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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0197

The Formation and Evolution of Filament Channels  and their Filaments

plan term


@ @


 name : Martin, Panasenco, Pevtsov, Karachik, Engvold, Lin, Srivastava @  e-mail : sara[at]helioresearch.org

contact person in HINODE team

 name : Berger @  e-mail : berger[at]lmsal.com

 abstract of observational proposal
The scientific objectives of the HOP are to test the Litvinenko model (1999) and Litvinenko et al model (2007) of filament formation in collaboration with ground-based observations on the IBIS instrument at the Dunn Solar Telescope and other ground-based observatories.  According to the more recent Litvinenko et al model (2007), magnetic flux at the sites of cancelling magnetic fields, at discrete locations along the main polarity boundary in filament channels, is reconfigured by magnetic pile-up reconnection near the photosphere; the line-of-sight component is transformed by this type of reconnection into the horizontal component directed along the polarity reversal boundary.  Concurrently magnetic field is brought into the low corona and mass is ejected along the new, rising horizontal component and forms a visible filament if the cancellation and mass ejection rates are sufficiently high. This theoretical model is regarded by our observing team as applicable to both the formation of filament channels and to the formation of filaments after a filament channel has reached maximum development.  This HOP includes testing the Litvinenko model under both conditions.

In addition to testing this primary concept, we seek to additionally verify the conditions of cancelling fields expected from the theory:  The conditions are that the rate of cancellation depends on (1) the magnitude of the magnetic flux, and (2) its rate of inflow to the reconnection site at the cancelling field sites.  According to Litvinenko (2010), the rates of inflow are expected to be variable.  It is anticipated that the rates of cancellation could depend on the locations of the cancelling fields relative to the boundaries and vertices of the large-scale convection cells and whether the cancelling sites are in active regions (mesogranules), on the borders of active regions or external to active regions (supergranules).  

The observational goal of this HOP is to observe the magnetic fields of filament channels as early in their development as feasible and as completely during their evolution as compatible with circumstances on the Sun when the HOP is run.  The HOP is applicable to the entire spectrum of filament channels from those in active regions with high photospheric magnetic field density to those on the quiet Sun with low magnetic field density.  For the clear detection of both their line-of-sight and plane-of-sky magnetic field components, the observing targets usually will be limited to 900 arc seconds from the Sunfs central meridian.  During the first requested interval for this HOP and whenever Hinode is in its eclipse season, concurrent H observations will be sought at collaborating observatories rather than from Hinode.

In active regions, the initial channel formation and filament formation can be nearly concurrent while in intermediate or quiescent filament channels, initial filament formation follows channel formation (reviews by Gaizauskas 1998; Martin 1998).  After an initial eruptive solar event associated with a given filament channel, new filaments very frequently form within the same filament channel.  For this reason, the HOP is applicable to observing filament channels during and after eruptive solar events. This choice of observing target will be implemented (or not) at the discretion of the participants who choose the observing targets.  

During a single observing run, it is usually not possible to observe the complete evolution of both a filament channel and filament in the same channel until the filament erupts with an associated CME and flare.  Therefore, this HOP is expected to be a choice for future observing intervals in addition to the first one.  

The highest probability for observing the majority of the stages of filament channel and filament formation within the same channel is by observing the area within and around small new active regions where magnetic flux of opposite polarity fields are either driven or drift together and then begin to cancel.  For this HOP, the first priority in target selection is where the project participants anticipate the formation of a filament channel.  However, such circumstances might not exist when target selection is necessary.  Therefore, the second priority is to observe a filament channel that is already forming or has formed but does not yet contain a filament.  The third priority is observing the filament channel and a filament that has already formed.   The primary observations sought with Hinode are both longitudinal and vector magnetograms of the photosphere where cancelling magnetic fields are observed. The target areas and coordinates for observation will be centered on or close to polarity reversal boundaries (also known as polarity inversion lines) including the adjacent areas out to and including the base of the adjacent magnetic fields which are expected to be at the feet of the coronal loops overlying the filament channel (or anticipated filament channel).  

The objectives for evolutionary data on the same filament channel will be weighed against new target selection according to the priorities above as offered by current solar activity.   An objective is to anticipate target changes two days in advance of observations in keeping with the operations of Hinode.

