The Large Latin American Millimeter Array (LLAMA) is a single-dish 12 m Nasmyth optics antenna which is under construction in the

Puna de Atacama The Puna de Atacama or Atacama Plateau''Atacama Plateau''
article at the ''

Province of Salta,

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. The primary mirror accuracy will allow observation from 40 GHz up to 900 GHz. It is also planned to install a

bolometer A bolometer is a device for measuring radiant heat by means of a material having a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley. Principle of operation A bolometer ...

camera at millimeter wavelengths. After installation it will be able to join other similar instruments to perform Very Large Base Line Interferometry or to work in standalone mode. Financial support is provided by the Argentinian and Brazilian governments. The total cost of construction, around US$20 million, and operation as well as the telescope time use will be shared equally by the two countries. Construction planning started in July 2014 after the formal signature of an agreement between the main institutions involved.

Overview

LLAMA is a joint project between Argentinian and Brazilian Astronomers to build and operate a radio telescope at submillimeter wavelengths, that can work in stand alone mode or join a

Very Long Baseline Interferometry Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. T ...

(VLBI) network. The main scientific institutions involved in the project are the Argentine Institute of Radio Astronomy (IAR), and the Núcleo para o Apoio da Rádio Astronomia (NARA), from the Universidade de São Paulo (

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

). The telescope is located at a very high altitude (4,825 m) where the atmospheric absorption (mostly due to

water vapor (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous p ...

) allows the observation at the very short wavelengths of less than 1 mm. It is a multipurpose instrument that will have cryogenic receivers with very high sensitivity in order to observe very faint sources, and filters to observe the Sun.

History

The history of the instrument can be traced back to 2007, during the XII Latin American Regional IAU Meeting (LARIM) held in Isla de Margarita (

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

). Argentinian radio astronomers discussed the idea with colleagues from South America. The search for the best place for a submillimeter (wavelength less than 1 mm) telescope had started in Argentina in 2003, with a 210 GHz ''tipper'' which was installed in different places to investigate the atmospheric opacity. During the XXVII General Assembly in

Rio de Janeiro Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a ...

, the project gained a name in a document authored by the leading scientists of the project. In the same document, scientists also proposed the initial science, budget, strategies for construction, site, and other matters. The formal presentation before the Argentinian Science Ministry (MinCyT) was in 2010, while a meeting held at the offices of FAPESP in August 2011 was the kickoff in

. In 2011, MinCyT ranked LLAMA as its astronomical project and in 2012, FAPESP approved a €7 M grant. The final agreement, between MinCyT, FAPESP and Universidade de São Paulo (USP), was signed in June 2014, and on July 9, it was formally presented to the public. Measurements of the electrical characteristics of the site were carried out in late 2016, and construction of the road to the summit began in December 2016. Assembly of the antenna is planned to take place in 2022, with testing beginning in 2023.

Origin of the name

The observatory acronym comes from the Quechuan word ''llama'' that designates the South American camelid that lives in the region where the telescope is being installed. There is some confusion with the word ''array'', since LLAMA will consist of a single dish antenna, but the instrument will have VLBI technology and can therefore be part of an antenna array with telescopes of other observatories. Moreover, the LLAMA observatory can be expanded in the future by installing other antennas in different sites. In different official documents the acronym LLAMA may be found expanded as ''Long Latin American Millimeter Array'' rather than ''Large''. It is also possible to read ''Millimetric'' instead of ''Millimeter''. After some debate, the LLAMA Executive Committee stated that ''Large Latin American Millimeter Array'' is the right expansion for the LLAMA acronym. The observatory logo has as symbols the

Southern Cross Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for ...

(upper right), a telescope sketch (bottom right), the acronym (upper left) and a

llama The llama (; ) (''Lama glama'') is a domesticated South American camelid, widely used as a meat and pack animal by Andean cultures since the Pre-Columbian era. Llamas are social animals and live with others as a herd. Their wool is soft ...

profile (bottom left). Although it changed with time, these symbols are present since the beginning. The image illustrating this page is the official logo since August 2014.

Science

LLAMA is a multipurpose instrument, with the capacity to both observe bright sources like the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

, and very weak sources very far from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. The following is a list of different subjects that will be addressed with LLAMA observations.

The Sun

In the unperturbed solar atmosphere, the shorter the wavelength the deeper the observation. Frequencies near the submillimeter range are produced in the lower chromosphere or the photosphere. Therefore, LLAMA observations will bring new information about the structure of the lower Solar Atmosphere, the active and quiescent filaments and the dynamics of the chromosphere and its magnetic field. The possibility to observe Solar Flares at high frequencies with a high sensitive instrument will give clues about the acceleration of the high energetic particles in the Sun, complementing results obtained with the Solar Submillimeter Telescope. In particular the still unexplained spectral inversion above ≈ 100 GHz. A possible experiment would be to make VLBI solar observations. For example, in a joint observation between LLAMA and some of the ALMA antennas, a spatial resolution of 0.001" would be achieved for λ ≈ 1 mm, corresponding to a distance of 700 m on the solar surface.

Planets

* Extra-solar planetary systems around stars near the Sun. * Proto-planetary disks in star located in the Solar neighborhood. * Near-Earth objects.

Stellar objects

* Star forming regions, young stellar objects, and mechanisms of the star formation. * Non-thermal processes in stellar magnetospheres. * Interaction of stars and remnants of supernova with the interstellar medium.

Astrophysical jets and maser emission

* Astrophysical jets. * Maser phenomena of the recombination lines of the hydrogen atom. * Maser emission in star-forming regions. * Maser emission in late stars stellar envelopes.

Galactic and Intergalactic interstellar medium

* Continuum radiation from extragalactic cold dust. * Molecular material in the direction of different stellar objects. * Intergalactic Medium using the detection of molecular absorption lines in the direction of quasars. * Cosmic background radiation.

Galaxies

* Search for CO in galaxies with high redshift. * Molecular abundance. * Active Galactic Nuclei (AGN). * Variation of the fundamental constants by the observation of gravitational lensing. * High redshifts of regions with very high rate of star formation. * Proto-clusters of galaxies. * Space-time distortion produced by massive black holes.

High energies

Optics, Receivers

The Nasmyth optics will allow the installation of up to as six different

heterodyne A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called ''heterodyning'', which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyning is u ...

receivers. There is a consensus for these receivers to use the same spectral bands as ALMA.ALMA frequency bands
/ref> With this scheme the Nasmyth cabins will allocate receivers for the bands It is intended to install a

multi-wavelength camera at the

Cassegrain focus The Cassegrain reflector is a combination of a primary concave mirror and a secondary convex mirror, often used in optical telescopes and radio antennas, the main characteristic being that the optical path folds back onto itself, relative to the ...

, or possibly a camera plus a small

array.

References

{{Portal bar, Argentina, Astronomy, Stars, Spaceflight, Outer space, Solar System, Education, Science Astronomical instruments Radio telescopes Submillimetre telescopes Interferometric telescopes Telescopes under construction Astronomical observatories in Argentina