Papers by Raul Michel Murillo
AIP Conference Proceedings, 2002
We have observed WZ Sge with high resolution echelle spectroscopy during the 2001 superoutburst. ... more We have observed WZ Sge with high resolution echelle spectroscopy during the 2001 superoutburst. The hot-spot arising near the secondary star is again visible 15 days after its first detection. We have been able to measure its position as a function of orbital phase directly from individual spectra. We derive a a semiamplitude of Khs = 457 +/- 16km s-1
We report spectroscopic observations of the low-inclination dwarf nova EY Cyg, spanning eleven ye... more We report spectroscopic observations of the low-inclination dwarf nova EY Cyg, spanning eleven years. The radial velocity curves for both the emission and absorption components are determined for the first time. The orbital period is found to be 0.45932448(9) days, a value much larger than previously reported. The system inclination and, hence, the mass of each stellar component are estimated within very tight limits. In particular, we conclude that the mass of the white dwarf must be near the Chandrasekhar limit. We also performed photometric observations, some of them simultaneous to the spectroscopic runs. The light curve shows oscillations with a period of 0.494027 days. Its deference with the orbital period is statistically significant and similar to the so-called "permanent superhumps" observed in shorter period dwarf novae. The significance of this phenomenon is analyzed.
A sample of 26 dwarf novae was observed in the Stroemgren photometric system. The observations we... more A sample of 26 dwarf novae was observed in the Stroemgren photometric system. The observations were performed on 3 different seasons in 1986 January, February and July, with a 6-channel photometer attached to the 1.5m telescope if the Observatorio Astronomicao Nacional at San Pedro Martir, Baja California, Mexico. A number of standard stars were observed, and a nearby comparison star
The Astrophysical Journal, 2002
ABSTRACT High time resolution spectroscopic imaging of the Crab pulsar across the optical wave ba... more ABSTRACT High time resolution spectroscopic imaging of the Crab pulsar across the optical wave band has been undertaken utilizing the 4 m Mayall telescope at Kitt Peak National Observatory. The 33.51 ms period of the pulsar was split into 723.7 time slices of 46.3 μs and a spectrum within each slice acquired. These data have allowed analysis of both the light curve as a function of wavelength and the spectrum as a function of phase position. Wavelength-dependent changes in phase position for both emission peaks have been found, and these appear to be uncorrelated. Related to these changes are phase position-dependent variations in the spectral index, and these have been measured, the shapes being in agreement with previously published data. Also related are energy-dependent changes in the FWHMs. In addition, we find, in support of previously published data, that the fluence of Peak 2 relative to Peak 1 decreases with increasing wavelength. These results then challenge the validity of currently existing models for pulsar emission.
We conducted a series of photometric and spectroscopic observations of FS Aur during quiescence. ... more We conducted a series of photometric and spectroscopic observations of FS Aur during quiescence. We spectroscopically confirmed its short Porb ≅ 87m. But long-term photometry revealed a distinct 0fm24 modulation in the BV R bands with a period of ~205 min, which is 2.4 times longer than Porb. We discuss possible causes for this peculiar behaviour.
RevMexAA (Serie de …, 2003
Se encuentra una distribución log-normal con valor mediano de 27.0 m. La importancia de L 0 en la... more Se encuentra una distribución log-normal con valor mediano de 27.0 m. La importancia de L 0 en la derivación del desempeño de la óptica adaptativa (OA) es analizada. Se demuestra que valores bajos de L 0 incrementan las habilidades correctoras de la OA de bajo orden, pero no tienen prácticamente ningún efecto en OA de alto orden.
