Many important questions related to Ellerman Bombs (EBs) morphology, dynamics and physical properties remain open. How is the emission in the H alpha line related to UV emission, how do EBs appear in UV and EUV spectral lines, what plasma motions will be derived in these lines, are the footpoint of chromospheric anemone jets associated with Ellerman bombs? Findings on these questions will have important implications for the modelling of EBs. We wish to conduct a programme involving IBIS and ROSA at Sac Peak, coupled with magnetic field data from HMI/SDO, high cadence chromospheric and coronal images from AIA/SDO, plus SOT/Hinode Ca H observations and spectral data with EIS/Hinode. The EBs can be identified via the IBIS H alpha line profile data, while the sufficiently high cadence ROSA and HMI/SDO data will give us information on the movement of the magnetic fragments.
In addition, we would like address the question whether EBs can be found in the quiet Sun. To our knowledge this has not be confirmed so far. Magnetic flux is constantly emerging on the solar surface and although weaker as compared with a plage area, it could trigger events like EBs but on a smaller scale. Presently, SOT/Hinode and HMI/SDO are able to detect magnetic flux better than any instrument so far. That
will give us a great opportunity to search for the relation of quiet Sun magnetic flux emergence with small-scale brightenings and small-scale jets (spicules,macro-spicules, micro-jets etc.). Recently, Sterling et al. (2010, 714, L1) reported on transient brightenings in the SOT Ca II H images associated with spicules occurrence. They found that small-scale jets (rise velocity of 100 km/s) occurred when these brightenings appeared to collide and subsequently disappear. The rise velocity leads one to assume a magnetic reconnection source in the brightening driven by magnetic flux emergence.
Observing programme (Ground)
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We propose to use the DST equipped with ROSA & IBIS for 10 days in mid-late November 2010. With IBIS, we plan to monitor in H alpha. Based on our previous run, we can obtain a 17-pt scan with a cadence of 8 sec (30 ms exposure). With ROSA, we will image in the blue continuum at 3500A and 4170A, the G-band and Ca II K core. With the remaining two ROSA cameras, we will use the tunable UBF filter, positioned in the blue wing of the magnetically sensitive Fe I 6302A line to obtain Stokes V line-of-sight magnetic field information. Once ROSA images have been processed and reconstructed, a cadence of 1~s should be achieved (Jess et al. 2010, Sol Phys 261, 363).
Observing programme (Space)
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With EIS on Hinode we will observe several unblended upper transition region/coronal lines while SOT will observe in Ca II H. We will use existing observing sequences run by ourselves over the past few years. We would like also to run newly developed EIS studies suitable for evaluating the response of AIA/SDO images during transients (including microflares, flares, surges etcs) in the quiet Sun and active regions.
On SDO, we will get AIA images in several wave-bands with a cadence of 12~sec. Magnetogram data will be provided by HMI with a high cadence potential. |
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