MEASUREMENTS OF NON-THERMAL LINE WIDTHS IN SOLAR ACTIVE REGIONS
ABSTRACT Spectral line widths are often observed to be larger than can be accounted for by thermal and instrumental broadening alone. This excess broadening is a key observational constraint for both nanoflare and wave dissipation models of coronal heating. Here we present a survey of non-thermal ve...
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| Veröffentlicht in: | The Astrophysical journal 2016-03, Vol.820 (1), p.63-63 |
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| creator | Brooks, David H. Warren, Harry P. |
| description | ABSTRACT Spectral line widths are often observed to be larger than can be accounted for by thermal and instrumental broadening alone. This excess broadening is a key observational constraint for both nanoflare and wave dissipation models of coronal heating. Here we present a survey of non-thermal velocities measured in the high temperature loops (1-4 MK) often found in the cores of solar active regions. This survey of Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) observations covers 15 non-flaring active regions that span a wide range of solar conditions. We find relatively small non-thermal velocities, with a mean value of 17.6 5.3 km s−1, and no significant trend with temperature or active region magnetic flux. These measurements appear to be inconsistent with those expected from reconnection jets in the corona, chromospheric evaporation induced by coronal nanoflares, and Alfvén wave turbulence models. Furthermore, because the observed non-thermal widths are generally small, such measurements are difficult and susceptible to systematic effects. |
| doi_str_mv | 10.3847/0004-637X/820/1/63 |
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J</addtitle><description>ABSTRACT Spectral line widths are often observed to be larger than can be accounted for by thermal and instrumental broadening alone. This excess broadening is a key observational constraint for both nanoflare and wave dissipation models of coronal heating. Here we present a survey of non-thermal velocities measured in the high temperature loops (1-4 MK) often found in the cores of solar active regions. This survey of Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) observations covers 15 non-flaring active regions that span a wide range of solar conditions. We find relatively small non-thermal velocities, with a mean value of 17.6 5.3 km s−1, and no significant trend with temperature or active region magnetic flux. These measurements appear to be inconsistent with those expected from reconnection jets in the corona, chromospheric evaporation induced by coronal nanoflares, and Alfvén wave turbulence models. Furthermore, because the observed non-thermal widths are generally small, such measurements are difficult and susceptible to systematic effects.</description><subject>ALFVEN WAVES</subject><subject>ASTROPHYSICS, COSMOLOGY AND ASTRONOMY</subject><subject>Coronas</subject><subject>DATA ANALYSIS</subject><subject>Dissipation</subject><subject>EMISSION SPECTRA</subject><subject>EVAPORATION</subject><subject>EXTREME ULTRAVIOLET RADIATION</subject><subject>HEATING</subject><subject>Imaging spectrometers</subject><subject>JETS</subject><subject>LIMITING VALUES</subject><subject>LINE BROADENING</subject><subject>LINE WIDTHS</subject><subject>MAGNETIC FLUX</subject><subject>methods: data analysis</subject><subject>Nanostructure</subject><subject>SOLAR CORONA</subject><subject>SOLAR FLARES</subject><subject>SUN</subject><subject>Sun: corona</subject><subject>Sun: UV radiation</subject><subject>TURBULENCE</subject><subject>VELOCITY</subject><issn>0004-637X</issn><issn>1538-4357</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2016</creationdate><recordtype>article</recordtype><recordid>eNqN0E1PgzAYwPHGaOKcfgFPJHrwwugbpZwMmWwjYZAAU29NV0pk2QZSdvDbyzKzkzH20jb5Pc_hD8A9ghPCqedACKnNiPfucAwd5DByAUbIJdymxPUuwegMrsGNMZvjF_v-CDwvwyBfZeEyTIrcSmdWkiZ2sQizZRBbcZSE1lv0UixyK0qsPI2DzAqmRfQaWlk4j9IkvwVXldwaffdzj8FqFhbThR2n82gaxLZyGe9tjiCtEKKcaI9wgnwuNVl7HCqufUh9ikqJ9XA4X0MJFYaqdEtPS7aWDMqSjMHDaW9j-loYVfdafahmv9eqFxi7GFHEBvV0Um3XfB606cWuNkpvt3Kvm4MRiPuEc8Iw_QflyGOIQXeg-ERV1xjT6Uq0Xb2T3ZdAUBzzi2NOcawrhvwCDc9h6PE0VDet2DSHbj_kEbLdnIloy2pgk1_YH3u_AaX5iqg</recordid><startdate>20160320</startdate><enddate>20160320</enddate><creator>Brooks, David H.