The observing hours during the first request for this HOP are 14:00-02:00  UT in coordination with a scheduled observations by our observing team on the IBIS instrument on the Dunn Solar Telescope and simultaneous observations on the NST at Big Bear Solar Observatory and Helio Research.  It is acknowledged that the assigned observing hours might be reduced at the end of the requested interval if the data exceeds the amount that can be telemetered daily to the ground.

This HOP contains both new objectives and observing objectives that are similar and compatible with HOP 0139 and HOP 0166.  HOP 0166 is scheduled for the latter 8 days of the 9 days for this new HOP but during different observing hours.  The cadence for this HOP is higher than that of HOP 0166.


Gaizauskas, V. Filament Channels: Essential Ingredients for Filament Formation (Review),  in New Perspective on Solar Prominences, IAU Colloquium 167, ASP Conf. Series, v. 150, 257-264 (1998)

Litvinenko, Y. E., Photospheric Magnetic Reconnection and Canceling Magnetic Features
on the Sun, Astrophys. J. 515, p. 435 (1999)

Litvinenko, Y., Chae, J., and Park, S.-Y.: Flux Pile-up Magnetic Reconnection in the Solar Photosphere, Astrophys. J. 662, p. 1302-1308 (2007)

Litvinenko, Y. E.,
Evolution of the Axial Magnetic Field in Solar Filament Channels,
2010, Astrophys. J., 720, 948-952

Martin, S.F. Conditions for the Formation and Maintenance of Filaments (Invited Review), Solar Phys., 182, p. 107-137 (1998)

 request to SOT
Spectro-Polarimeter (SP):

FOV depends on the location and length of polarity reversal boundary (polarity inversion line).  The duration is given as 10 hours but less is acknowledged as limited by telemetry

High resolution vector magnetic field measurements in Fe I 630.2 nm   Single-sided, fast map (cycle 2) FOV= 80h x 80h or 40h x 120h, sum=2x2, cadence=repeat,

Narrowband Filter Instrument (NFI):

Longitudinal magnetogram/Dopplergram/line center imaging in the Na I D line sequences of the magnetic fields in filament channels,  80hx 80h or 40h x 120h, fastest cadence

Broadband Filter Instrument (BFI):

Ca - FOV=80hx80h or 40h x 120h, sum=2x2, cadence=4 minute, Q=65
18 Mbits/hour

G-band - FOV=80hx80h or 40h x 120h, sum=2x2, cadence=1 minute, Q=65
(A 1-min cadence is necessary for the calculation of the surface flows.)
75 Mbits/hour

Na IVDG - FOV=80hx80h or 40h x 120h, sum=2x2, cadence=4 minutes, Q1=65, Q2=75
24 Mbits/hour

H – None during Hinode eclipse season.
Otherwise, line center imaging sequences from the NFI: 164x164h, 30 sec. cadence

 request to XRT
Supporting observations from XRT and EIS similar to that used by HOP 0150 are included in case transition region jets,  X-ray bright points (XBPs), or flares occur in the observed filament channels.  

 request to EIS
Supporting observations from XRT and EIS similar to that used by HOP 0150 are included in case transition region jets,  X-ray bright points (XBPs), or flares occur in the observed filament channels.  

 other participating instruments
IBIS at the Dunn Solar Telescope (DST):
E Spectro-polarimetry in the photospheric Fe I line at 617.3 nm along with ECa I H line or G-band.

E Spectro-polarimetry in Ha on the NST at Big Bear Solar Observatory.  Collaborators:  Y. Yurchyshyn and Wenda Cao

SOLIS at Kitt Peak
Echromospheric magnetograms at 854.2 nm in area scan mode.  

Martin Solar Telescope at Helio Research
E25 cm aperture with LiNbO3 tunable filter operated at H for Doppler imaging from 5 to 11 positions across the H line.
E For medium resolution context data on 9 x 9 arc min. FOV.

These proposed Hinode observations are intended to significantly augment  an observing run already scheduled on IBIS at the Dunn Solar Telescope from 16-24 July 2011.  15 July is scheduled for set-up time at the DST.  Collaborative observations are also planned at the NST at Big Bear Solar Observatory with collaborators, Y. Yurchyshyn on 16 and 17 July and Wenda Cao from July 18-24 with observing hours from 14-02 UT.  

We have taken note that HOP166 is also already scheduled for observations from 16-24 July 2011, 9-12 UT to coordinate with observations at the VTT.

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