Papers by Raul Michel Murillo
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
An investigation of the O-C times has been carried out, using a data set based on the previous pu... more An investigation of the O-C times has been carried out, using a data set based on the previous published times of light maxima, largely enriched by those obtained during an intensive multisite photometric campaign of BL Cam lasting several months. (1 data file).
Ground-based and Airborne Instrumentation for Astronomy II, 2008
This work presents the specifications, requirements, design, finite element analysis and results ... more This work presents the specifications, requirements, design, finite element analysis and results of the assembled subsystems: slit-mask, and the acquisition and guiding zone mechanisms of the ESOPO spectrograph. This spectrograph is a project of the Institute of Astronomy, National University of Mexico.
SPIE Proceedings, 2008
The structure of the spectrograph ESOPO is the stiff mount that will maintain fixed all optics el... more The structure of the spectrograph ESOPO is the stiff mount that will maintain fixed all optics elements, electronics and mechanical subsystems. The ESOPO spectrograph is a project of the "Instituto de Astronomia de la Universidad Nacional Autonoma de Mexico" (IAUNAM) to upgrade its 2.1m telescope as a competitive facility for the next decade. The scientific purpose is to obtain a
RevMexAA (Serie …, 2007
El análisis se basa en datos obtenidos para la caracterización del lugar desde el punto de vista ... more El análisis se basa en datos obtenidos para la caracterización del lugar desde el punto de vista astronómico, así como en datos de lluvia, humedad, temperatura, viento y otros obtenidos en distintas estaciones climatológicas operadas por la Comisión Nacional del Agua y otras dependencias. Se usan algunos índices derivados de la temperatura superficial del mar (TSM) y de los anillos de crecimiento de corteza en los árboles para estudiar la variación climática del pasado y para predecir un escenario futuro de la precipitación pluvial en Ensenada. Se mencionan las posibles implicaciones que podría tener el Cambio Climático Global en la región del Norte de Baja California.
arXiv (Cornell University), May 25, 2010
Preliminary results on the discovery and follow-up observations of a new δ Scuti pulsator in the ... more Preliminary results on the discovery and follow-up observations of a new δ Scuti pulsator in the Cygnus field are presented. The variability of the star HD 207331 was detected while testing a Strömgren spectrophotometer attached to the H. L. Johnson 1.5-m telescope at the San Pedro Mártir observatory, México. CCD photometric data acquired soon after confirmed its variability. A few hours of uvby differential photoelectric photometry during three nights revealed at least two beating periods. A two-site observational campaign carried out during one week in 2009 confirms the multi-periodic nature of this new δ Scuti pulsator.
Revista Mexicana De Astronomia Y Astrofisica, 2010
The fundamental parameters of reddening, metallicity, age, and distance are presented for the poo... more The fundamental parameters of reddening, metallicity, age, and distance are presented for the poorly studied open clusters Be 89, Ru 135, and Be 10, derived from their CCD UBVRI photometry. The interstellar reddenings, E(B–V ), were measured in the two-color diagram, and the photometric metallicities, [Fe/H], from the ultraviolet excesses of the F-type stars. By fitting isochrones to the observed sequences of the clusters in five different color-magnitude diagrams, the weighted averages of distance moduli and heliocentric distances [(V0–MV ), d(kpc)] are (11.m 90 ± 0.m 06, 2.4 ± 0.06) for Be 89, (9.m 58 ± 0.m 07, 0.81 ± 0.03) for Ru 135, and (11.m 16 ± 0.m 06, 1.7 ± 0.05) for Be 10, and the weighted averages of the ages [log(A),A(Gyr)] are (9.58 ± 0.06, 3.8 ± 0.6) for Be 89, (9.58 ± 0.06, 3.8 ± 0.7) for Ru 135, and (9.06 ± 0.05, 1.08 ± 0.08) for Be 10.
Research in Astronomy and Astrophysics, 2020
We present the results of our study of the eclipsing binary systems CSS J112237.1+395219, LINEAR ... more We present the results of our study of the eclipsing binary systems CSS J112237.1+395219, LINEAR 1286561 and LINEAR 2602707 based on new CCD B, V, Rc and Ic complete light curves. The ultra-short period nature of these stars, as reported by Drake et al., is confirmed and the system’s periods are revised. The light curves were modeled using the 2003 version of the Wilson-Devinney code. When necessary, cool spots on the surface of the primary component were introduced to account for asymmetries in the light curves. As a result, we found that CSS J112237.1+395219 is a W UMa type contact binary system belonging to W subclass with a mass ratio of q = 1.61 and a shallow degree of contact of 14.8% where the primary component is hotter than the secondary one by 500 K. LINEAR 1286561 and LINEAR 2602707 are detached binary systems with mass ratios q = 3.467 and q = 0.987 respectively. These detached systems are low-mass M-type eclipsing binaries with similar temperatures. The marginal contact...
