Browsing by Author "Beamin Muhlenbrock, Juan Carlos"
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- ItemDiscovery of a brown dwarf companion to the A3V star beta Circini(2015) Smith, L.; Lucas, P.; Pena, C.; Kurtev, R.; Marocco, F.; Jones, H.; Beamin Muhlenbrock, Juan Carlos; Napiwotzki, R.; Borissova, J.; Burningham, B.; Faherty, J.; Pinfield, D.; Gromadzki, M.; Ivanov, V.; Minniti, D.; Stimson, W.; Villanueva, V.
- ItemPEERING THROUGH THE DUST: PRECISE ASTROMETRY IN THE GALACTIC MID-PLANE WITH THE VVV SURVEY(2015) Lucas, PW; Smart, RL; Jones, HRA; Kurtev, R; Beamin Muhlenbrock, Juan Carlos; Borissova, J.; Gromadzki, Grzegorz; Ivanov, Valentin; Minniti, Dante; Pinfield, DJGaia will see little of the Galactic mid-plane and nuclear bulge due to high extinction at optical wavelengths. To study the structure and kinematics of the inner Galaxy we must look to longer wavelengths. The Vista Variables in the Via Lactea (VVV, Minniti et al. 2010) survey currently provides just over 4 years of observations covering approximately 560 square degrees of the Galactic bulge and plane. Typically each source is observed 50-150 times in the Ks band over this period. Using these data we provide relative proper motions for approximately 200 million unique sources down to Ks similar to 16 with uncertainties approaching 1 mas yr(-1). In addition, we fit a solution of the parallactic motion of all sources with significant proper motion and discover a number of new nearby brown dwarfs. These results will allow us to identify faint common proper motion companions to stars with Gaia parallaxes, increasing the number of brown dwarf benchmark objects. Our absolute astrometric calibration precision is currently similar to 2 mas yr(-1), based on PPMXL. The Gaia absolute astrometric reference grid will allow us to precisely anchor our results and measure the streaming motions of stars in the bulge. Finally, we anticipate that the catalogue could provide kinematic distances to the numerous optically invisible high amplitude variable stars that VVV is discovering.
- ItemQualitative classification of extraterrestrial civilizations(2020) Ivanov, Valentín D.; Beamin Muhlenbrock, Juan Carlos; Cáceres Acevedo, Claudio Cesar; Minniti, DanteAbridged: The interest towards searches for extraterrestrial civilizations (ETCs) was boosted by the discovery of thousands of exoplanets. We turn to the classification of ETCs for new considerations that may help to design better strategies for ETCs searches. We take a basic taxonomic approach to ETCs and investigate the implications of the new classification on ETCs observational patterns. We use as a counter-example to our qualitative classification the quantitative scheme of Kardashev. We propose a classification based on the abilities of ETCs to modify their environment and to integrate with it: Class 0 uses the environment as it is, Class 1 modifies the it to fit its needs, Class 2 modifies itself to fit the environment and Class 3 ETC is fully integrated with the environment. Combined with the classical Kardashev's scale our scheme forms a 2d scheme for interpreting ETC properties. The new framework makes it obvious that the available energy is not an unique measure of ETCs, it may not even correlate with how well that energy is used. The possibility for progress without increased energy consumption implies lower detectability, so the existence of a Kardashev Type III ETC in the Milky Way cannot be ruled out. This reasoning weakens the Fermi paradox, allowing the existence of advanced, yet not energy hungry, low detectability ETCs. The integration of ETCs with environment makes it impossible to tell apart technosignatures from natural phenomena. Thus, the most likely opportunity for SETI searches is to look for beacons, specifically set up by them for young civilizations like us (if they want to do that is a matter of speculation). The other SETI window is to search for ETCs at technological level close to ours. To rephrase the saying of A. Clarke, sufficiently advanced civilizations are indistinguishable from nature.
