Stellar flares have been detected using GPS signals

The technique allows not only the detection and measurement of the stellar flare intensity, but also the estimated position of the source

Manuel Hernández-Pajares, researcher from the Institute of Space Studies of Catalonia (IEEC) at the Space Sciences and Technologies Research Group (CTE-CRAE) of the Universitat Politècnica de Catalunya · BarcelonaTech (UPC), in collaboration with David Moreno-Borràs, recently graduated in Computer Engineering at the Faculty of Informatics of Barcelona (FIB), and also current member of IEEC, has developed a technique that allows to detect stellar flares using the signals emitted by satellite navigation systems, popularly known as GPS (Global Positioning System).

Stellar flares are sudden electromagnetic emissions in certain areas of the star surface that release large amounts of energy. When these emissions reach our planet, they generate an ion discharge, which causes a sudden over-ionization in the upper part of the Earth's atmosphere (the ionosphere).

“The easiest way to explain what we have done is to compare it to Chinese shadows: instead of directly observing the phenomenon, what we do is looking at the shadow, the imprint that the sudden fluctuation of a part of the stellar radiation leaves on the atmosphere”, explains Hernández-Pajares, also head of the research group Ionospheric determination and navigation based on Satellite and Terrestrial systems (IonSAT) at UPC. "We do that using satellite navigation systems, what we know as GPS."

This method allows the detection of sudden increases in star radiation using only measurements from the Global Navigation Satellite Systems (GNSS), such as the GPS ones. Until now, the stellar flares were detected in the Sun through space probes such as the SOHO (Solar and Heliospheric Observatory) – a joint mission of the European Space Agency (ESA) and NASA –, or by telescopes such as Swift or Fermi, both from NASA, which can detect flares in other stars.

The technique developed allows not only the detection and measurement of the flare intensity, but also the approximated estimation of the source position in the celestial sphere with an uncertainty of only a few degrees. This technique opens the door to a new kind of astronomy for the detection and study of these phenomena: a new method using real-time and open-access data thanks to the permanent GNSS receivers distributed around the world.

Caption: Imprint on the rate of change in the ionization level of the upper part of the Earth's atmosphere (ionosphere) in the vertical of the star Proxima Centauri, probably due to a large flare that showed on 18 March 2016
Credits: UPC

First test: possible detection of solar flares in 2012

These results have been made possible thanks to the refinement of the technique previously developed by Dr. Hernández-Pajares to detect and measure solar flares of strong, medium and weak intensity. This technique is currently being implemented, in real time, in an ESA’s project that is part of the Space Situational Awareness program. The developed algorithm has been verified with two more distant stellar flares and therefore more difficult to detect: one in the star Proxima Centauri (detected on 18 March 2016) and the other one in the star NGTS J121939.5-355557 (detected on 1 February 2016). The estimates obtained with the algorithm have been successfully contrasted with those of studies that use conventional astronomical techniques.

One step further: identifying the habitability of exoplanets

The researchers have started a new ESA-funded project to confirm the new technique and determine whether it could open up a new field of exploration of stellar activity measurements, with potential applications, such as estimating the habitability of exoplanets, among others.

"This energy source that we indirectly detect with GPS – the sudden increase of the photon flux in the extreme ultraviolet band – is one of the key elements in determining whether these exoplanets could have habitable conditions," explains the researcher.

* Press release from the Universitat Politècnica de Catalunya · BarcelonaTech (UPC) in collaboration with IEEC Communication Office.

Links

– IEEC
– UPC
– Grup de recerca CTE-CRAE

More information

This research is presented in a paper entitled “Real-time detection, location and measurement of geoeffective stellar flares from Global Navigation Satellite System data: new technique and case studies”, by M. Hernández-Pajares and D. Moreno-Borràs, which appeared in the journal Space Weather of American Geophysical Union on 22 February 2020.

The Institute of Space Studies of Catalonia (IEEC  — Institut d’Estudis Espacials de Catalunya) promotes and coordinates space research and technology development in Catalonia for the benefit of society. IEEC fosters collaborations both locally and worldwide and is an efficient agent of knowledge, innovation and technology transfer. As a result of 25 years of high-quality research, done in collaboration with major international organisations, IEEC ranks among the best international research centers, focusing on areas such as: astrophysics, cosmology, planetary science, and Earth Observation. IEEC’s engineering division develops instrumentation for ground- and space-based projects, and has extensive experience in working with private or public organisations from the aerospace and other innovation sectors.  

IEEC is a private non-profit foundation, governed by a Board of Trustees composed of Generalitat de Catalunya and four other institutions that each have a research unit, which together constitute the core of IEEC R&D activity: the University of Barcelona (UB) with the research unit ICCUB — Institute of Cosmos Sciences; the Autonomous University of Barcelona (UAB) with the research unit CERES — Center of Space Studies and Research; the Polytechnic University of Catalonia (UPC) with the research unit CTE — Research Group in Space Sciences and Technologies; the Spanish Research Council (CSIC) with the research unit ICE — Institute of Space Sciences. IEEC is a CERCA (Centres de Recerca de Catalunya) center.

Main image

Image: solar-flare-NASA.jpg
Caption: Image of a solar flare captured by NASA's Solar Dynamics Observatory (SDO) in 2017.
Credits: NASA/SDO/Goddard.

Contacts

IEEC Communication Office
Barcelona, Spain
Ana Montaner 
E-mail: comunicacio@ieec.cat 

Lead Researcher
Barcelona, Spain
Manuel Hernández-Pajares
Space Sciences and Technologies Research Group (CTE-CRAE) of UPC
Institute of Space Studies of Catalonia (IEEC)
E-mail: manuel.hernandez@upc.edu; hernandez@ieec.cat