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Cirtain, Jonathan W.

Publications and source records attributed to Cirtain, Jonathan W..

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Chromospheric LAyer SpectroPolarimeter (CLASP2)

The sounding rocket Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) was launched on September 3rd, 2015, and successfully detected (with a polarization accuracy of 0.1 %) the linear polarization signals (Stokes Q and U) that scattering processes were predicted to produce in the hydrogen Lyman-alpha line (Ly; 121.567 nm). Via the Hanle effect, this unique data set may provide novel information about the magnetic structure and energetics in the upper solar chromosphere. The CLASP instrument was safely recovered without any damage and we have recently proposed to dedicate its second ight to observe the four Stokes profiles in the spectral region of the Mg II h and k lines around 280 nm; in these lines the polarization signals result from scattering processes and the Hanle and Zeeman effects. Here we describe the modifications needed to develop this new instrument called the "Chromospheric LAyer SpectroPolarimeter" (CLASP2).

CLASP↗
NASA NTRS2014

Testing the Solar Probe Cup, an Instrument Designed to Touch the Sun

Solar Probe Plus will be the first, fastest, and closest mission to the sun, providing the first direct sampling of the sub-Alfvenic corona. The Solar Probe Cup (SPC) is a unique re-imagining of the traditional Faraday Cup design and materials for immersion in this high temperature environment. Sending an instrument of this type into a never-seen particle environment requires extensive characterization prior to launch to establish sufficient measurement accuracy and instrument response. To reach this end, a slew of tests for allowing SPC to see ranges of appropriate ions and electrons, as well as a facility that reproduces solar photon spectra and fluxes for this mission. Having already tested the SPC at flight like temperatures with no significant modification of the noise floor, we recently completed a round of particle testing to see if the deviations in Faraday Cup design fundamentally change the operation of the instrument. Results and implications from these tests will be presented, as well as performance comparisons to cousin instruments such as those on the WIND spacecraft.

Whittlesey, Phyllis L.↗
NASA NTRS2014

Deciphering Solar Magnetic Activity. I. On the Relationship Between the Sunspot Cycle and the Evolution of Small Magnetic Features

Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22 yr. The principal variation of sunspots, an ~11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability.

Sun: interior↗
NASA NTRS2012

Loop Evolution Observed with AIA and Hi-C

In the past decade, the evolution of EUV loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this presentation we discuss the first results of loop analysis comparing AIA and Hi-C data. In the past decade, the evolution of EUV loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this presentation we discuss the first results of loop analysis comparing AIA and Hi-C data.

Mulu-Moore, Fana↗
NASA NTRS2011

New Results From Hinode: A Systems Science Approach To Heliophysics

Recent results from the analysis of Hinode data have been used to determine the origins of the fast and slow solar wind, possible heating sources for the solar corona, and onset locations for CMEs and polar x-ray jets. Using this information, and data collected by other observatories, major advances in the understanding of Heliophysics are now possible. These Hinode observations, and the techniques for analysis of the Hinode data will be discussed."

Cirtain, Jonathan W.↗
NASA NTRS2010

Polar Coronal Hole Ephemeral Regions, the Fast Solar Wind and the Global Magnetic Dynamo

The X-Ray Telescope aboard Hinode has been regularly observing both the north and south solar polar coronal holes from November 2006 through March 2009. We use the observations of emerged flux regions within the coronal hole as evidenced by small x-ray bright points to study the physical properties of these regions. The width of the emerged flux region loop footpoints, the duration of the x-ray emission lifetime for the emerged flux region, the latitude of formation and whether an x-ray or EUV jet was observed were all recorded. In the present work we detail these observations and show a dependence on the width of the emerged flux region (bright point) to the number of x-ray jets observed. The distribution of base width is then related to a power law for number of emerged flux regions as a function of base width.

Cirtain, Jonathan W.↗
NASA NTRS2010

Blowout Jets: Hinode X-Ray Jets that Don't Fit the Standard Model

Nearly half of all H-alpha macrospicules in polar coronal holes appear to be miniature filament eruptions. This suggests that there is a large class of X-ray jets in which the jet-base magnetic arcade undergoes a blowout eruption as in a CME, instead of remaining static as in most solar X-ray jets, the standard jets that fit the model advocated by Shibata. Along with a cartoon depicting the standard model, we present a cartoon depicting the signatures expected of blowout jets in coronal X-ray images. From Hinode/XRT movies and STEREO/EUVI snapshots in polar coronal holes, we present examples of (1) X-ray jets that fit the standard model, and (2) X-ray jets that do not fit the standard model but do have features appropriate for blowout jets. These features are (1) a flare arcade inside the jet-base arcade in addition to the small flare arcade (bright point) outside that standard jets have, (2) a filament of cool (T is approximately 80,000K) plasma that erupts from the core of the jetbase arcade, and (3) an extra jet strand that should not be made by the reconnection for standard jets but could be made by reconnection between the ambient unipolar open field and the opposite-polarity leg of the filament-carrying flux-rope core field of the erupting jet-base arcade. We therefore infer that these non-standard jets are blowout jets, jets made by miniature versions of the sheared-core-arcade eruptions that make CMEs