- ItemSearching for extragalactic sources in the VISTA variables in the VÍa láctea survey(2018) Baravalle, Laura D.; Victoria Alonso, M.; Castellón, José Luis Nilo; Beamin Muhlenbrock, Juan Carlos; Minniti, DanteWe search for extragalactic sources in the VISTA Variables in the Vía Láctea survey that are hidden by the Galaxy. Herein, we describe our photometric procedure to find and characterize extragalactic objects using a combination of SExtractor and PSFEx. It was applied in two tiles of the survey: d010 and d115, without previous extragalactic IR detections, in order to obtain photometric parameters of the detected sources. The adopted criteria to define extragalactic candidates include CLASS-STAR < 0.3; 1.0 < R1 2 < 5.0 arcsec; 2.1 < C < 5; and F > 0.002 and the colors: 0.5 < (J-Ks) < 2.0 mag; 0.0 < (J-H) < 1.0 mag; 0.0 < (H-Ks) < 2.0 mag and (J-H) + 0.9 (H-Ks) > 0.44 mag. We detected 345 and 185 extragalactic candidates in the d010 and d115 tiles, respectively. All of them were visually inspected and confirmed to be galaxies. In general, they are small and more circular objects, due to the near-IR sensitivity to select more compact objects with higher surface brightness. The procedure will be used to identify extragalactic objects in other tiles of the VVV disk, which will allow us to study the distribution of galaxies and filaments hidden by the Milky Way. © 2018. The American Astronomical Society. All rights reserved.
- ItemSub-millimeter non-contaminated detection of the disk around TWA\\,7 by ALMA(2019) Bayo, A.; Olofsson, Johan; Matra, L.; Beamin Muhlenbrock, Juan Carlos; Gallardo, J.; de Gregorio-Monsalvo, I.; Booth, M.; Zamora, C.; Iglesias, D.; Henning, Th.; R. Schreiber, M.; Cáceres Acevedo, Claudio CesarDebris disks can be seen as the left-overs of giant planet formation and the possible nurseries of rocky planets. While M-type stars out-number more massive stars we know very little about the time evolution of their circumstellar disks at ages older than $\sim 10$\,Myr. Sub-millimeter observations are best to provide first order estimates of the available mass reservoir and thus better constrain the evolution of such disks. Here, we present ALMA Cycle\,3 Band\,7 observations of the debris disk around the M2 star TWA\,7, which had been postulated to harbor two spatially separated dust belts, based on unresolved far-infrared and sub-millimeter data. We show that most of the emission at wavelengths longer than $\sim 300$\,$\mu$m is in fact arising from a contaminant source, most likely a sub-mm galaxy, located at about 6.6" East of TWA\,7 (in 2016). Fortunately, the high resolution of our ALMA data allows us to disentangle the contaminant emission from that of the disc and report a significant detection of the disk in the sub-millimeter for the first time with a flux density of 2.1$\pm$0.4 mJy at 870 $\mu$m. With this detection, we show that the SED can be reproduced with a single dust belt.
- ItemSub-millimetre non-contaminated detection of the disc around TWA 7 by ALMA(2019) Beamin Muhlenbrock, Juan Carlos; Bayo, A.; Olofsson, J.; Matrà, L.; Gallardo, J.; de Gregorio-Monsalvo, I.; Booth, M.; Zamora, C.; Iglesias, D.; Henning. Th; Schreiber, M.R.; Cáceres, C.Debris discs can be seen as the leftovers of giant planet formation and the possible nurseries of rocky planets. While M-type stars outnumber more massive stars we know very little about the time evolution of their circumstellar discs at ages older than ∼10 Myr. Sub-millimetre observations are best to provide first order estimates of the available mass reservoir and thus better constrain the evolution of such discs. Here, we present ALMA Cycle 3 Band 7 observations of the debris disc around the M2 star TWA 7, which had been postulated to harbour two spatially separated dust belts, based on unresolved far-infrared and sub-millimetre data. We show that most of the emission at wavelengths longer than ∼300 μm is in fact arising from a contaminant source, most likely a sub-mm galaxy, located at about 6.6 arcsec east of TWA 7 (in 2016). Fortunately, the high resolution of our ALMA data allows us to disentangle the contaminant emission from that of the disc and report a significant detection of the disc in the sub-millimetre for the first time with a flux density of 2.1 ± 0.4 mJy at 870 um. With this detection, we show that the spectral energy distribution can be reproduced with a single dust belt.
