STUDY OF H-ALPHA JETS ON THE QUIET SUN

High-speed jets of solar quiet regions have been observed at Big Bear Solar Observatory in H alpha - 1.0 Angstrom and compared with high-res olution magnetograms. Over the whole Sun, the birthrate of the H alpha - 1.0 Angstrom jets is about 19 +/- 3 events s(-1), which is much low er than the birthrate of spicules. The average lifetime of these jets is 2 +/- 1 min. H alpha - 1.0 Angstrom jets are very different from sp icules, in the sense of birthrate, lifetime, and shape. Jets tend to r ecur in the same sites, always located in boundaries of supergranules. Under the best observing conditions, we found that 80% of the major j et sites are associated with converging magnetic dipoles - mainly the sites where intranetwork elements are canceling with opposite polarity network elements. In order to establish a possible relationship betwe en the disk H alpha jets and limb macrospicules, we have also obtained time sequences of H alpha center-line images at the limb. These image s are enhanced by median filtering so that jet structures over the lim b are easily studied. We found that these limb H alpha jets (above the spicule forest) repeatedly occur in the same sites, which is the prop erty shared by the disk H alpha - 1.0 Angstrom jets. However, their me an lifetime is 10 min, substantially longer than that of disk jets. Co mparison with simultaneous SOHO/EIT He II 304 Angstrom images shows th at every He II 304 Angstrom jet over the limb coincides with an Her je t, although He II 304 A jets extend much farther out. Some H alpha jet s do not have associated He jets, probably due to the difference in im age resolutions. H alpha spectra of selected jets are analyzed, and we found that jets are not simply blue-shifted; instead, the line profil es are broadened with significantly larger broadening on the blue side . Two-component fitting finds that the velocity of the blue-shifted co mponent (an optically-thin component) is around 20 to 40 km s(-1).