Via Google Meet, room: https://meet.google.com/qsd-xeyy-izg
(People outside INAF will need authorization from people already in the room in order to access: F. Landini will be in the room 10 minutes before the telecon official time).
Agenda:
- Welcome and introduction (F. Landini, 5 min)
- Metis overview (M. Romoli, 20 min)
- F corona extraction methods overview (Y. De Leo, 20 min)
- Modelling the F corona through the time correlation of the total and polarized brightness images (A. Burtovoi, 15 min)
- Simulations of the K+F corona to prepare the observations and analysis of the PSP and SOLO observations (P. Lamy, 20 min)
- Continuum imaging of the corona with eclipses (B. Boe, 15 min)
- Topical team discussion and proposals (All, 25 min)
Berlicki Arkadiusz, Boe Benjamin, Burtovoi Aleksandr, Casini Chiara, Capobianco Gerardo, Capuano Giuseppe, Da Deppo Vania, De Leo Yara, Fineschi Silvano, Lamy Philippe, Landini Federico, Naletto Giampiero, Maurizio Pancrazzi, Podladchikova Elena, Romoli Marco, Shestov Sergei, Slemer Alessandra, Spadaro Daniele, Stangalini Marco, Teriaca Luca, Ying Beili
FL set-up a website to keep a record of all presentations and notes (it has already been shared among participants).
https://sites.google.com/inaf.it/fcorona-tt/home-page
A shared drive has been created as well. Members with a Google account can make modifications in the drive. The link is enough for downloading even without signing in.
https://drive.google.com/drive/folders/1EQE9KfYweIpG3JS7Qc774k-TIaD6SEW2?usp=sharing
FL invites all to use the website as an exchange tool for science and technical useful documents, ideas, sketches, etc.
FL would have preferred to make it editable by everyone in this group. Unfortunately, due to the characteristics of Google sites, that was not possible (restricted access can be set for gmail addresses only) and the website is public. Please send FL anything you want to be published.
Main objective: find a F-Corona model and/or extraction method that can suit the Metis orbit, which corresponds to a very general approach to the F-Corona investigation.
Introduction on Metis design and capabilities.
Publication policy for TT included.
YDL presents an overview on models and extraction methods for the F-Corona. In addition she shows a work she is carrying on in order to generalize Leinert-Mann model to the Metis case (out of the ecliptic orbit plus varying distance from the Sun).
PL comments:
Koutchmy-Lamy model is not empirical, is only observations based. On the other hand, the Mann one is an actual model but is based on far too many assumptions. We shall pursue a minimum number of assumptions. There is a way around, I will talk about that in my presentation: the most reliable method in measuring F-Corona is through polarization, since the assumption of negligible F-corona polarization is good up to 20 Rsun from the Sun. The Grotrian method is valid close to the Sun. I consider the polarization based method and the Grotrian one as complementary.
There is no room for modelling F-corona through Mie scattering, which assumes spherical dust particles. We have plenty of evidences that particles are definitely not spherical.
AB shows a well underway activity on a time correlation method to extract F-Corona from the comparison of pB and total Brightness images.
FL question: which is the time frame you need in order to determine the alpha parameter?
AB: 1 month of observations
LT comment: in the Solar Orbiter (and Metis) case, a constant F-Corona (on time scales up to, say 6-12 months) could become an advantage because you could compare observations taken along different lines of sight (thinking of the three 10-days observing windows during each orbit).
PL comment: we observed a long term variation of the F-corona in our 24 years analysis of LASCO images.
PL shows a method for simulating:
the K-corona on the basis of previous solar cycle data and predictive science information;
The F-corona on the basis of a volume scattering function derived from the inversion of observational data.
MR comment: the problem remains of the stray light separation from the F-corona.
PL: I still consider the pB approach the most reliable and robust in order to separate K and F corona. Even AB method relies on very precise B and pB measurements.
PL asks for Metis first light pB images in order to make a comparison with his simulations.
MR agrees on sharing data when ready.
FL comments: PL simulations can be shared with YDL and AB. YDL can use PL simulations in order to constraint dust properties. AB can use PL data in order to help determining the alpha parameter.
BB shows results from his PhD studies on the magnetic field measurement and extrapolation from total solar eclipse data.
In addition BB introduces a work that he is about to complete and publish on the F-Corona, based on narrowband continuum data. A presentation on such work will be scheduled for the topical team next meeting.
FL encourages activities to be carried on by sub-groups, provided that it is a more practical approach, as far as the updates are periodically shared with the whole team.
The minutes will be circulated among the TT members for eventual integrations and finally published on the website.
Next meeting likely to be scheduled in a couple of months (end of November, 2020).
To be discussed in next meeting:
BB progress in F-Corona investigations
PL results in comparing simulations with actual Metis data.
YDL and AB progresses in integrating PL method with their methods.
AOB to be defined
End of the meeting: 18:30 CEST.