- ItemThe Gaia Ultracool Dwarf Sample. I. Known L and T dwarfs and the first Gaia data release(2017) Smart, R. L.; Marocco, F.; Caballero, J. A.; Jones, H. R. A.; Barrado, D.; Beamin Muhlenbrock, Juan Carlos; Pinfield, D. J.; Sarro, L. M.We identify and investigate known ultracool stars and brown dwarfs that are being observed or indirectly constrained by the Gaia mission. These objects will be the core of the Gaia ultracool dwarf sample composed of all dwarfs later than M7 that Gaia will provide direct or indirect information on. We match known L and T dwarfs to the Gaia first data release, the Two Micron All Sky Survey and the Wide-field Infrared Survey Explorer AllWISE survey and examine the Gaia and infrared colours, along with proper motions, to improve spectral typing, identify outliers and find mismatches. There are 321 L and T dwarfs observed directly in the Gaia first data release, of which 10 are later than L7. This represents 45 % of all the known LT dwarfs with estimated Gaia G magnitudes brighter than 20.3 mag. We determine proper motions for the 321 objects from Gaia and the Two Micron All Sky Survey positions. Combining the Gaia and infrared magnitudes provides useful diagnostic diagrams for the determination of L and T dwarf physical parameters. We then search the Tycho-Gaia astrometric solution Gaia first data release subset to find any objects with common proper motions to known L and T dwarfs and a high probability of being related. We find 15 new candidate common proper motion systems
- ItemVista variables in the via lactea (VVV): first results and perspectives(2011) Saito, R. K.; Minniti, D.; Dekany, I.; Hempel, M.; Alonso-Garcia, J.; Toledo, I.; Beamin Muhlenbrock, Juan Carlos; Angeloni, R.; Lucas, P. W.; Emerson, J. P.VISTA Variables in the Via Lactea (VVV) is a public ESO near-IR variability survey scanning the Milky Way Bulge and an adjacent section of the mid-plane. The survey will take 1929 hours of observations with the 4 m VISTA telescope during five years (2010-2014), covering similar to 10(9) point sources across an area of 520 deg(2). Here we address the first results obtained from the VVV Survey as well as a glimpse into the possibilities for using a deep near-IR atlas in five passbands and a catalogue of more than 10(6) variable point sources. We expect to use the data to find planetary transits of late-type main-sequence stars. We discuss the planet searches and future follow-ups
- ItemVVV High Proper Motion Survey(2013) Kurtev, R.; Beamin Muhlenbrock, Juan Carlos; Pena Ramirez, K.; Borissova, J.; Jones, H.; Minniti, D.Here we present survey of proper motion stars towards the Galactic Bulge and an adjacent plane region base on VISTA-VVV data. The searching method based on cross-matching photometric Ks-band CASU catalogs. The most interesting discoveries are shown.
- ItemVVV IR high proper motion stars(UNIVERSIDAD NACIONAL AUTONOMA MEXICO INSTITUTO ASTRONOMIA, 2015) Kurtev, R.; Gromadzki, M.; Beamin Muhlenbrock, Juan Carlos; Pena, K.; Folkes, S.; Ivanov, V. D.; Borissova, J.; Kuhn, M.; Villanueva, V.; Minniti, D.; Mendez, R.; Lucas, P.; Smith, L.; Pinfield, D.; Antonova, A.; Vieira, K; VanAltena, W; Mendez, RAWe used the VISTA Variables en Via Lactea (VVV) survey to search for large proper motion (PM) objects in the zone of avoidance in the Milky Way bulge and southern Galactic disk. This survey is multi-epoch and already spans a period of more than four years, giving us an excellent opportunity for proper motion and parallax studies. We found around 1700 PM objects with PM>30 mas yr(-1). The majority of them are early and mid M-dwarfs. There are also few later spectral type objects, as well as numerous new K- and G-dwarfs. 75 of the stars have PM>300 mas(-1) and 189 stars have PM>200 mas(-1). There are only 42 previously known stars in the VVV area with proper motion PM>200 mas(-1). We also found three dM+WD binaries and new members of the immediate solar vicinity of 25 pc. We generated a catalog which will be a complementary to the existing catalogs outside this zone.