Moore, Ronald L.↗
NASA NTRS2009

Blowout Jets: Evidence from Hinode/XRT for X-Ray Jets Made by Blowout Eruption of the Emerging Bipole

Yamauchi et al (2004, ApJ, 605, 511) found that there are two structurally and dynamically distinct types of H macrospicules in polar coronal holes: single-column jet macrospicules and erupting-loop macrospicules. The structure and motion of the single-column jet macrospicules fit the standard Shibata reconnection picture for solar X-ray jets (Shibata et al 1992, PASJ, 44, L173). The form and motion of the erupting-loop macrospicules is reminiscent of the ejective eruption of the sheared-core-field flux rope in the filament-eruption birth of a bubble-type coronal mass ejection (CME). That roughly half of all polar H macrospicules were observed to be erupting-loop macrospicules suggests that there should be a corresponding large class of X-ray jets in which the emerging bipole at the base of the jet undergoes a blowout eruption as in a bubble-type CME, instead of staying closed as in the standard picture for X-ray jets. Along with a cartoon of the standard picture, we present a cartoon depicting the signatures to be expected of a blowout jet in high-resolution coronal X-ray movies such as from Hinode/XRT. From Hinode/XRT movies in polar coronal holes, we show: (1) examples of X-ray jets that fit the standard picture very well, and (2) other examples that do not fit the standard picture but do show signatures appropriate for blowout jets. These signatures are (1) a flare arcade inside the emerging bipole in addition to the flare arcade produced between the emerging bipole and the ambient high-reaching unipolar field by reconnection of these two fields as in the standard picture, and (2) in addition to the jet prong expected from the standard reconnection, a second jet prong or strand, one that could not be produced by the standard reconnection but could be produced by reconnection between the ambient unipolar field and one leg of an erupting core-field flux rope that has blown out the emerging bipole. We therefore infer that these "two pronged" jets are made by miniature versions of the sheared-core-bipole explosions that produce bubble-type CMEs. This work was funded by NASA s Science Mission Directorate through the Heliophysics Guest Investigators Program, the Hinode Project, and the Living With a Star Targeted Research and Technology Program.

Moore, Ronald L.↗
NASA NTRS2008

The Foggy EUV Corona and Coronal Heating by MHD Waves from Explosive Reconnection Events

In 0.5 arcsec/pixel TRACE coronal EUV images, the corona rooted in active regions that are at the limb and are not flaring is seen to consist of (1) a complex array of discrete loops and plumes embedded in (2) a diffuse ambient component that shows no fine structure and gradually fades with height. For each of two not-flaring active regions, found that the diffuse component is (1) approximately isothermal and hydrostatic and (2) emits well over half of the total EUV luminosity of the active-region corona. Here, from a TRACE Fe XII coronal image of another not-flaring active region, the large sunspot active region AR 10652 when it was at the west limb on 30 July 2004, we separate the diffuse component from the discrete loop component by spatial filtering, and find that the diffuse component has about 60% of the total luminosity. If under much higher spatial resolution than that of TRACE (e. g., the 0.1 arcsec/pixel resolution of the Hi-C sounding-rocket experiment proposed by J. W. Cirtain et al), most of the diffuse component remains diffuse rather being resolved into very narrow loops and plumes, this will raise the possibility that the EUV corona in active regions consists of two basically different but comparably luminous components: one being the set of discrete bright loops and plumes and the other being a truly diffuse component filling the space between the discrete loops and plumes. This dichotomy would imply that there are two different but comparably powerful coronal heating mechanisms operating in active regions, one for the distinct loops and plumes and another for the diffuse component. We present a scenario in which (1) each discrete bright loop or plume is a flux tube that was recently reconnected in a burst of reconnection, and (2) the diffuse component is heated by MHD waves that are generated by these reconnection events and by other fine-scale explosive reconnection events, most of which occur in and below the base of the corona where they are seen as UV explosive events, EUV blinkers, and type II spicules. These MHD waves propagate across field lines and dissipate, heating the plasma in the field between the bright loops and plumes.

Moore, Ron L.↗