Observando la cromosfera solar en el infrarrojo

The solar chromosphere has historically been studied from spectral lines in the visible and UV, notably H{\alpha}, Ca ii, Mg ii and Ly{\alpha}. Observations at long UV wavelengths (304, 1600 and 1700 {\AA}) from space have been recently added. However, the chromosphere can also be studied in the infrared (IR), both in the continuum as in the lines. Studies in this spectral band, which by definition extends from 1 {\mu}m to 1 mm, are scarce and recent, and its advantages having been little explored. In this work we present a review of what has been done and detail how much can be done with ground-based instruments. Argentina has a set of unique telescopes for the observation of the chromosphere, some with more than 20 years of operation and in process of renovation, others recently installed and still some in development. The panorama is very encouraging and allows to anticipate a strong international cooperation with other ground and space facilities.Comment: Accepted in the Bolet\'in de la Asociaci\'on Argentina de Astronom\'ia, 2023. In Spanish. 7 pages, 8 figure

Estimating the Coronal Supra-Arcade Downflow Radio Emission: From Centimeter Through Submillimeter Wavelengths

Supra-arcade downflows (SADs) are infrequent, wiggly, and low-emission structures observed to descend through the solar corona, mostly in EUV and soft X-ray frequencies. Based on their physical characteristics, SADs have been interpreted as low-density bubbles and are related to magnetic reconnection processes during long-term erupting flares. In this work, we use numerical MHD simulations to compute flux density maps, which are convolved with telescope beams to synthesize images with the aim to assess the expected SAD emission in radio wavelengths. We assume that the emission is thermal bremsstrahlung from a fully ionized plasma and without any appreciable gyroresonance contribution since magnetic fields are of the order of 10 G. We find that SAD emission should be optically thin in the frequency range of [10–1,000] GHz, and the spatially integrated flux should be larger than 1 Jy. We conclude, therefore, that SADs consistently are less bright than the surrounding fan and that observing SADs in radio frequencies between [0.5–1,000] GHz is feasible with present instrumentation. The observing strategies are proposed, including the instruments that can be used. Moreover, since the emission is, for the most part, optically thin, the flux density is proportional to temperature, density, and line-of-sight depth and when combined with EUV and soft X-ray images may allow a better density and temperature determination of SADs.Fil: Zurbriggen, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Universidade Presbiteriana Mackenzie; BrasilFil: Giménez de Castro, C. Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Costa, Andrea. Universidade Presbiteriana Mackenzie; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Cécere, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Selhorst, Caius L.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Solar Submillimeter Telescope next generation

The Solar Submillimeter Telescope (SST) is an unique instrument that has been observing the Sun daily since 2001 bringing a wealth of information and raising new questions about the particle acceleration and transport, and emission mechanisms during flares. We are now designing its successor, the SSTng, that will expand the scientific goals of the instrument, including non-solar source observations.Comment: Accepted for the URSI GASS 2023, Sapporo, japan, 19-26 August 2023. 4 pages, 4 figure

