HOP 0422

HINODE Operation Plan (HOP)

accepted on

22-jul-2021

HOP No.

HOP title

HOP 0422

Joint observations of the flare atmosphere

plan term

2021/07/26-2021/07/30
2021/08/02-2021/08/06
2022/05/02-2022/05/06
2022/05/09-2022/05/11

proposer

name :

Rivas, Kasparova, Jurcak, Svanda, Zemanova, Berlicki, Heinzel, Gonzalez, Mravcova

e-mail :

marta.garcia.rivas[at]asu.cas.cz, jana.kasparova[at]asu.cas.cz, jan.jurcak[at]asu.cas.cz, michal[at]astronomie.cz, alena.zemanova[at]asu.cas.cz, berlicki[at]astro.uni.wroc.pl, pheinzel[at]asu.cas.cz, nbello[at]leibniz-kis.de, lucka3[at]gmail.com

contact person in HINODE team

name :

Savage, Watanabe, De Pontieu

e-mail :

sabrina.savage[at]nasa.gov, watanabe.tetsuya[at]nao.ac.jp, bdp[at]lmsal.com

abstract of observational proposal

Main Objective: To observe the atmospheric response to flare heating and support allocated observing time at GREGOR (Tenerife, Spain)

Scientific Justification: White light flares (WLF) are flares with emissions visible at the optical continuum, and also UV enhancements in some cases. Various mechanisms have been proposed to explain the continuum enhancement. Moreover, each mechanism may dominate at different atmospheric layers and, therefore, specific observations are needed to disentangle the contributions. The presence of hydrogen Paschen continuum, originating at the chromosphere, has been observed in off-limb flare observations from HMI/SDO (Heinzel et al. 2017). The presence of the hydrogen Balmer continuum has been observed in on-disc flares observations from IRIS (Heinzel & Kleint 2014; Kleint et al. 2016; Kowalski et al. 2017; Joshi & Schmieder 2021). Additionally, WLF observations from SP/Hinode showed that the optical continuum enhancement is probably not caused by the temperature increase at the formation height of the photospheric continuum, but instead by a photospheric heating down to log τ ~ 0.5, which results in emission profiles of the Fe I lines (Jurcak et al. 2018). They estimated that the major contribution to the increase of the continuum intensity is originating in the heated chromosphere.
With this proposal, we aim to do a follow up study of Jurcak et al. (2018) and Kleint et al. (2017), that is, the study of the stratification of the flare atmosphere by means of space- and ground-based instruments with as high temporal cadence as possible to properly constrain the plasma state of the flaring atmosphere. Meanwhile, we aim to run a complementary study of the temporal evolution of the umbra-penumbra boundary with respect to the properties of the magnetic field.

Spectropolarimetric observations of SP/Hinode will allow us to study the photospheric vector magnetic field within the whole observed sunspot, complementing the smaller FOV of the photospheric and chromospheric IFU-GRIS/GREGOR observations.

IRIS NUV spectra will allow us to study the Balmer continuum emission and line emissions during flares. Slit-jaw images at Mg II wing (2830 A) will complement the images provided by GREGOR (Hα, Ca II h, and blue continuum at 450 nm), thus extending information of the chromospheric emission. The observed emission in hydrogen, Ca II and Mg II lines and continuum will be compared with non-LTE RHD models constructed specifically for the observed flare (e.g. using FLARIX code, Kasparova et al. 2019; Heinzel et al. 2017). If Fermi or STIX/Solar Orbiter data are available, they will be used to constrain the flare heating input.

XRT will provide information about temperature and emission measures of hot flaring loops, allowing us to track the atmosphere response and structure above chromospheric heights.

request to SOT

SOT-SP is required. Normal mode map (0.16 arcsec/pixel, 4.8sec integration, 6 cycles) with a FoV of 82 x 82 arcsec and a temporal cadence of ~43min. 290 Mbits per map, and as many maps as the available telemetry allows.

If it was possible to change the observing mode if XRT detected a flare, then we would require to change to fast mode map (0.32 arcsec/pixel, 3.2sec integration) with a FoV of 82 x 82 arcsec and a temporal cadence of ~15min.

request to XRT

We request the flare program with a medium restrictive setting of the automatic exposure control.

- Normal mode program: Al-poly and Be-thin, 256x256 arcsec, 30 second cadence, with Be-thin and Med-Be in the pre-flare buffer at a 2s cadence, AEC 1

- Flare program: Be-thin and Med-Be, 256x256, 2 sec cadence for the
first 5 minutes of the flare, 20 s thereafter.

Note that it is acceptable to decrease the cadence of normal mode if needed due to other scheduled observations.

request to EIS

None

other participating instruments

IRIS requests:
This proposal has already been discussed with the IRIS team and agreed to be run from August 2 to August 6 if any Active Region is on the solar disc. The position of the IRIS slit is preferred to be positioned perpendicularly to the neutral line or crossing it.

We require a medium datarate OBSID:
3884855853 | Large sit-and-stare 0.3x120 1s Mg II w Deep x 2 Spatial x 2, Spectral | 3.31 | 4.66 | 0.96 | 3.2+/-0.0 | 3.2+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0 | 3.2+/-0.0

Only in case there is any problem with the telemetry, the size of the slit can be reduced to have a low datarate observing program:

3884855852 | Medium sit-and-stare 0.3x60 1s Mg II w Deep x 2 Spatial x 2, Spectral | 3.31 | 2.17 | 0.45 | 3.2+/-0.0 | 3.2+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0 | 3.2+/-0.0

Ground-based co-observations with GREGOR (GRIS, HiFI and M-lite Imagers) in Tenerife, Spain.
Complementary co-observations with the Flare Intensity Continuum Ultrawide Spectrograph (FICUS) and the Horizontal Sonnen Forschungs Anlage (HSFA2) at the Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic, and with the RT-7.5 solar radio telescope at the Bauman Moscow State Technical University, Russia.

remarks

Dates: The GREGOR observing campaign will run from Monday, 26 of July to Friday, 30 of July and from Monday, 2 of August to Friday, 6 of August. Considering that we cannot predict when the ground observing conditions will be ideal, we would like Hinode and IRIS to observe as many days as possible within those dates.

Time window: Observations at the GREGOR telescope are expected to run from 07:30 UT to 13:00 UT. Short interruptions are allowed. In case of overlapping proposals, we prefer to observe during the earliest hours.

Target(s) of interest: The target is a TOO. We aim to observe sunspot umbrae. If there were more than one active region on the solar disc, we would aim at the one with the highest probability of flare occurrence and closest to the disc centre.

Previous HOPs:
HOP 384 and IHOP 405. Unfortunately, the bad observing conditions in the ground-based observatories did not allow us to publish anything.