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We consider small-scale jetlike events that might make the solar wind, as has been suggested in recent studies. We show that the events referred to as "coronal jets" and as "jetlets" both fall on a power-law distribution that also includes large-scale eruptions and spicule-sized features; all of the jetlike events could contribute to the solar wind. Based on imaging and magnetic field data, it is plausible that many or most of these events might form by the same mechanism: Magnetic flux cancelation produces small-scale flux ropes, often containing a cool-material minifilament. This minifilament/flux rope erupts and reconnects with adjacent open coronal field, along which "plasma jets" flow and contribute to the solar wind. The erupting flux ropes can contain twist that is transferred to the open field, and these become Alfvénic pulses that form magnetic switchbacks, providing an intrinsic connection between switchbacks and the production of the solar wind. [ABSTRACT FROM AUTHOR]

Solar X-ray jets are imaged by satellite-borne telescopes in space in the ~0.2-2.0-keV range. They are dynamic (with upward velocities of around 200 km [s.sup.-1]), long (about 5 X [10.sup.4] [...], Solar X-ray jets are thought to be made by a burst of reconnection of closed magnetic field at the base of a jet with ambient open field (1,2). In the accepted version of the 'emerging-flux' model, such a reconnection occurs at a plasma current sheet between the open field and the emerging closed field, and also forms a localized X-ray brightening that is usually observed at the edge of the jet's base (1,3). Here we report high-resolution X-ray and extreme-ultraviolet observations of 20 randomly selected X-ray jets that form in coronal holes at the Sun's poles. In each jet, contrary to the emerging-flux model, a miniature version of the filament eruptions that initiate coronal mass ejections (4-7) drives the jet-producing reconnection. The X-ray bright point occurs by reconnection of the 'legs' of the minifilament-carrying erupting closed field, analogous to the formation of solar flares in larger-scale eruptions. Previous observations have found that some jets are driven by base-field eruptions (8-11), but only one such study, of only one jet, provisionally questioned the emerging-flux model (12). Our observations support the view that solar filament eruptions are formed by a fundamental explosive magnetic process that occurs on a vast range of scales, from the biggest mass ejections and flare eruptions down to X-ray jets, and perhaps even down to smaller jets that may power coronal heating (10,13,14). A similar scenario has previously been suggested, but was inferred from different observations and based on a different origin of the erupting minifilament (15).

A challenge in characterizing active region (AR) coronal heating is in separating transient (bursty) loop heating from the diffuse background (steady) heating. We present a method of quantifying coronal heating's bursty and steady components in ARs, applying it to Fe xviii (hot 94) emission of an AR observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The maximum-, minimum-, and average-brightness values for each pixel, over a 24 hr period, yield a maximum-brightness map, a minimum-brightness map, and an average-brightness map of the AR. Running sets of such three maps come from repeating this process for each time step of running windows of 20, 16, 12, 8, 5, 3, 1, and 0.5 hr. From each running window's set of three maps, we obtain the AR's three corresponding luminosity light curves. We find (1) the time-averaged ratio of minimum-brightness-map luminosity to average-brightness-map luminosity increases as the time window decreases, and the time-averaged ratio of maximum-brightness-map luminosity to average-brightness-map luminosity decreases as the window decreases; (2) for the 24 hr window, the minimum-brightness map's luminosity is 5% of the average-brightness map's luminosity, indicating that at most 5% of the AR's hot 94 luminosity is from heating that is steady for 24 hr; (3) this upper limit on the fraction of the hot 94 luminosity from steady heating increases to 33% for the 30 minute running window. This requires that the heating of the 4–8 MK plasma in this AR is mostly in bursts lasting less than 30 minutes: at most a third of the heating is steady for 30 minutes. [ABSTRACT FROM AUTHOR]

