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- Egron, E., et al.
(författare)
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Single-dish and VLBI observations of Cygnus X-3 during the 2016 giant flare episode
- 2017
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 471:3, s. 2703-2714
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Tidskriftsartikel (refereegranskat)abstract
- In 2016 September, the microquasar Cygnus X-3 underwent a giant radio flare, which was monitored for 6 d with the Medicina Radio Astronomical Station and the Sardinia Radio Telescope. Long observations were performed in order to follow the evolution of the flare on an hourly scale, covering six frequency ranges from 1.5 to 25.6 GHz. The radio emission reached a maximum of 13.2 +/- 0.7 Jy at 7.2 GHz and 10 +/- 1 Jy at 18.6 GHz. Rapid flux variations were observed at high radio frequencies at the peak of the flare, together with rapid evolution of the spectral index: a steepened from 0.3 to 0.6 (with S-nu alpha nu(-alpha)) within 5 h. This is the first time that such fast variations are observed, giving support to the evolution from optically thick to optically thin plasmons in expansion moving outward from the core. Based on the Italian network (Noto, Medicina and SRT) and extended to the European antennas (Torun, Yebes, Onsala), very long baseline interferometry (VLBI) observations were triggered at 22 GHz on five different occasions, four times prior to the giant flare, and once during its decay phase. Flux variations of 2 h duration were recorded during the first session. They correspond to a mini-flare that occurred close to the core 10 d before the onset of the giant flare. From the latest VLBI observation we infer that 4 d after the flare peak the jet emission was extended over 30 mas.
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2. |
- Baqué, Mickael, et al.
(författare)
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Biosignature stability in space enables their use for life detection on Mars
- 2022
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Ingår i: Science Advances. - : NLM (Medline). - 2375-2548. ; 8:36
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Tidskriftsartikel (refereegranskat)abstract
- Two rover missions to Mars aim to detect biomolecules as a sign of extinct or extant life with, among other instruments, Raman spectrometers. However, there are many unknowns about the stability of Raman-detectable biomolecules in the martian environment, clouding the interpretation of the results. To quantify Raman-detectable biomolecule stability, we exposed seven biomolecules for 469 days to a simulated martian environment outside the International Space Station. Ultraviolet radiation (UVR) strongly changed the Raman spectra signals, but only minor change was observed when samples were shielded from UVR. These findings provide support for Mars mission operations searching for biosignatures in the subsurface. This experiment demonstrates the detectability of biomolecules by Raman spectroscopy in Mars regolith analogs after space exposure and lays the groundwork for a consolidated space-proven database of spectroscopy biosignatures in targeted environments.
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3. |
- Paragi, Z., et al.
(författare)
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Radio and X-Ray Monitoring of SS433
- 2007
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Ingår i: Revista Mexicana de Astronomía y Astrofísica. ; 27, s. 222-224
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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