… de Astronomia y …, 2003
Hemos llevado a cabo una nueva campaña para medir el seeing en el sitio del Observatorio Astronóm... more Hemos llevado a cabo una nueva campaña para medir el seeing en el sitio del Observatorio Astronómico Nacional en San Pedro Mártir, esta vez empleando un DIMM. Los resultados obtenidos durante 123 noches, distribuidas en un lapso de casi tres años, arrojan una mediana de 0.60 segundos de arco con un primer cuartil de 0.48 segundos de arco. Estos valores se midieron a 8.3 m del suelo y con un tiempo de exposición de 6 ms. Mostramos que el seeing puede ser excelente y muy estable durante noches enteras; las mejores medidas dan una mediana de 0.37 segundos de arco, y un primer cuartil de 0.32 segundos de arco, en observaciones obtenidas durante más de ocho horas continuas. Los presentes resultados concuerdan muy bien con nuestro estudio previo del sitio. El valor esperado de la mediana del seeing a una altura de 15 m y extrapolando a tiempo nulo de exposición es de 0.61 segundos de arco. Por último, comparamos San Pedro Mártir con los principales sitios del mundo donde se ha medido el seeing con instrumentos DIMM. De esta comparación concluimos que San Pedro Mártir es uno de los mejores sitios astronómicos en el mundo.
… de Astronomía y …, 1998
Revista Mexicarza de AstronornIa y AstrofIsica, 34, 4760 (1998) SITE TESTING AT OBSERVATORIO AST... more Revista Mexicarza de AstronornIa y AstrofIsica, 34, 4760 (1998) SITE TESTING AT OBSERVATORIO ASTRONOMICO NACIONAL IN SAN PEDRO MARTIR J. EchevarrIa, M. Tapia, R. Costero, L. Salas, Rm. Michel, Ri. Michel MA Rojas, R. Muñoz, J. Valdez, JL Ochoa, J. Palomares, ...
RevMexAA (Serie de …, 2002
Se presentan observaciones espectroscópicas echelle de V751 Cygni y su región circundante. Aunque... more Se presentan observaciones espectroscópicas echelle de V751 Cygni y su región circundante. Aunque las observaciones de rendija larga muestran la presencia de emisión variable en dicho material, las temperaturas y densidades derivadas de las líneas de [O II], [O III] y [S II] sugieren que el material viene del fondo y no está conectado con la variable cataclísmica. Un análisis de la curva de velocidad radial de la línea de Hα arroja un periodo orbital de 0.144584 días.
Astronomy and Astrophysics, 2002
The first measurements of the spatial coherence outer scale at the Observatorio Astronómico Nacio... more The first measurements of the spatial coherence outer scale at the Observatorio Astronómico Nacional at San Pedro Mártir (OAN-SPM) are reported along with long term seeing measurements. These parameters were measured with the Generalized Seeing Monitor and with a Differential Image Motion Monitor. An instrumented mast was also used to measure the structure constant of the refractive index C 2 n in the first 15 m. Log-normal statistics were found for the seeing and for the outer scale, with median values of 0.92 and 27.0 m, respectively. The distribution of the outer scale values is similar to that found in other observatories around the world, suggesting that the presence of trees in the OAN-SPM do not affect the outer scale values. Correlation studies suggest that large values of the seeing and the outer scale are likely to occur when the wind blows from the SSW. Further studies are recommended to confirm this tendency.
New Astronomy, 2018
Photometric observations in V, R c and I c bands of the ultrashort-period W UMa binaries 1SWASP J... more Photometric observations in V, R c and I c bands of the ultrashort-period W UMa binaries 1SWASP J044132.96+440613.7, 1SWASP J052926.88+461147.5 and NSVS 2175434 are presented. The results from the modeling and analysis of our observations reveal that: (i) All targets undergo total eclipses and their photometric mass ratios should be accepted with confidence; (ii) All stellar components are late-type dwarfs; (iii) The temperature difference of target components does not exceed 150 K; (iv) All targets have overcontact configurations with fill-out factor around 0.24; (v) The orbit of NSVS 2175434 is slightly eccentric which is unusual for such an ultrashort-period binary; (vi) The orbital periods of all targets were improved. Masses, radii and luminosities of the stellar components were estimated by the empirical relation "period, orbital axis" for short-and ultrashort-period binaries.