Via Google Meet, room: https://meet.google.com/qsd-xeyy-izg
(People outside INAF will need authorization from people already in the room in order to access: F. Landini will be in the room 10 minutes before the telecon official time).
Agenda:
- Welcome and introduction (F. Landini) 5 min
- Metis status update (M. Romoli) 10 min
- Modelling the F corona through the time correlation of the total and polarized brightness images - An update (A. Burtovoi) 20 min
- Simulations of the K+F corona to prepare the observations and analysis of the PSP and SOLO observations - An update (P. Lamy) 20 min
- A 3D model of the F-Corona (Y De Leo) 20 min
- The color of the F-corona: A new inversion method using multi-wavelength unpolarized brightness observations (B. Boe) 20 min
- Topical team discussion and proposals (All)
A. Burtovoi (ABu), A. Berlicki (ABe), B. Boe (BBo), G. Capobianco (GCa), C. Casini (CCa), V. Da Deppo (VDD), Y. De Leo (YDL), P. Lamy (PLa), F. Landini (FLa), I. Mann (IMa), G. Naletto (GNa), M. Romoli (MRo), S. Shestov (SSh), D. Spadaro (DSp), L. Teriaca (LTe), B. Ying (BYi)
FLa communicates that a virtual Metis Workshop will be held on March 17-18, 2021, in order to define the observation goals for the coming LTP4 of Solar Orbiter. Planning will be then discussed during the SOWG-17 (20-21 April 2021).
Time schedule of the Metis Workshop:
9.30 - 12.30 (CET) Wednesday 17 March
14.30 - 17.30 (CET) Wednesday 17 March
9.30 - 13.00 (CET) Thursday 18 March
Update on Solar Orbiter orbit, Metis design and capabilities, Metis scientific products.
The first CME observed in Ly-a is shown.
The apparent inhomogeneity of the UV channel is addressed as well.
An invitation is made for TT people to express desiderata on useful Metis observation to be performed in Solar Orbiter LTP4. The requests will be taken into account during SWT-28 (24-25 March 2021) and discussed at SOWG-17 (20-21 April 2021).
IMa asks whether in-situ observations are available in correspondence of the observed CME.
MRo answers that in this case we don’t have such data, but when future CME will occur, it will be interesting to correlate remote sensing and in-situ results.
ABu presents an update of his work on his time correlation method to extract F-Corona from the comparison of pB and total Brightness images.
IMa comments: there is the assumption of an F-corona stability over 1 month. Is that always true or are there indication that this is not true?
PLa: From our analysis on C2 data it is not entirely true that over a month F-Corona can be considered stable.
MRo: a comment on uncertainties map (slide 25). There is a hole at 220 deg. That hole has not a higher uncertainty, as I would expect.
ABu: that part is a sort of artefact due to the image correction for the presence of the occulter supporting pylon.
PLa presents extracts from a very recent paper (link to the arXiv version), in which a method to disentangle F-corona from K stable component and stray light is described.
MRo: what kind of data would be judged useful from Metis in order to apply your method?
PLa: Metis is useful (together with PSP) in order to probe the Zodiacal Cloud. By putting all the information together, we can reconstruct the 3D distribution of the Zodiacal Cloud.
IMa: In the measurement of the shape of the F-Corona, the instrument orbit plays a role.
PLa: We have a paper that is not submitted yet, on which we use both C2 and C3 observation. The reference F-corona at 1 AU will cover both C2 and C3 FOVs.
YDL presents an extension of the well known Leinert-Mann model to observation points out of the ecliptic, in order to provide a 3D model of the F-corona.
IMa comments: about the formula you use to build up the VSF, if you are based on the Mie scattering, then you don’t need to include the albedo contribution. In any case I would like to continue discussing about your model out of the meeting.
PLa: First, I don't understand the utility of the Thompson Sphere, that has recently been introduced by the NRL group. Second, if you want we can discuss together about particles characteristics (with Mie scattering you bypass all characteristics). We do have an extension of the old work Lamy&Perrin, that is unpublished.
BBo presents an inversion method based on un-polarized multiwavelength images. It has been described in a paper recently submitted to ApJ (links to the arXiv version and local copy)
PLa: the excess of brightness that you observe can be actually due to stray light. Koutchmy demonstrated some years ago that there is a bright ring around the occulter due to the atmospheric light, which produces stray light inside the instrument.
Moreover, you have a big fluctuation of the signal, the curves should be smoother.
BBo: Each point is a measurement along the LOS with its own uncertainty. With only two minutes of observing time we cannot get to the same precision as space-based telescopes.
FLa shows a table that summarizes all the contributions in one page. FLa will circulate the table by asking for integration and corrections, then the table will be published on this website. In addition, FLa asks that each contributor prepares 2-3 slides to synthetically depict his/her work in order to merge all the slides in a single presentation for the coming Metis Workshop.