We examine the cradle-to-grave magnetic evolution of 10 bipolar ephemeral active regions (BEARs) in solar coronal holes, especially aspects of the magnetic evolution leading to each of 43 obvious microflare events. The data are from the Solar Dynamics Observatory: 211 Ă... coronal EUV images and line-of-sight photospheric magnetograms. We find evidence that (1) each microflare event is a magnetic explosion that results in a miniature flare arcade astride the polarity inversion line (PIL) of the explosive lobe of the BEAR’s anemone magnetic field; (2) relative to the BEAR’s emerged flux-rope Ω loop, the anemone’s explosive lobe can be an inside lobe, an outside lobe, or an inside-and-outside lobe; (3) 5 events are confined explosions, 20 events are mostly confined explosions, and 18 events are blowout explosions, which are miniatures of the magnetic explosions that make coronal mass ejections (CMEs); (4) contrary to the expectation of Moore et al., none of the 18 blowout events explode from inside the BEAR’s Ω loop during the Ω loop’s emergence; and (5) before and during each of the 43 microflare events, there is magnetic flux cancellation at the PIL of the anemone’s explosive lobe. From finding evident flux cancellation at the underlying PIL before and during all 43 microflare eventsâ€"together with BEARs evidently being miniatures of all larger solar bipolar active regionsâ€"we expect that in essentially the same way, flux cancellation in sunspot active regions prepares and triggers the magnetic explosions for many major flares and CMEs. [ABSTRACT FROM AUTHOR]

We analyze the formation mechanism of three homologous broad coronal mass ejections (CMEs) resulting from a series of solar blowout-eruption flares with successively increasing intensities (M2.0, M2.6, and X1.0). The flares originated from NOAA Active Region 12017 during 2014 March 28â€"29 within an interval of ≈24 hr. Coronal magnetic field modeling based on nonlinear force-free field extrapolation helps to identify low-lying closed bipolar loops within the flaring region enclosing magnetic flux ropes. We obtain a double flux rope system under closed bipolar fields for all the events. The sequential eruption of the flux ropes led to homologous flares, each followed by a CME. Each of the three CMEs formed from the eruptions gradually attained a large angular width, after expanding from the compact eruption-source site. We find these eruptions and CMEs to be consistent with the “magnetic-arch-blowout” scenario: each compact-flare blowout eruption was seated in one foot of a far-reaching magnetic arch, exploded up the encasing leg of the arch, and blew out the arch to make a broad CME. [ABSTRACT FROM AUTHOR]

Using EUV images and line-of-sight magnetograms from Solar Dynamics Observatory, we examine eight emerging bipolar magnetic regions (BMRs) in central-disk coronal holes for whether the emerging magnetic arch made any noticeable coronal jets directly, via reconnection with ambient open field as modeled by Yokoyama & Shibata. During emergence, each BMR produced no obvious EUV coronal jet of normal brightness, but each produced one or more faint EUV coronal jets that are discernible in AIA 193 Å images. The spires of these jets are much fainter and usually narrower than for typical EUV jets that have been observed to be produced by minifilament eruptions in quiet regions and coronal holes. For each of 26 faint jets from the eight emerging BMRs, we examine whether the faint spire was evidently made a la Yokoyama & Shibata. We find that (1) 16 of these faint spires evidently originate from sites of converging opposite-polarity magnetic flux and show base brightenings like those in minifilament-eruption-driven coronal jets, (2) the 10 other faint spires maybe were made by a burst of the external-magnetic-arcade-building reconnection of the emerging magnetic arch with the ambient open field, with reconnection directly driven by the arch's emergence, but (3) none were unambiguously made by such emergence-driven reconnection. Thus, for these eight emerging BMRs, the observations indicate that emergence-driven external reconnection of the emerging magnetic arch with ambient open field at most produces a jet spire that is much fainter than in previously reported, much more obvious coronal jets driven by minifilament eruptions. [ABSTRACT FROM AUTHOR]

Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images the full solar disk in several extreme-ultraviolet (EUV) bands that are each sensitive to coronal plasma emissions of one or more specific temperatures. We observe that when isolated active regions (ARs) are on the disk, full-disk images in some of the coronal EUV channels show the outskirts of the AR as a dark moat surrounding the AR. Here we present seven specific examples, selected from time periods when there was only a single AR present on the disk. Visually, we observe the moat to be most prominent in the AIA 171 Å band, which has the most sensitivity to emission from plasma at log10T = 5.8. By examining the 1D line-of-sight emission measure temperature distribution found from six AIA EUV channels, we find the intensity of the moat to be most depressed over the temperature range log10T ≈ 5.7–6.2 for most of the cases. We argue that the dark moat exists because the pressure from the strong magnetic field that splays out from the AR presses down on underlying magnetic loops, flattening those loops—along with the lowest of the AR's own loops over the moat—to a low altitude. Those loops, which would normally emit the bulk of the 171 Å emission, are restricted to heights above the surface that are too low to have 171 Å emitting plasmas sustained in them, according to Antiochos & Noci, while hotter EUV-emitting plasmas are sustained in the overlying higher-altitude long AR-rooted coronal loops. This potentially explains the low-coronal-temperature dark moats surrounding the ARs. [ABSTRACT FROM AUTHOR]

