Telescopes

The fading light of supernova SN 2025kg, followed by the fast X-ray transient EP 250108a, as seen by the Gemini North and South telescopes

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Two articles accepted for publication in “The Astrophysical Journal Letters” report different aspects of the study of supernova SN 2025kg, which generated a so-called fast X-ray transient, a little-known event that in this case was cataloged as EP 250108a. This type of event has now been described as a sort of stifled-at-birth version of a gamma-ray burst.

Two teams of researchers with several members in common used data collected by two instruments on the Einstein Probe space telescope and other instruments to analyze the emissions from this supernova. This allowed them to propose an explanation for the fast X-ray transients (FXTs) and how they differ from gamma-ray bursts.

Interstellar comet 3I/ATLAS

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Several scientific organizations have announced the detection of what appears to be an interstellar comet, which has consequently received the designation 3I/ATLAS. It could be a large comet, with an estimated width of around 20 kilometers, but the first estimates of the size of its nucleus are still very rough. Its trajectory will take it within the orbit of Mars, but, together with its considerable speed, it will only lead to a limited direction change by the Sun’s gravity. Unfortunately, it will never get close enough to Earth to allow detailed observations, but any interstellar object is very interesting for astronomers. This is the third officially recognized “visitor” after 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.

ASKAP J1832-0911 (in the circle) (Image X-ray: NASA/CXC/ICRAR, Curtin Univ., Z. Wang et al.; Infrared: NASA/JPL/CalTech/IPAC; Radio: SARAO/MeerKAT; Image processing: NASA/CXC/SAO/N. Wolk)

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An article published in the journal “Nature” reports a study on ASKAP J1832-0911, or simply ASKAP J1832, an object whose nature is still uncertain. A team of researchers combined data collected by different instruments, including NASA’s Chandra X-ray Observatory and the ASKAP radio telescope, to detect the emissions coming from this object. This allowed them to reveal anomalies with respect to the categories considered to try to identify it.

The radio emissions led to cataloging it as a long-period radio transient, but ASKAP J1832 has variable emissions of the same duration in X-rays as well. An object with that type of emissions has never been found before, so it arouses a lot of curiosity. It could be a magnetar or a white dwarf with a companion star, but its behavior remains strange, so the investigations will continue.

The Magellanic Clouds as seen by the Gaia space probe (Image ESA)

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An article published in “The Astrophysical Journal Letters” reports the results of a study of the Small Magellanic Cloud that shows how this dwarf galaxy is undergoing distortions in its shape due to various gravitational influences. Satoya Nakano and Kengo Tachihara of Nagoya University, Japan, used data collected by ESA’s Gaia space probe together with information on Cepheid stars collected by the OGLE (Optical Gravitational Lensing Experiment) project. This allowed them to determine the distances of 4,236 Cepheids and the anomalies in their motions. The conclusion is that the Small Magellanic Cloud is undergoing a gravitational influence from the Large Magellanic Cloud and another as yet unknown source.

On the left the supernova SN 1987A remnant as seen by the James Webb Space Telescope, and in the other two panels the simulation of the density distribution of the remnant, which include the iron-rich materials, and the current morphology of that remnant

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An article to be published in the journal “Astronomy & Astrophysics” reports a study of the supernova SN 1987A that offers evidence that the explosion was decidedly asymmetric and dominated by two bipolar jets. A team of researchers led by astrophysicist Salvatore Orlando of the Italian National Institute of Astrophysics in Palermo has developed a model that takes into account the interaction between matter and magnetic field to study the evolution of SN 1987A. The results successfully reproduce the morphology of the iron-rich ejected materials, which was observed in particular by the James Webb Space Telescope. This shows that those structures are the result of an asymmetric explosion.