Launch of solar coronal mass ejections and submillimeter pulse bursts

The rapid solar spikes (100-500 ms) recently discovered at submillimeter waves bring new possibilities to investigate energetic processes near the solar surface that might have an important role in the launch and propelling of ionized mass away from the Sun. We present a study on the association between the launch time of coronal mass ejections (CMEs) observed by the LASCO instruments on the SOHO spacecraft and the onset of the new kind of rapid solar spikes (100-500 ms) observed at submillimetric waves (212 and 405 GHz) by the new Solar Submm-wave Telescope (SST). We investigated six submm-wave events, all found associated to CMEs. Seven related CME were identified. Five of them were associated with flares with large GOES class soft X-rays, presenting distinct time histories and associations at other energy ranges, and two of them were related to flares behind the solar limb, with simultaneous related activity observed in the visible solar disk. Ultraviolet images from EIT on SOHO show some kind of small or large-scale magnetic activity or brightening for all events. The extrapolation of apparent CME positions to the solar surface show that they occurred nearly coincident in time with the onset of submm-wave pulses for all six events. These results suggest that pulse bursts might be representative of an important early signature of CMEs, especially for events beginning near the center of the solar disk, sometimes identified as "halo" CMEs. They lead to several challenging questions relative to the physical nature of the pulses and its association to the launch and acceleration of coronal mass ejections. Although these evidences may favor multiple rapid energy releases at the origin near the solar surface, they require further research in order to better understand both diagnostics and model descriptions.Fil: Kaufmann, Pierre. Universidade Estadual de Campinas; Brasil. Universidade Presbiteriana Mackenzie; BrasilFil: De Castro, C. Guillermo Giménez. Universidade Presbiteriana Mackenzie; BrasilFil: Makhmutov, Vladimir S.. Universidade Presbiteriana Mackenzie; Brasil. The Russian Academy Of Sciences; RusiaFil: Raulin, Jean Pierre. Universidade Presbiteriana Mackenzie; BrasilFil: Schwenn, Rainer. Max Planck Institute For Solar System Research; AlemaniaFil: Levato, Orlando Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Rovira, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

LLAMAS: An acquisition, control and monitoring software for LLAMA

The Large Latin American Millimeter Array is a 12?m Nasmyth antenna to be installed at 4850 m above see level in the Argentinian Atacama Region. LLAMA will operate both in single dish mode and as a VLBI station. LLAMAS is the software, under development, that will acquire the data from the receivers, control the different devices and monitor the safe functioning of the sub-parts. It is based on the ALMA Common Software (ACS), that implements the concept of containers and distributed component objects. It is programmed in JAVA, C++ andPython, and uses the Common Object Request Broker Architecture (CORBA) infrastructure to exchange messages between the subsystems. LLAMAS must be as heterogeneous as the telescope operation: single dish observing modes with simultaneous readouts from single-pixel receivers, and two different polarization channels in continuum (total?power) or spectral mode, single-dish from multi-pixel cameras, and coordinated interferometric observations as a VLBI station. Since the antenna will be located at a very high altitude, the control room will be at a safer lower place 20 km away, and therefore the operation will be remote. Moreover, the high altitude requires the use of disk-less computers and the immediate data transfer to the control room through a fast connection link. It is also envisaged a Web based observing proposal submission and data querying system for the astronomers, making the whole observing process world wide available. In this work we present the conceptual software design of the observation cycle, that we call from the Astronomer to the Astronomer (A2A), and we describe the different subsystems needed to accomplish this goal.Fil: Giménez de Castro, Guillermo C.. Universidade Presbiteriana Mackenzie; BrasilFil: Larrarte, Juan Jose. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Ibsen, J. J.. Atacama Large Millimiter/submillimeter Array; ChileFil: Abraham, Zulema. Universidade do Sao Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; BrasilFil: Bareilles, Federico Ariel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Hauscarriaga, Fernando Pablo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Strauss, C.. National Institute For Space Research; BrasilFil: Zanella, D.. Universidade do Sao Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; BrasilXXXIX Reunião Anual da Sociedade Astronômica BrasileiraOuro PretoBrasilSociedade Astronômica Brasileir

The Long Latin American Millimeter Array: a new submillimeter facility to observe the Sun