A recent study demonstrated that freedom of convection and strength of magnetic field in the photospheric feet of active-region (AR) coronal loops, together, can engender or quench heating in them. Other studies stress that magnetic flux cancellation at the loop-feet potentially drives heating in loops. We follow 24 hr movies of a bipolar AR, using extreme ultraviolet images from the Atmospheric Imaging Assembly/Solar Dynamics Observatory (SDO) and line-of-sight (LOS) magnetograms from the Helioseismic and Magnetic Imager (HMI)/SDO, to examine magnetic polarities at the feet of 23 of the brightest coronal loops. We derived Fe xviii emission (hot-94) images (using the Warren et al. method) to select the hottest/brightest loops, and confirm their footpoint locations via non-force-free field extrapolations. From 6″ × 6″ boxes centered at each loop foot in LOS magnetograms we find that ∼40% of the loops have both feet in unipolar flux, and ∼60% of the loops have at least one foot in mixed-polarity flux. The loops with both feet unipolar are ∼15% shorter lived on average than the loops having mixed-polarity foot-point flux, but their peak-intensity averages are equal. The presence of mixed-polarity magnetic flux in at least one foot in the majority of the loops suggests that flux cancellation at the footpoints may drive most of the heating. But the absence of mixed-polarity magnetic flux (to the detection limit of HMI) in ∼40% of the loops suggests that flux cancellation may not be necessary to drive heating in coronal loops—magnetoconvection and field strength at both loop feet possibly drive much of the heating, even in the cases where a loop foot presents mixed-polarity magnetic flux. [ABSTRACT FROM AUTHOR]

We investigate the onsets of three consecutive coronal mass ejection (CME) eruptions in 12 hr from a large bipolar active region (AR) observed by the Solar Dynamics Observatory (SDO), the Solar Terrestrial Relations Observatory (STEREO), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and the Geostationary Operational Environmental Satellite (GOES). Evidently, the AR initially had a "triple-decker" configuration: three flux ropes in a vertical stack above the polarity inversion line (PIL). Upon being bumped by a confined eruption of the middle flux rope, the top flux rope erupts to make the first CME and its accompanying AR-spanning flare arcade rooted in a far apart pair of flare ribbons. The second CME is made by eruption of the previously arrested middle flux rope, which blows open the flare arcade of the first CME and produces a flare arcade rooted in a pair of flare ribbons closer to the PIL than those of the first CME. The third CME is made by blowout eruption of the bottom flux rope, which blows open the second flare arcade and makes its own flare arcade and pair of flare ribbons. Flux cancellation observed at the PIL likely triggers the initial confined eruption of the middle flux rope. That confined eruption evidently triggers the first CME eruption. The lid-removal mechanism instigated by the first CME eruption plausibly triggers the second CME eruption. Further lid removal by the second CME eruption plausibly triggers the final CME eruption. [ABSTRACT FROM AUTHOR]

