Calar Alto Observatory: at the forefront of galaxy sampling and the search for extrasolar planets

The dome of the 3.5-metre telescope at Calar Alto Observatory today hosted the launch of CALIFA and CARMENES, two international projects that are benchmarks in their respective fields.

Observations will be continuing throughout June for the CALIFA galaxy-sampling project, which will enable the structure and evolution of galaxies to be determined in unprecedented retail, to serve as an international point of reference for the next decade.

At the same time, in the white rooms of the Andalusian Astrophysics Institute (IAA-CSIC) the final touches are being made to CARMENES, the instrument that will search for Earth-like planets from Calar Alto (Sierra de los Filabres, Gérgal, Almería).

The two international projects, which are being led from Granada by researchers at the Andalusian Astrophysics Institute, are part of the contribution made by the international community at Calar Alto Observatory (CAHA). Both were presented this morning in a striking location: beneath the dome of the observatory’s 3.5-metre telescope.

Involved in the event were Francisco Triguero, the Andalusian Regional government’s general secretary for universities, research and technology; José Manuel Vílchez, director of the Andalusian Astrophysics Institute; Jordi Torra, manager of the astronomical infrastructure network at the Ministry of Finance and Competition; Jesús Aceituno, deputy director of Calar Alto Observatory;  Enrique Pérez, an IAA-CSIC researcher and member of the CALIFA team; and Pedro J. Amado, the lead researcher for the CARMENES project in Spain.

During the presentation particular emphasis was placed on the excellence and international impact of the two projects, as well as the suitability of the facilities at Calar Alto for projects of this size. It is the only observatory that can provide the Spanish astronomy community with more than 180 nights of telescope observations per year.

"Paradoxically, the scientific boom at the Observatory has coincided with period of budget cuts that have nothing to do with its excellent performance,” José Manuel Vílchez, director of the Andalusian Astrophysics Institute, said. “Projects like CALIFA and CARMENES show just how robust the observatory is, the quality of its facilities and instruments and how effective its personnel are. Calar has been a major driving force for Spanish astronomy and we must do everything we can to keep it that way.”

Jesús Aceituno, the observatory’s deputy director, also commented on this issue. “To date, despite the cuts, we’ve been able to meet all our commitments thanks to the efforts of the staff to make sure than no observing nights were lost.” The deputy director also praised the exceptional characteristics of the Observatory and its skies, as well as the excellence of its instruments. He also announced future CAHA projects with International organisations including the European Space Agency (ESA) and the InnoFSPEC-AIP technology institute in Potsdam.

“Here we've learned that it was possible to have telescopes like the ones we saw in books from abroad. We all owe to Calar Alto the fact that Spain is now one of the leading countries in the field of astronomy,” Jordi Torra, manager of the astronomical infrastructure network of the Ministry of Finance and Competition, said. “Calar Alto is one of the observatories with the most synergies with other national and international institutions. It also produces high-quality publications and is widely recognised internationally,” he added.

“Calar Alto has a future,” Francisco Triguero, the Andalusian Regional Government’s general secretary for universities, research and technology, stressed. “Its future is in its capacity to obtain resources, in the performance of its personnel, in the quality of its facilities and in the commitment made by public authorities to work to solve the problems at the Observatory.”

The event was also attended by Adrian Valverde, the Almería Delegate of the Andalusian Regional Ministry of Finance, Innovation, Science and Employment; Javier Gorgas, chair of the Spanish Astronomy Society; and Martin Roth, director of the InnoFSPEC-AIP technology institute in Potsdam, who built the PPAK instrument being used for CALIFA.

CALIFA: 3D SPECTROSCOPY TO REVEAL HOW GALAXIES EVOLVE

Galaxies are large clusters of stars, gas and dust, and dark matter. We know that they grow by converting gas into successive generations of stars, and also that the largest galaxies achieved their size by merging with smaller galaxies. But how can we unravel the history of galaxies and understand their diversity?

Sampling of galaxies has addressed this problem either by turning to imaging to obtain detailed information on galactic structure or by using spectroscopy, which reveals the physical properties of galaxies (composition, temperature, age, etc.), but without bounding these feature within specific regions or by sampling only limited areas of galaxies. And this results in observational bias.

CALIFA, however, obtains one thousand spectra per galaxy, enabling use to learn about galaxies with a level of detail that previously would have been inconceivable. Also, CALIFA provides data on the evolution of each galaxy over time. It tells us when and how gas turned into stars during each stage and also reveals the evolution of the galaxy in each of its regions over the course of ten billion years.

Finally, CALIFA allows us to determine the evolution in mass, brightness and chemicals elements of all six hundred galaxies in the sample. It has thus been found that more massive galaxies grow more quickly than smaller ones, and that they grow outwards, forming their central regions first. Results have also been obtained on how the chemical elements necessary for life are created inside galaxies, and also on the phenomena that are involved in galactic collisions. We have even been able to observe directly the latest generation of stars to be born, still inside their formation nests.

CALIFA is a “legacy project”, inasmuch as it includes an undertaking to release its data and make it available to the whole scientific community. As such, it is considered to be an international benchmark for the coming decade.

THE SEARCH FOR "EXOWORLDS" WITH CARMENES

As planets revolve around their star, they cause the star to wobble slightly. These oscillations, if measured with sufficient precision, reveal the presence of those planets, even if we cannot see them directly. This is how CARMENES will look for other planets that are similar to Earth. 

CARMENES is not only the first instrument proposed by Spain to be installed at the Calar Alto Observatory but it is also unique anywhere in the world, in terms of both its precision and its stability: qualities that are indispensable when it comes to measuring the tiny variations in speed that planets produce in the stars that they orbit. Indeed, CARMENES poses a stimulating technological challenge, as it will detect speed variations in the movement of stars that are hundreds of billions of kilometres away with a precision of the order of one metre per second.

To achieve such levels of precision requires not just a sophisticated optical design, but also maintaining conditions of maximum stability in  the instrument’s operating environment, working in high-vacuum conditions with temperatures controlled electronically down to one hundredth of a degree. This has therefore posed challenge of the first order for the construction consortium, in which a key role has been played by Andalusia’s technological involvement.

CARMENES, which will operate on the 3.5-metre telescope at Calar Alto Observatory (Almería), is a project that has been devised by scientists and technologists at the Andalusian Astrophysics Institute (IAA-CSIC) in partnership with other Spanish and German institutions.