The J-ALFIN project aims to trace the trails that stars leave in their surroundings, using the JAST80 telescope. This means going far beyond conventional observations. The wide field of view of the Javalambre Astrophysical Observatory’s telescope offers an expanded perspective, producing images like the one shown here, which rescale —and almost redraw— the Medusa Nebula (Abell 21). Located about 1,500 light-years away, it is named after the figure from Greek mythology because its bright gaseous filaments resemble the hair flowing from Medusa’s head.

This project, one of the four ongoing legacy surveys at CEFCA conducted with the JAST80, seeks to follow the traces of the final diffusion stages of a planetary nebula —similar to tracking the outer ripples left in water after a stone falls in, far from the point of impact. This wider view, capturing the matter expelled by stars, is obtained using four of the telescope’s narrow-band filters, including the H-alpha filter. The key lies in multi-hour exposures combined with Gnuastro, a new software capable of revealing extremely faint emission that had gone undetected until now.

J-ALFIN, led by Principal Investigator Martín A. Guerrero, with the collaboration of CEFCA researcher Mohammad Akhlaghi and IAA-CSIC researcher Faezeh Bidjarchian, aims to understand how a nebula may affect nearby stars and the surrounding interstellar medium. Studying the material and structures it emits provides insight into the composition of the progenitor star, revealing elements that once formed part of it before its final stages. Sepideh Eskandarlou and Raul Infante-Sainz, from CEFCA, are also members of J-ALFIN.

Gnuastro, the software used, is a free and open source collection of programs and libraries designed for the manipulation and analysis of astronomical data. It provides a common basic interface and runs on the GNU/Linux operating system. In 2023, it was recognized by Google when selected for its funding program, Google Summer of Code. Beyond its use at the Observatorio Astrofísico de Javalambre (OAJ), Gnuastro is also employed in other observatories and international research projects. Notable examples include collaborations of the European Space Agency in which CEFCA is involved, such as the ARRAKIHS mission, as well as its use in the James Webb Space Telescope and the Hubble Space Telescope. The project, led by Mohammad Akhlaghi, is developed within the Data Processing and Archiving Department (DPAD) at the Centro de Estudios de Física del Cosmos de Aragón (CEFCA).

More information about Gnuastro here.