- ItemVVVX near-IR photometry for 99 low-mass stars in the Gaia EDR3 Catalog of Nearby Stars(2022) Mejias, A.; Minniti, D.; Alonso-Garcia, J.; Beamin Muhlenbrock, Juan Carlos; Saito, R. K.; Solano, E.Context. Red dwarf stars, which represent 75% of stars in the Milky Way, can be studied in great detail in the solar neighborhood, where the sample is more complete.Aims. We intend to better characterize red-dwarf candidates selected from the Gaia Catalog of Nearby Stars using optical and near-infrared multi-filter photometry from the Vista Variables in the Via Lactea eXtended (VVVX) Survey, the DECam Plane Survey, the Panoramic Survey Telescope and Rapid Response System, and the Wide-field Infrared Survey Explorer.Methods. We performed a cross-matching procedure among the positions of a color-selected sample of M dwarfs in the VVVX Survey and the Gaia Early Data Release 3 sub-catalog of nearby stars. We explored their stellar parameters and spectral types using the Virtual Observatory SED Analyzer (VOSA). Radii were also obtained from the computed luminosities and T-eff using the Stefan-Boltzmann equation. Masses and ages were computed for some of the objects using evolutionary tracks and isochrones. Additional mass estimations were obtained with the M-Ks - M-* relation. We then validated our results for the stellar parameters of two of our objects with spectra obtained with the TripleSpec instrument at the SOAR telescope, as well as those of our total amount of stars through a direct comparison with an independent sample from the literature. We revised the objects in our sample and compared their proper motion vectors with other sources within 30 '' to identify possible companions and probed their renormalized unit weight error (RUWE) values to identify unresolved companions.Results. We present a catalog of physical parameters for 99 low-mass objects with distances from 43.2 to 111.3 pc. Effective temperatures range from 2500 to 3400 K, with the majority of stars in the sample compatible with the status of M4 dwarfs. We obtained a good agreement between the stellar parameters computed with VOSA and the estimations from observed spectra, also when comparing with an independent sample from the literature. The distribution of masses obtained with VOSA is concentrated toward the very low-mass regime. Eight objects present values of RUWE >= 1.4 and seven are consistent with being part of a binary system.
- ItemWeather on other worlds: BD variability and the VVV(UNIVERSIDAD NACIONAL AUTONOMA MEXICO INSTITUTO ASTRONOMIA, 2014) Kurtev, R.; Metchev, S.; Heinze, A.; Gromadzki, M.; Ivanov, V. D.; Minniti, D.; Beamin Muhlenbrock, Juan Carlos; Borissova, J.; Mateus, A; GregorioHetem, J; Fernandes, RCVarious evidences point to the presence of clouds in ultra-cool atmospheres. An important ambiguity remains as to whether all variability in ultra-cool dwarfs is caused by patchy clouds, or other fenomena like magnetic activity and auroras. Simultaneous multi-wavelength photometric and/or spectroscopic monitoring could help to reveal this enigma.
- ItemWeather on other worlds: BD variability and the VVV(Wiley, 2014) Kurtev, R.; Metchev, S.; Heinze, A.; Gromadzki, M.; Ivanov, V. D.; Minniti, D.; Beamin Muhlenbrock, Juan Carlos; Borissova, J.; Mateus, A; GregorioHetem, J; Fernandes, RCVarious evidences point to the presence of clouds in ultra-cool atmospheres. An important ambiguity remains as to whether all variability in ultra-cool dwarfs is caused by patchy clouds, or other fenomena like magnetic activity and auroras. Simultaneous multi-wavelength photometric and/or spectroscopic monitoring could help to reveal this enigma.