We examine the initiation of 10 coronal jet eruptions in quiet regions on the central disk, thereby avoiding near-limb spicule-forest obscuration of the slow-rise onset of the minifilament eruption. From the Solar Dynamics Observatory/Atmospheric Imaging Assembly 171 Å 12 s cadence movie of each eruption, we (1) find and compare the start times of the minifilament's slow rise, the jet-base bright point, the jet-base-interior brightening, and the jet spire, and (2) measure the minifilament's speed at the start and end of its slow rise. From (a) these data, (b) prior observations showing that each eruption was triggered by magnetic flux cancelation under the minifilament, and (c) the breakout-reconnection current sheet observed in one eruption, we confirm that quiet-region jet-making minifilament eruptions are miniature versions of CME-making filament eruptions, and surmise that in most quiet-region jets: (1) the eruption starts before runaway reconnection starts, (2) runaway reconnection does not start until the slow-rise speed is at least ∼1 km s−1, and (3) at and before eruption onset, there is no current sheet of appreciable extent. We therefore expect that (i) many CME-making filament eruptions are triggered by flux cancelation under the filament, (ii) emerging bipoles seldom, if ever, directly drive jet production because the emergence is seldom, if ever, fast enough, and (iii) at a separatrix or quasi-separatrix in any astrophysical setting of a magnetic field in low-beta plasma, a current sheet of appreciable extent can be built only dynamically by a magnetohydrodynamic convulsion of the field, not by quasi-static gradual converging of the field. [ABSTRACT FROM AUTHOR]

We examine the three-dimensional magnetic structure and dynamics of a solar EUV-macrospicule jet that occurred on 2011 February 27 in an on-disk coronal hole. The observations are from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) and the SDO Helioseismic and Magnetic Imager (HMI). The observations reveal that in this event, closed-field-carrying cool absorbing plasma, as in an erupting mini-filament, erupted and opened, forming a blowout jet. Contrary to some jet models, there was no substantial recently emerged, closed, bipolar-magnetic field in the base of the jet. Instead, over several hours, flux convergence and cancellation at the polarity inversion line inside an evolved arcade in the base apparently destabilized the entire arcade, including its cool-plasma-carrying core field, to undergo a blowout eruption in the manner of many standard-sized, arcade-blowout eruptions that produce a flare and coronal mass ejection. Internal reconnection made bright “flare” loops over the polarity inversion line inside the blowing-out arcade field, and external reconnection of the blowing-out arcade field with an ambient open field made longer and dimmer EUV loops on the outside of the blowing-out arcade. That the loops made by the external reconnection were much larger than the loops made by the internal reconnection makes this event a new variety of blowout jet, a variety not recognized in previous observations and models of blowout jets. [ABSTRACT FROM AUTHOR]

We present results from a study of 54 polar X-ray jets that were observed in coronal X-ray movies from the X-ray Telescope on Hinode and had simultaneous coverage in movies of the cooler transition region (T ∼ 105 K) taken in the He II 304Å band of the Atmospheric Imaging Assembly (AIA) on Solar Dynamics Observatory. These dual observations verify the standard-jet/blowout-jet dichotomy of polar X-ray jets previously found primarily from XRT movies alone. In accord with models of blowout jets and standard jets, the AIA 304Å movies show a cool(T ∼ 105 K) component in nearly all blowout X-ray jets and in a small minority of standard X-ray jets, obvious lateral expansion in blowout X-ray jets but none in standard X-ray jets, and obvious axial rotation in both blowout X-ray jets and standard X-ray jets. In our sample, the number of turns of axial rotation in the cool-component standard X-ray jets is typical of that in the blowout X-ray jets, suggesting that the closed bipolar magnetic field in the jet base has substantial twist not only in all blowout X-ray jets but also in many standard X-ray jets. We pointout that our results for the dichotomy, lateral expansion, and axial rotation of X-ray jets add credence to published speculation that type-II spicules areminiature analogs of X-ray jets, are generated by granule-size emerging bipoles, and thereby carry enough energy to power the corona and solar wind. [ABSTRACT FROM AUTHOR]

It has been found previously, by measuring from active-region magnetograms a proxy of the free energy in the active region's magnetic field, (1) that there is a sharp upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region's magnetic flux content, and (2) that most active regions are near this limit when their field explodes in a coronal mass ejection/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy-limit line in (flux content, free- energy proxy) phase space. Here, we present evidence that specifies the underlying magnetic condition that gives rise to the free-energy limit and the accompanying main sequence of explosive active regions. Using a suitable free-energy proxy measured from vector magnetograms of 44 active regions, we find evidence that (1) in active regions at and near their free-energy limit, the ratio of magnetic-shear free energy to the non-free magnetic energy the potential field would have is of the order of one in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free-energy limit. Evidently, most active regions in which this core-field energy ratio is much less than one cannot be triggered to explode; as this ratio approaches one, most active regions become capable of exploding; and when this ratio is one, most active regions are compelled to explode. [ABSTRACT FROM AUTHOR]

