HOP list   Monthly Events

HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0103

Long duration sit and stare Coronal Hole Observations

plan term


@ @


 name : Bemporad @  e-mail : bemporad[at]oato.inaf.it

contact person in HINODE team

 name : Culhane @  e-mail : jlc[at]mssl.ucl.ac.uk

 abstract of observational proposal
Interplanetary data acquired over the last 20 years by various spacecrafts (such as Ulysses, Voyager 1 & 2, Helios, etc...) demonstrated the presence of MHD waves propagating from the solar corona through the interplanetary medium, but the origin of these waves is far from being completely understood. It has
been recently demonstrated that SOHO/UVCS data can be used in order to study the power spectrum of coronal hole density fluctuations measured with remothe sensing techniques (Bemporad et al, 2008, ApJ, 677, L137). The power spectra of
the Lyman-alpha line intensity (indicative of plasma density) show in the fast wind two power laws: a f^-1 interval between frequencies of 3.0 x 10^-5 and 1.3 x 10^-4 Hz and a f^-2 interval at frequencies smaller than 3.0 x 10^-5 Hz, with
the f^-1 interval mostly associated to the fast wind than the slow wind. This study have been recently extended, thanks also to the occurrence of the SOHO-Ulysses quadratures, to a comparison between fluctuations of the low coronal density and those measured in situ by Ulysses at 3.7 AU (Bemporad et al. 2008, Proc. of the 37th COSPAR Meeting) and by Helios in the inner Helioshere at 0.3 AU (Telloni et al. 2008, Proc. of the AGU Fall Meeting, in
preparation), pointing out also differences between fast and slow wind.

However, the UVCS observations cannot be performed below the heliocentric distance of 1.7 solar radii, making it impossible to understand if these waves originate at the Sun or are produced or possibly enhanced in the corona during the propagation of the solar wind. To this end, in this study we plan to measure for the first time the power spectrum of coronal density fluctuations
over a polar hole in the very low frequency regime (10^-5 Hz < f < 10^-4 Hz). To this end, we need an extended observation period, at least ~ 30 hours of continuous data in order to reach at least a minimum frequency of 10^-5 Hz. In this study the EIS slit will perform a off limb sit & stare observation. In order to minimize the possible effects related to the solar rotation, in this time interval the EIS slit will be centered above the pole at X=0 in the standard heliographyc coordinate system. The line intensity fluctuations could be related also to fluctuations in the stray light coming from the disk; for this reason, the slit field of view will be not placed completely off limb, but disk spectra in the coronal hole will be also acquired with one edge of the slit over 30". In order to reduce the total data volume, the window height will be reduced to 400 pixels, while, in order to perform also a study on the fluctuations of kinetic temperatures from the line profiles, data will be acquired with the 1" slot. It will be in particular interesting to verify if there are correlations between density and kinetic temperature fluctuations and to include in the spectral intervals lines from ions of different elements and ionization stages in order to search for possible dependences from the charge to mass ratio. In this study we are not interested in the high frequencies, because power spectra from UVCS data show that a white noise is dominant at frequencies larger than 10^-4 Hz (hence for exposure times larger than 10^4 s),
hence an exposure time of 500s will be sufficient for our purposes.

These observations will be conducted simultaneously with UVCS observations above the Pole, in order to compare the density fluctuations power spectra of the fast wind at different altitudes.

 request to SOT

 request to XRT

 request to EIS
Study 000457:
ACRONYMS: ab_ch_offlimb_sands
* No Data Compression is selected. SWITCH to DPCM*

This study will focus on the determination of non-thermal velocities of different ions off-limb above a polar coronal hole. In a previous campaign (HOP NUMBER: 103, EIS STUDY: 340) we already performed with Hinode/EIS a long-duration sit & stare observation, allowing us to measure the non-thermal velocity of the FeXII ions up to ~0.4 solar radii off-limb.

The target of this second study will be:

- to make a second attempt to distinguish between plume and inter-plume regions,
dragged by solar rotation in the EIS field of view;

- to include more lines covering different ionization stages, in particular of Fe element, in order to study non-thermal velocities of different ions and different charge-to-mass ratios.

 other participating instruments
SOHO/UVCS by Bemporad + Kohl

This study will be also performed in coordination with the SOHO/UVCS spectrometer, which will acquire EUV spectra at 0.7 solar radii above the limb, in order to compare EIS non-thermal velocities with those measured at higher altitude by UVCS.

target: polar coronal hole (off-limb)
slit/slot: 1"
raster: sit and stare
FOV: 1" X 512"
center: X=0", Y=-1162" (off limb)
exposure time: 500s
# of exposures: 155
Compression: 250 Mbits (****switch to DPCM****)
raster duration: 22h 41m 19s


South polar coronal hole, observed off limb at central meridian (slit center: X=0", Y=-1162").


Run SNS study (ab_ch_offlimb_sands.def).


Please run the study CONTINUOUSLY, even through the SSAs.

name: Dr. Alessandro Bemporad
institute: INAF-Turin Astronomical Observatory
email: bemporad@oato.inaf.it
phone: +39 011 8101 954
fax: +39 011 8101 930

HOP list   Monthly Events