Computers and Electronics in Agriculture, 2017
Abstract We describe the design and implementation of a low-cost electronic modular data-acquisit... more Abstract We describe the design and implementation of a low-cost electronic modular data-acquisition (DAQ) system in the context of the eddy-covariance technique. The system was fully tested under laboratory conditions and later installed on two eddy-covariance towers (ECTs) sited in natural terrestrial and marine environments, respectively. The system was divided in four parts: signal conditioning, data-acquisition, data-transfer and data-processing. A data-acquisition module (DAM) based on the ADuC848 microcontroller was designed in order to acquire these data. This DAM could transfer data directly to a computer or embedded system. By configuring a RS-485 network, a DAQ system could be expanded up to 8 DAMs working simultaneously. Due to its modular design, different parts of the equipment could be easily replaced without affecting the operation of the ECT. The system registered high-frequency (20 Hz) measurements of CO 2 , water vapor and wind velocity in the free atmosphere as well as additional ancillary biometeorological variables (1/60 Hz) such as air temperature, solar radiation, soil heat flux, precipitation, and others. Both towers were installed in remote sites using solar cells providing a continuous and autonomous source of energy. This DAQ system proved to be reliable and useful for long-term deployments (> 1 year). Due to its modularity and flexibility the system can be used for any other application involving data recording.
ABSTRACT KUV 08368+4026 was considered a member of ZZ Ceti stars with large amplitudes and freque... more ABSTRACT KUV 08368+4026 was considered a member of ZZ Ceti stars with large amplitudes and frequencies around a narrow range of 1.6 mHz and 2.0 mHz. As the first effort of asteroseismological study for KUV 08368+4026 since the discovery of its variability in 1996, a single‐site run in February of 2009 and a 3‐site observation campaign from December of 2009 to January of 2010 for KUV 08368+4026 were carried out in China and Mexico. More than 15,000 frames on 32 nights were obtained. 19 frequencies were distinguished in the datasets with 8 frequencies identified as independent modes. These results are helpful in determining stellar parameters including mass, rotation period, hydrogen mass fraction, and in constructing practical stellar and oscillation models, which will bring new knowledge about the internal structures of ZZ Ceti stars.
We observed a new cataclysmic variable (CV) SDSS J080434.20+510349.2 to study the origin of long-... more We observed a new cataclysmic variable (CV) SDSS J080434.20+510349.2 to study the origin of long-term variability found in its light curve. Multi-longitude, time-resolved, photometric observations were acquired to analyze this uncommon behavior, which has been found in two newly discovered CVs. This study of SDSS J080434.20+510349.2 concerns primarily the understanding of the nature of the observed, double-humped, light curve and
IAUNAM is building an optical, high efficiency, intermediate-low dispersion spectrograph (R ˜ 500... more IAUNAM is building an optical, high efficiency, intermediate-low dispersion spectrograph (R ˜ 5000 - 500) for general astronomical purposes, for use at the cassegrain f /7.5 focus of the 2.1-m telescope after-guider. The instrument should cover simultaneously a spectral range of 3500 - 9000 Å, with a long slit with spatial field of view no less than 8 arc minutes.
Ground-based and Airborne Instrumentation for Astronomy II, 2008
In this paper we present the Medium Resolution Spectrograph ESOPO, an instrument designed and bui... more In this paper we present the Medium Resolution Spectrograph ESOPO, an instrument designed and built for the 2.1m Telescope at the Observatorio Astronómico Nacional at San Pedro Mártir. We discuss the Scientific Goals and the High Level Requirements necessary to translate these goals to optical, mechanical and control specifications. We make an introduction to its conceptual dual-arm design. The optical
Ground-based and Airborne Instrumentation for Astronomy II, 2008
ESOPO will be a spectrograph of medium resolution for the 2.1 m telescope of the National Observa... more ESOPO will be a spectrograph of medium resolution for the 2.1 m telescope of the National Observatory at San Pedro Martir, Baja California, Mexico. It has been developed by the Instituto de Astronomia of the Universidad Nacional Autonoma de Mexico (IA-UNAM). The main goal of this instrument is to modernize the capabilities of making science with that particular telescope. It
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Papers by Raul Michel Murillo