</creator><creator>Warren, Harry P.</creator><general>The American Astronomical Society</general><scope>AAYXX</scope><scope>CITATION</scope><scope>7TG</scope><scope>KL.</scope><scope>8FD</scope><scope>H8D</scope><scope>L7M</scope><scope>OTOTI</scope><orcidid>https://orcid.org/0000-0002-2189-9313</orcidid><orcidid>https://orcid.org/0000-0001-6102-6851</orcidid></search><sort><creationdate>20160320</creationdate><title>MEASUREMENTS OF NON-THERMAL LINE WIDTHS IN SOLAR ACTIVE REGIONS</title><author>Brooks, David H. ; Warren, Harry P.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c568t-8104f11483e7383198ae3b780c8e904941da2eeee88b0a0c20cd5d7ea6ba60ad3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2016</creationdate><topic>ALFVEN WAVES</topic><topic>ASTROPHYSICS, COSMOLOGY AND ASTRONOMY</topic><topic>Coronas</topic><topic>DATA ANALYSIS</topic><topic>Dissipation</topic><topic>EMISSION SPECTRA</topic><topic>EVAPORATION</topic><topic>EXTREME ULTRAVIOLET RADIATION</topic><topic>HEATING</topic><topic>Imaging spectrometers</topic><topic>JETS</topic><topic>LIMITING VALUES</topic><topic>LINE BROADENING</topic><topic>LINE WIDTHS</topic><topic>MAGNETIC FLUX</topic><topic>methods: data analysis</topic><topic>Nanostructure</topic><topic>SOLAR CORONA</topic><topic>SOLAR FLARES</topic><topic>SUN</topic><topic>Sun: corona</topic><topic>Sun: UV radiation</topic><topic>TURBULENCE</topic><topic>VELOCITY</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Brooks, David H.</creatorcontrib><creatorcontrib>Warren, Harry P.</creatorcontrib><collection>CrossRef</collection><collection>Meteorological & Geoastrophysical Abstracts</collection><collection>Meteorological & Geoastrophysical Abstracts - Academic</collection><collection>Technology Research Database</collection><collection>Aerospace Database</collection><collection>Advanced Technologies Database with Aerospace</collection><collection>OSTI.GOV</collection><jtitle>The Astrophysical journal</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext_linktorsrc</fulltext></delivery><addata><au>Brooks, David H.</au><au>Warren, Harry P.</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>MEASUREMENTS OF NON-THERMAL LINE WIDTHS IN SOLAR ACTIVE REGIONS</atitle><jtitle>The Astrophysical journal</jtitle><stitle>APJ</stitle><addtitle>Astrophys. J</addtitle><date>2016-03-20</date><risdate>2016</risdate><volume>820</volume><issue>1</issue><spage>63</spage><epage>63</epage><pages>63-63</pages><issn>0004-637X</issn><eissn>1538-4357</eissn><abstract>ABSTRACT Spectral line widths are often observed to be larger than can be accounted for by thermal and instrumental broadening alone. This excess broadening is a key observational constraint for both nanoflare and wave dissipation models of coronal heating. Here we present a survey of non-thermal velocities measured in the high temperature loops (1-4 MK) often found in the cores of solar active regions. This survey of Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) observations covers 15 non-flaring active regions that span a wide range of solar conditions. We find relatively small non-thermal velocities, with a mean value of 17.6 5.3 km s−1, and no significant trend with temperature or active region magnetic flux. 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| subjects | ALFVEN WAVES ASTROPHYSICS, COSMOLOGY AND ASTRONOMY Coronas DATA ANALYSIS Dissipation EMISSION SPECTRA EVAPORATION EXTREME ULTRAVIOLET RADIATION HEATING Imaging spectrometers JETS LIMITING VALUES LINE BROADENING LINE WIDTHS MAGNETIC FLUX methods: data analysis Nanostructure SOLAR CORONA SOLAR FLARES SUN Sun: corona Sun: UV radiation TURBULENCE VELOCITY |
| title | MEASUREMENTS OF NON-THERMAL LINE WIDTHS IN SOLAR ACTIVE REGIONS |
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