Found 3 talks width keyword helioseismology

Durante los últimos 45 años, el grupo de Sismología Solar (y Estelar y Búsqueda de Exoplanetas) del Instituto de Astrofísica de Canarias, ha estado observando ininterrumpidamente los patrones espaciales y temporales de vibración del Sol. He estado involucrado en esta increíble aventura durante los últimos 30 años, intentando relacionar las frecuencias de oscilación del sol con su estructura y dinámica internas. En este seminario, me gustaría mostrarles aquellos aspectos científicos, instrumentales y humanistas que más me han llamado la atención a lo largo de estos años, poniendo especial relevancia en las contribuciones del grupo de investigación y de su fundador, el profesor Teodoro Roca Cortés. 

Mark I is a part of the origin of the IAC, operating in the El Teide Observatory since 1975, in three different locations until reaching the Solar Pyramid "van der Raay" in 1987. Every day, weather permitting, it has been providing precise measurements of the radial velocity of our star. It began to perform continuous daily observations from July 1984 and, until December 2020, 10169 out of 13408 possible days (76%) useful data has been gathered. Designed, updated, maintained and operated by the Helioseismology team at the IAC and the University of Birmingham (UK), more than 100 people, from TOTs and weekend fellows to professors, have contributed to this endeavour. It was a true pioneer, key in the birth and development of Helioseismology and Astroseismology as branches of modern Astronomy.

Mark I is a resonant scattering spectrophotometer that measures the radial velocity of integral sunlight using the KI-769.9 nm spectral line. It has been a pioneer and reference for calibration of other instruments: MarkII, IRIS, Cannon, Stellar, Space, BiSON, GOLF, which have also worked in different ground-based observatories and in space missions such as SoHO (1995-).

Its precision, in a single measurement of the solar radial velocity, is less than 1 m/s, and the one achieved so far is less than 1 cm/s at frequencies around 0.1 mHz (gravity modes zone) and less than 1 mm/s at 3 mHz (acoustic modes zone). It measured for the first time the spectrum of solar acoustic modes (from 1.8 to 4.2 mHz) of small degree (ℓ <= 3): their frequencies, amplitudes and lifetimes, their rotational splitting; also its variations with the cycle of solar activity. He has explored gravity modes, measured the spectrum's background, and determined the acoustic cut-off frequency in the solar photosphere. All this has led to numerous discoveries that have been published in around 40 doctoral theses at different universities and more than 600 papers in international journals and books. These works have been already cited around 10,000 times in scientific literature.

In this talk I will briefly review its history throughout more than 45 years, an entire academic life, and I will raise some suggestions on its scientific use from now on.

The Sun is a magnetic star, not as magnetic as some stars, or as it was when it
was younger, but nonetheless magnetic fields dominate and even construct its
atmosphere. There would be no corona without magnetic fields. The surface is
also dappled with small scale magnetic field associated with surface convection
cells, granules and supergranules. But sometimes we also see much larger and
more powerful Active Regions containing sunspots. These are wounds in the
surface of the Sun that allow waves and oscillations in the solar interior and
atmosphere to be coupled much more directly than they usually are. In
particular, they allow the Sun's internal seismology (the p-modes) to drive a
variety of waves through the Active Region atmosphere, and conversely, the
atmospheres to pollute the internal seismology. This makes active region
helioseismology a very challenging field.