and Spectroscopic Evaluation of the Site at
Tonantzintla Observatory
H. M. Hernández-Toledo,1 L. A. Martínez-Vázquez,1 M. A. Moreno-Corral,2
and A. Pani-Cielo,3
1Instituto de Astronomía, Universidad Nacional Autónoma de México, D.
F., Mexico
2Instituto de Astronomía, Universidad Nacional Autónoma de México,
Ensenada, B. C., Mexico
3Instituto de Astronomía, Universidad Nacional Autónoma de México,
Tonantzintla, Puebla, Mexico
(hector@astroscu.unam.mx
Received: 2009 March 24
Accepted: 2009 October 15
Abstract: Based on data obtained during various observing campaigns at the
Observatorio Astronómico Nacional, Tonantzintla, an evaluation of the quality of
the local sky is presented, and at the same time, the operability of the current
photometric and spectroscopic instrumentation attached to the 1-m telescope
is reviewed. The evaluation was carried out through an absolute CCD
calibration to a set of standard stars in the field of the M67 star cluster
in the B, V , R and I Johnson-Cousins photometric system and from
Boller & Chivens long-slit spectroscopic observations of the local sky at
various elevations. The sky brightness was estimated from our CCD frames
and from a first visual campaign implemented in a local area of ~ 8km2
around the observatory yielding a mean sky surface brightness of 18.5
± 0.6 mag arcsec-2. The mean atmospheric extinction curve was also
estimated, its behavior lying between the normal extinction and that
related to volcanic outbursts. Compelling evidence relating that behavior to
the activity of the nearby Popocatépetl volcano is presented. From the
long-slit spectra of the sky at OAN-Tonantzintla, HgI Mercury lamp
lines and NaI Sodium lines either of high and low pressure (HPS and
LPS) lamps were identified. Comments on plausible astronomical projects
under reasonable weather conditions and observing strategies as well as
useful recommendations to improve on the current observing efficiency are
provided. These results are relevant to providing support for the actual major
upgrading of the observatory in terms of converting the OAN-Tonantzintla in
the Laboratory for Astronomy Education at UNAM and eventually in a
National Facility for Astronomy Education for the center-south part of the
country.
September 2009
IMF from infrared photometry of young stellar clusters in
Taurus-Auriga and Orion
Luis Salas and Irene Cruz-González
Instituto de Astronomía, Universidad Nacional Autónoma de México, Mexico
salas@astrosen.unam.mx
Received: 2009 June 8
Accepted: 2009 September 28
Abstract: We applied the extinction-disk-principal vectors approach to near
infrared photometric data of the Taurus-Auriga region and Orion Nebula young
stellar clusters. By assuming that the cluster age is represented by the median
value of the age distribution we are able to derive the distribution of stellar
masses. We showed that the resulting initial mass function (IMF) for these two
young stellar clusters compares remarkably well and might be a robust
representation of the IMF obtained by spectroscopic or photometric methods. The
method also yields extinction and disk contribution for each star. The overall
extinction distribution for the Orion cluster is analyzed and compares
well with previous work. The frequency of T Tauri stars with disks is
dominant.
H91
Radio Recombination Line and 3.5 cm Continuum
Observations of the Planetary Nebula NGC 3242
L. F. Rodríguez,1 Y. Gómez,1 J. Alberto López,2 Ma. Teresa
García-Díaz,2 and David M. Clark2
1Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma
de México, Morelia, Mexico
2Instituto de Astronomía, Universidad Nacional Autónoma de México,
Ensenada, Mexico
l.rodriguez@crya.unam.mx
Received: 2009 August 25
Accepted: 2009 September 25
Abstract: We present high sensitivity H91
and 3.5 cm radio continuum
observations toward the planetary nebula NGC 3242. The electron temperature
determined assuming local thermodynamic equilibrium is consistent within ~10%
with that derived from optical lines and the Balmer discontinuity. The line
emission and the continuum emission have very similar spatial distribution,
suggesting that at this wavelength there is no other continuum process present in
a significant manner. In particular, we conclude that emission from spinning dust
is not important at this wavelength. In this radio recombination line the nebula
presents a radial velocity structure consistent with that obtained from
observations of optical lines.
CCD Photometry of M15
A. Ruelas-Mayorga,1 L. J. Sánchez,1 G. Herrera,2 and A. Nigoche-Netro3
1Instituto de Astronomía, Universidad Nacional Autónoma de México,
Mexico
2Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de
México, Mexico
3Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain
rarm@astroscu.unam.mx
Received: 2009 January 9
Accepted: 2009 September 14
Abstract: We present CCD observations of the galactic globular cluster M15,
in the B and V filters. The cluster was reasonably covered, except in its
northern region where our observations present a gap. We obtained a
Hertszprung-Russell (HR) diagram for each region observed, and later
we produced a combined HR diagram containing more than 3000 stars.
We generate a clean Colour Magnitude Diagram (CMD) and a Super
Fiducial Line (SFL). Application of several methods and isochrone fitting
leads us to obtain values for the metallicity [Fe/H]M15 ~-2.16 ± 0.10,
the reddening E(B - V )M15 ~ 0.11 ± 0.03, and a distance modulus of
[(m - M)0]M15 ~ 15.03.
SIMPLE MODEL WITH TIME-VARYING
FINE-STRUCTURE ”CONSTANT” - PART II
M. S. Berman
Instituto Albert Einstein, Curitiba, PR, Brazil
msberman@institutoalberteinstein.org
Received: 2009 June 22
Accepted: 2009 September 1
Abstract: The extension of Dirac’s LNH to cover cosmological and
fine-structure time-varying “constants”, and the rotation of the Universe, is here
analysed, including a “derivation” of the angular speed of the present Universe,
and of the inflationary phase. Criticizable points on the present calculation, are
clarified.