The Long Latin American Millimeter Array (LLAMA), is an Argentinian - Brazilian project to build and operate a 12-m radiotelescope that may observe from 45 to 900 GHz and that will have VLBI capabilities. LLAMA will be installed in the Argentinian "Puna de Atacama" region at 4800 m above see level in the Salta Province, at less than 200 km distance from ALMA. The site has excellent sky transmission characteristics for submillimeter astronomy. LLAMA may observein single dish mode, or as VLBI station associated to ALMA at submillimeter wavelengths or to other telescopes at microwaves. Since it is a multipurpose observatory,it has within its objectives,observing the Sun. In VLBI mode it will have a resolution better than 0.001 arcsec at 1 mm wavelength, bringing unprecedented images of the solar atmosphere with a spatial resolution of the order of 1 km. In single dish mode, it will complement spectral observations already carry out by other telescopes. Key aspects to be addressed by solar LLAMA observations are: i) low atmosphere structure, ii) filaments, iii) dynamics of the chromosphere and its magnetic field and iv) flares. The project received full financial support from the Brazilian Agency FAPESP and the Argentinian Ministry of Science for the installation and operation of the antenna near thetown of San Antonio de los Cobres, and should have its first light by beginning 2015, expecting to start early science on middle 2016. We detail in this work the technical features of LLAMA, its state of advance and the science that may be done with its observations.Fil: Giménez de Castro, Guillermo C.. Universidade Presbiteriana Mackenzie; BrasilFil: Abraham, Zulema. Universidade do Sao Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; BrasilFil: Arnal, Edmundo Marcelo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Gouveia Dal Pino, Elizabete de. Universidade do Sao Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; BrasilFil: Larrarte, Juan Jose. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Lepine, Jacques. Universidade do Sao Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; BrasilFil: Morras, Ricardo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Viramonte, Jose Maria. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; Argentina2nd Solar ALMA WorkshopPragaRepública ChecaAcademy of Sciences of the Czech Republic. Astronomical Institut

Rapid pulsations in sub-THz solar bursts

A new solar burst emission spectral component has been found showing sub-THz fluxes increasing with frequency, spectrally separated from the well known microwave component. Rapid pulsations are found present in all events observed at the two frequencies of the solar submillimeter-wave telescope (SST): 212 and 405 GHz. They were studied in greater detail for three solar bursts exhibiting the new THz spectral component. The pulse amplitudes are of about 5-8% of the mean flux throughout the bursts durations, being comparable for both frequencies. Pulsations range from one pulse every few seconds to 8-10 per second. The pulse repetition rates (R) are linearly proportional to the mean burst fluxes (S), following the simple relationship S = k R, suggesting that the pulsations might be the response to discrete flare particle accelerator injections quantized in energy. Although this result is consistent with qualitative trends previously found in the GHz range, the pulse amplitude relative to the mean fluxes at the sub-THz frequencies appear to be nearly ten times smaller than expected from the extrapolation of the trends found in the GHz range. However there are difficulties to reconcile the nearly simultaneous GHz and THz burst emission spectrally separated components, exhibiting rapid pulsations with considerably larger relative intensities in the GHz range.Comment: 9 pages and 11 figures, submitted to Astrophys. J; Revised version accepted by ApJ on 4 March 200

The Submillimeter Active Region Excess Brightness Temperature during Solar Cycles 23 and 24

We report the temporal evolution of the excess brightness temperature above solar active regions (ARs) observed with the Solar Submillimeter Telescope (SST) at 212 ({\lambda} = 1.4 mm) and 405 GHz ({\lambda} = 0.7 mm) during Cycles 23 and 24. Comparison with the sunspot number (SSN) yields a Pearson's correlation coefficient R = 0.88 and 0.74 for 212 and 405 GHz, respectively. Moreover, when only Cycle 24 is taken into account the correlation coefficients go to 0.93 and 0.81 for each frequency. We derive the spectral index {\alpha} between SST frequencies and found a slight anti-correlation with the SSN (R = -0.25); however, since the amplitude of the variation is lower than the standard deviation we cannot draw a definite conclusion. Indeed, {\alpha} remains almost constant within the uncertainties with a median value approximate to 0 characteristic of an optically thick thermal source. Since the origin of the AR submillimeter radiation is thermal continuum produced at chromospheric heights, the strong correlation between the excess brightness temperature and the magnetic cycle evolution could be related to the available free magnetic energy to be released in reconnection events.Comment: Accepted for publication in the Astrophysical Journa