Two GOES sub-C-class precursor eruptions occurred within ~10 hr prior to and from the same active region as the 2006 December 13 X4.3-class flare. Each eruption generated a coronal mass ejection (CME) with center laterally far offset (≳°) from the co-produced bright flare. Explaining such CME-to-flare lateral offsets in terms of the standard model for solar eruptions has been controversial. Using Hinode/X-Ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) data, and Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) and Michelson Doppler Imager (MDI) data, we find or infer the following. (1) The first precursor was a "magnetic-arch-blowout" event, where an initial standard-model eruption of the active region's core field blew out a lobe on one side of the active region's field. (2) The second precursor began similarly, but the core-field eruption stalled in the side-lobe field, with the side-lobe field erupting ~ 1 hr later to make the CME either by finally being blown out or by destabilizing and undergoing a standard-model eruption. (3) The third eruption, the X-flare event, blew out side lobes on both sides of the active region and clearly displayed characteristics of the standard model. (4) The two precursors were offset due in part to the CME originating from a side-lobe coronal arcade that was offset from the active region's core. The main eruption (and to some extent probably the precursor eruptions) was offset primarily because it pushed against the field of the large sunspot as it escaped outward. (5) All three CMEs were plausibly produced by a suitable version of the standard model. [ABSTRACT FROM AUTHOR]

Discusses the potential of breath freshener strips (BFS) to interfere with the accuracy of breath alcohol test. Examination of varieties of BFS with the infrared-based BAC DataMaster; Results of the use of the Alco-Sensor system; Proposal for proper pre-test observation and deprivation period before the breath alcohol testing.

We analyze data from SDO (AIA, HMI), Hinode (SOT, XRT, EIS), and STEREO (EUVI) of a solar eruption sequence of 2011 June 1 near 16:00 UT, with an emphasis on the early evolution toward eruption. Ultimately, the sequence consisted of three emission bursts and two filament ejections. SDO/AIA 304 Å images show absorbing-material strands initially in close proximity which over ∼20 minutes form a twisted structure, presumably a flux rope with ∼1029 erg of free energy that triggers the resulting evolution. A jump in the filament/flux rope's displacement (average velocity ∼20 km s–1) and the first burst of emission accompanies the flux-rope formation. After ∼20 more minutes, the flux rope/filament kinks and writhes, followed by a semi-steady state where the flux rope/filament rises at (∼5 km s–1) for ∼10 minutes. Then the writhed flux rope/filament again becomes MHD unstable and violently erupts, along with rapid (50 km s–1) ejection of the filament and the second burst of emission. That ejection removed a field that had been restraining a second filament, which subsequently erupts as the second filament ejection accompanied by the third (final) burst of emission. Magnetograms from SDO/HMI and Hinode/SOT, and other data, reveal several possible causes for initiating the flux-rope-building reconnection, but we are not able to say which is dominant. Our observations are consistent with magnetic reconnection initiating the first burst and the flux-rope formation, with MHD processes initiating the further dynamics. Both filament ejections are consistent with the standard model for solar eruptions. [ABSTRACT FROM AUTHOR]

From a large database of (1) 40,000 SOHO/MDI line-of-sight magnetograms covering the passage of 1300 sunspot active regions across the 30° radius central disk of the Sun, (2) a proxy of each active region's free magnetic energy measured from each of the active region's central-disk-passage magnetograms, and (3) each active region's full-disk-passage history of production of major flares and fast coronal mass ejections (CMEs), we find new statistical evidence that (1) there are aspects of an active region's magnetic field other than the free energy that are strong determinants of the active region's productivity of major flares and fast CMEs in the coming few days; (2) an active region's recent productivity of major flares, in addition to reflecting the amount of free energy in the active region, also reflects these other determinants of coming productivity of major eruptions; and (3) consequently, the knowledge of whether an active region has recently had a major flare, used in combination with the active region's free-energy proxy measured from a magnetogram, can greatly alter the forecast chance that the active region will have a major eruption in the next few days after the time of the magnetogram. The active-region magnetic conditions that, in addition to the free energy, are reflected by recent major flaring are presumably the complexity and evolution of the field. [ABSTRACT FROM AUTHOR]