In the last two decades, space-based solar observatories turned out to be very suitable for comet research. Visible images taken by coronagraphs such as SOHO-LASCO C2/C3 or STEREO-SECCHI have allowed to discover and study many comets, almost all belonging to the "near-Sun comets" family [1]. Many comets have been also observed in the HI Lyman-? spectral line by the SOHO/ SWAN radiometer [2] or with the SOHO-UVCS spectrometer [3], allowing the study of their dynamical evolution of water production rates. Such observations can be of great interest also in solar physics, since a comet passing through the Sun's corona acts as a probe to estimate the plasma parameters at each point along its path, which is a useful complement to remote sensing. Comet C/2021 A1 (Leonard) is a long-period comet (LPC) which reached its perihelion at au on 2022 January 3. Serendipitously, the Metis coronagraph [4] onboard on ESA Solar Orbiter mission had the opportunity to perform the simultaneous imaging of this comet in linearly polarized visible light (VL) and in the ultraviolet (UV) around the HI Lyman-? (121.6 nm) spectral line, during a temporal window of about 12 hours, from 19.00UT on December 15 to 7.00UT on December 16 (see Figure 1). Such observations constitute the first-ever concurrent images of an LPC in such two spectral ranges, allowing the simultaneous study of the dust and neutral hydrogen coma.
Observation of comet C/2021 A1 (Leonard) with Metis coronagraph on board the Solar Orbiter mission
Alain Jody Corso;Vania Da Deppo;
2022
Abstract
In the last two decades, space-based solar observatories turned out to be very suitable for comet research. Visible images taken by coronagraphs such as SOHO-LASCO C2/C3 or STEREO-SECCHI have allowed to discover and study many comets, almost all belonging to the "near-Sun comets" family [1]. Many comets have been also observed in the HI Lyman-? spectral line by the SOHO/ SWAN radiometer [2] or with the SOHO-UVCS spectrometer [3], allowing the study of their dynamical evolution of water production rates. Such observations can be of great interest also in solar physics, since a comet passing through the Sun's corona acts as a probe to estimate the plasma parameters at each point along its path, which is a useful complement to remote sensing. Comet C/2021 A1 (Leonard) is a long-period comet (LPC) which reached its perihelion at au on 2022 January 3. Serendipitously, the Metis coronagraph [4] onboard on ESA Solar Orbiter mission had the opportunity to perform the simultaneous imaging of this comet in linearly polarized visible light (VL) and in the ultraviolet (UV) around the HI Lyman-? (121.6 nm) spectral line, during a temporal window of about 12 hours, from 19.00UT on December 15 to 7.00UT on December 16 (see Figure 1). Such observations constitute the first-ever concurrent images of an LPC in such two spectral ranges, allowing the simultaneous study of the dust and neutral hydrogen coma.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