Publications of the Astronomical Society of Japan, 2018
There are several peculiar long-period dwarf-nova-like objects that show rare, lowamplitude outbu... more There are several peculiar long-period dwarf-nova-like objects that show rare, lowamplitude outbursts with highly ionized emission lines; 1SWASP J162117+441254, BD Pav, and V364 Lib are among them. Some researchers even doubt whether 1SWASP J1621 and V364 Lib have the same nature as normal dwarf novae. We studied the peculiar outbursts in these three objects via our optical photometry and spectroscopy, and performed numerical modeling of their orbital variations to investigate their properties. We found that their outbursts lasted for a long interval (a few tens of days), and that slow rises in brightness were commonly observed during the early stage of their outbursts. Our analyses and numerical modeling suggest that 1SWASP J1621 has a very high inclination, close to 90 • , plus a faint hot spot. Although BD Pav seems to have a slightly lower inclination (∼75 •), the other properties are similar to those in 1SWASP J1621. On the other hand, V364 Lib appears to have a massive white dwarf, a hot companion star, and a low inclination (∼35 •). In addition, these three objects possibly have a low transfer rate and/or large disks originating from the long orbital periods. We found that these properties of the three objects can explain their infrequent and low-amplitude outbursts within the context of the disk instability model in normal dwarf novae without a strong magnetic field. In addition, we suggest that the highly ionized emission lines in outburst are observed due to a high inclination and/or a massive white dwarf. More instances of this class of object may be unrecognized, since their unremarkable outbursts can be easily overlooked.
International Astronomical Union Colloquium, 2004
Photon counting detector technology allows high time resolution spectroscopy on sources such as p... more Photon counting detector technology allows high time resolution spectroscopy on sources such as pulsars and cataclysmic variables. Here we report on first observing trials on Cvs in a high time resolution mode undertaken with the MIC photon counting detector (Fordham et al. 2000) on the 2.1m telescope at San Pedro Martir Observatory.
The Astronomical Journal, 2018
New multi-band CCD light curves of three binaries W UMa-type V1175 Her, NSVS 2669503, and 1SWASP ... more New multi-band CCD light curves of three binaries W UMa-type V1175 Her, NSVS 2669503, and 1SWASP J133417.80+394314.4 are presented. Spectroscopic data for V1175 Her and NSVS 2669503 show that their spectral types are G7V and K4V, respectively. Photometric solutions of these three objects were obtained with the help of the Wilson-Devinney program. We find that V1175 Her is a semi-detached binary star with a hot spot located on the secondary component, while NSVS 2669503 and 1SWASP J133417.80+394314.4 are contact eclipsing binaries with contact factors of f=1.070±0.002% and f=21.250±0.005%, respectively. Moreover, we found that the orbital period of V1175 Her is increasing at a rate of (+3.1±0.1)×10 −7 days yr −1. This increase may be attributed to a dM dt M 0.93 10 yr 1 7 1 =-´- mass-transfer rate from the primary to the secondary component. Finally, we discuss the evolutionary stage of the component stars of these three systems.
The Astrophysical Journal, 2017
1SWASP J162117.36+441254.2 was originally classified as an EW-type binary with a period of 0.2078... more 1SWASP J162117.36+441254.2 was originally classified as an EW-type binary with a period of 0.20785 days. However, it was detected to have undergone a stellar outburst on 2016 June 3. Although the system was later classified as a cataclysmic variable (CV) and the event was attributed as a dwarf nova outburst, the physical reason is still unknown. This binary has been monitored photometrically since 2016 April 19, and many light curves were obtained before, during, and after the outburst. Those light and color curves observed before the outburst indicate that the system is a special CV. The white dwarf is not accreting material from the secondary and there are no accretion disks surrounding the white dwarf. By comparing the light curves obtained from 2016 April 19 to those from September 14, it was found that magnetic activity of the secondary is associated with the outburst. We show strong evidence that the L 1 region on the secondary was heavily spotted before and after the outburst and thus quench the mass transfer, while the outburst is produced by a sudden mass accretion of the white dwarf. These results suggest that J162117 is a good astrophysical laboratory to study stellar magnetic activity and its influences on CV mass transfer and mass accretion.
Monthly Notices of the Royal Astronomical Society, 2017
Observations for the δ Scuti star AN Lyn have been made between 2008 and 2016 with the 85cm teles... more Observations for the δ Scuti star AN Lyn have been made between 2008 and 2016 with the 85cm telescope at Xinglong station of National Astronomical Observatories of China, the 84-cm telescope at SPM Observatory of Mexico and the Nanshan One metre Wide field Telescope of Xinjiang Observatory of China. Data in V in 50 nights and in R in 34 nights are obtained in total. The bi-site observations from both Xinglong Station and SPM Observatory in 2014 are analysed with Fourier Decomposition to detect pulsation frequencies. Two independent frequencies are resolved, including one non-radial mode. A number of stellar model tracks are constructed with the MESA code and the fit of frequencies leads to the best-fitting model with the stellar mass of M = 1.70 ± 0.05 M , the metallicity abundance of Z = 0.020 ± 0.001, the age of 1.33 ± 0.01 billion years and the period change rate 1/P • dP/dt = 1.06 × 10 −9 yr −1 , locating the star at the evolutionary stage close to the terminal age main sequence. The O−C diagram provides the period change rate of (1/P)(dP/dt) = 4.5(8) × 10 −7 yr −1. However, the period change rate calculated from the models is smaller in two orders than the one derived from the O−C diagram. Together with the sinusoidal function signature, the period variations are regarded to be dominated by the light-travel time effect of the orbital motion of a three-body system with two low-luminosity components, rather than the stellar evolutionary effect.
AIP Conference Proceedings, 2009
The preliminary results of a three-site CCD photometric campaign are reported. The δ Scuti variab... more The preliminary results of a three-site CCD photometric campaign are reported. The δ Scuti variable V650 Tauri belonging to the Pleiades cluster was observed photometrically for 14 days on three continents during 2008 November. An overall run of 164 hr of data was collected. At least five significant frequencies for V650 Tauri have been detected.
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Papers by Raul Michel Murillo