Context. The Metis coronagraph is one of the remote sensing instruments of the ESA-NASA Solar Orb... more Context. The Metis coronagraph is one of the remote sensing instruments of the ESA-NASA Solar Orbiter mission. The goal for the instrument is to enable the study of the solar atmosphere and solar wind by simultaneously acquiring images of the solar corona at two different wavelengths: visible light (VL), within a band ranging from 580 nm to 640 nm, and ultraviolet light, in the HI Lyα 121.6 ± 10 nm. The visible-light channel of the coronagraph includes a polarimeter with electro-optically modulating liquid crystal variable retarders to measure the linearly polarized brightness of the K-corona and derive the electron density. Aims. In this paper, we present the first in-flight validation results of the Metis polarimetric channel together with a comparison to the on-ground calibrations. This paper seeks to validate the first use of an electro-optical device, the liquid crystal-based polarimeter, in deep space and within a hard radiation environment. Methods. We used the orientation of...
Galactic cosmic-ray (GCR) energy spectra in the heliosphere vary on the basis of the level of sol... more Galactic cosmic-ray (GCR) energy spectra in the heliosphere vary on the basis of the level of solar activity, the status of solar polarity and interplanetary transient magnetic structures of solar origin. A high counting rate particle detector (PD) aboard LISA Pathfinder (LPF) allows for the measurement of galactic cosmic-ray and solar energetic particle (SEP) integral fluxes at energies > 70 MeV n−1 up to 6500 counts s−1. Data are gathered with a sampling time of 15 s. A study of GCR flux depressions associated with the third harmonic of the Sun rotation period (~ 9 days) is presented here.
Context.The Metis coronagraph on board Solar Orbiter offers a new view of coronal mass ejections ... more Context.The Metis coronagraph on board Solar Orbiter offers a new view of coronal mass ejections (CMEs), observing them for the first time with simultaneous images acquired with a broad-band filter in the visible-light interval and with a narrow-band filter around the H ILy-αline at 121.567 nm, the so-called Metis UV channel.Aims.We show the first Metis observations of a CME, obtained on 16 and 17 January 2021. The event was also observed by the EUI/FSI imager on board Solar Orbiter, as well as by other space-based coronagraphs, such as STEREO-A/COR2 and SOHO/LASCO/C2, whose images are combined here with Metis data.Methods.Different images are analysed here to reconstruct the 3D orientation of the expanding CME flux rope using the graduated cylindrical shell model. This also allows us to identify the possible location of the source region. Measurements of the CME kinematics allow us to quantify the expected Doppler dimming in the Ly-αchannel.Results.Observations show that most CME f...
Galactic (GCR) and solar cosmic rays with energies larger than 100 MeV(/n) penetrate and charge t... more Galactic (GCR) and solar cosmic rays with energies larger than 100 MeV(/n) penetrate and charge the test masses of the LISA missions. Spurious forces between the test-masses and the surrounding electrodes might be mistaken for genuine gravitational wave signals. In this paper, we report about galactic and interplanetary cosmic rays charging the LISA test-masses as a function of the solar
Context. The Metis coronagraph is one of the remote sensing instruments of the ESA-NASA Solar Orb... more Context. The Metis coronagraph is one of the remote sensing instruments of the ESA-NASA Solar Orbiter mission. The goal for the instrument is to enable the study of the solar atmosphere and solar wind by simultaneously acquiring images of the solar corona at two different wavelengths: visible light (VL), within a band ranging from 580 nm to 640 nm, and ultraviolet light, in the HI Lyα 121.6 ± 10 nm. The visible-light channel of the coronagraph includes a polarimeter with electro-optically modulating liquid crystal variable retarders to measure the linearly polarized brightness of the K-corona and derive the electron density. Aims. In this paper, we present the first in-flight validation results of the Metis polarimetric channel together with a comparison to the on-ground calibrations. This paper seeks to validate the first use of an electro-optical device, the liquid crystal-based polarimeter, in deep space and within a hard radiation environment. Methods. We used the orientation of...
Galactic cosmic-ray (GCR) energy spectra in the heliosphere vary on the basis of the level of sol... more Galactic cosmic-ray (GCR) energy spectra in the heliosphere vary on the basis of the level of solar activity, the status of solar polarity and interplanetary transient magnetic structures of solar origin. A high counting rate particle detector (PD) aboard LISA Pathfinder (LPF) allows for the measurement of galactic cosmic-ray and solar energetic particle (SEP) integral fluxes at energies > 70 MeV n−1 up to 6500 counts s−1. Data are gathered with a sampling time of 15 s. A study of GCR flux depressions associated with the third harmonic of the Sun rotation period (~ 9 days) is presented here.
Context.The Metis coronagraph on board Solar Orbiter offers a new view of coronal mass ejections ... more Context.The Metis coronagraph on board Solar Orbiter offers a new view of coronal mass ejections (CMEs), observing them for the first time with simultaneous images acquired with a broad-band filter in the visible-light interval and with a narrow-band filter around the H ILy-αline at 121.567 nm, the so-called Metis UV channel.Aims.We show the first Metis observations of a CME, obtained on 16 and 17 January 2021. The event was also observed by the EUI/FSI imager on board Solar Orbiter, as well as by other space-based coronagraphs, such as STEREO-A/COR2 and SOHO/LASCO/C2, whose images are combined here with Metis data.Methods.Different images are analysed here to reconstruct the 3D orientation of the expanding CME flux rope using the graduated cylindrical shell model. This also allows us to identify the possible location of the source region. Measurements of the CME kinematics allow us to quantify the expected Doppler dimming in the Ly-αchannel.Results.Observations show that most CME f...
Galactic (GCR) and solar cosmic rays with energies larger than 100 MeV(/n) penetrate and charge t... more Galactic (GCR) and solar cosmic rays with energies larger than 100 MeV(/n) penetrate and charge the test masses of the LISA missions. Spurious forces between the test-masses and the surrounding electrodes might be mistaken for genuine gravitational wave signals. In this paper, we report about galactic and interplanetary cosmic rays charging the LISA test-masses as a function of the solar
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