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RISS 인기검색어
- 검색키워드
- 저자 : Heather L. Johnson (검색결과 4 건)
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To Make Live : Representing and Protesting Refugee Agency
Heather L. Johnson 부산대학교 한국민족문화연구소 2016 Localities Vol.6 No.-
Dominant representations of refugees emphasize either refugees as victims or as threats. In the shifts since the outset of the refugee regime, the political agency of refugees has stopped being something to celebrate and is now read as threatening – particularly when that agency is expressed in the choice to move and to cross borders. This control of political agency represents a particular form of governmentality, which maintains a biopolitical order that is framed around the structures of citizenship. The resulting exclusion of refugees as non-citizens has created what is called here a necropolitical outside, where the power over death remains the crucial moment of decision and which can be seen most clearly in the Mediterranean. Nevertheless, in developing patterns of refugee protest and occupation throughout Europe this exclusion is being contested as refugees establish themselves as political subjects in their own right, challenging the order with new forms of conduct and ‘making themselves live’ by making themselves visible.
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GLOBULAR AND OPEN CLUSTERS OBSERVED BY SDSS/SEGUE: THE GIANT STARS
Morrison, Heather L.,Ma, Zhibo,Clem, James L.,An, Deokkeun,Connor, Thomas,Schechtman-Rook, Andrew,Casagrande, Luca,Rockosi, Constance,Yanny, Brian,Harding, Paul,Beers, Timothy C.,Johnson, Jennifer A. American Astronomical Society 2016 The Astronomical journal Vol.151 No.1
<P>We present griz observations for the clusters M92, M13 and NGC 6791 and gr photometry for M71, Be 29 and NGC 7789. In addition we present new membership identifications for all these clusters, which have been observed spectroscopically as calibrators for the Sloan Digital Sky Survey (SDSS)/SEGUE survey; this paper focuses in particular on the red giant branch stars in the clusters. In a number of cases, these giants were too bright to be observed in the normal SDSS survey operations, and we describe the procedure used to obtain spectra for these stars. For M71, we also present a new variable reddening map and a new fiducial for the gr giant branch. For NGC 7789, we derived a transformation from T-eff to g-r for giants of near solar abundance, using IRFM T-eff measures of stars with good ugriz. and 2MASS photometry and SEGUE spectra. The result of our analysis is a robust list of known cluster members with correctly dereddened and (if needed) transformed gr photometry for crucial calibration efforts for SDSS and SEGUE.</P>
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THE SEGUE K GIANT SURVEY. III. QUANTIFYING GALACTIC HALO SUBSTRUCTURE
Janesh, William,Morrison, Heather L.,Ma, Zhibo,Rockosi, Constance,Starkenburg, Else,Xue, Xiang Xiang,Rix, Hans-Walter,Harding, Paul,Beers, Timothy C.,Johnson, Jennifer,Lee, Young Sun,Schneider, Donald American Astronomical Society 2016 The Astrophysical journal Vol.816 No.2
<P>We statistically quantify the amount of substructure in the Milky Way stellar halo using a sample of 4568 halo K giant stars at Galactocentric distances ranging over 5-125 kpc. These stars have been selected photometrically and confirmed spectroscopically as K giants from the Sloan Digital Sky Survey's Sloan Extension for Galactic Understanding and Exploration project. Using a position-velocity clustering estimator (the 4distance) and a model of a smooth stellar halo, we quantify the amount of substructure in the halo, divided by distance and metallicity. Overall, we find that the halo as a whole is highly structured. We also confirm earlier work using blue horizontal branch (BHB) stars which showed that there is an increasing amount of substructure with increasing Galactocentric radius, and additionally find that the amount of substructure in the halo increases with increasing metallicity. Comparing to resampled BHB stars, we find that K giants and BHBs have similar amounts of substructure over equivalent ranges of Galactocentric radius. Using a friends-of-friends algorithm to identify members of individual groups, we find that a large fraction (similar to 33%) of grouped stars are associated with Sgr, and identify stars belonging to other halo star streams: the Orphan Stream, the Cetus Polar Stream, and others, including previously unknown substructures. A large fraction of sample K giants (more than 50%) are not grouped into any substructure. We find also that the Sgr stream strongly dominates groups in the outer halo for all except the most metal-poor stars, and suggest that this is the source of the increase of substructure with Galactocentric radius and metallicity.</P>
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Lee, Young Sun,Beers, Timothy C.,An, Deokkeun,Ivezić,, Ž,eljko,Just, Andreas,Rockosi, Constance M.,Morrison, Heather L.,Johnson, Jennifer A.,Schö,nrich, Ralph,Bird, Jonathan,Yanny, Brian IOP Publishing 2011 The Astrophysical journal Vol.738 No.2
<P>We employ measurements of the [alpha/Fe] ratio derived from low-resolution (R similar to 2000) spectra of 17,277 G-type dwarfs from the SEGUE survey to separate them into likely thin-and thick-disk subsamples. Both subsamples exhibit strong gradients of orbital rotational velocity with metallicity, of opposite signs, -20 to -30 km s(-1) dex(-1) for the thin-disk and + 40 to + 50 km s(-1) dex(-1) for the thick-disk population. The rotational velocity is uncorrelated with Galactocentric distance for the thin-disk subsample and exhibits a small trend for the thick-disk subsample. The rotational velocity decreases with distance from the plane for both disk components, with similar slopes (-9.0 +/- 1.0 km s(-1) kpc(-1)). Thick-disk stars exhibit a strong trend of orbital eccentricity with metallicity (about -0.2 dex(-1)), while the eccentricity does not change with metallicity for the thin-disk subsample. The eccentricity is almost independent of Galactocentric radius for the thin-disk population, while a marginal gradient of the eccentricity with radius exists for the thick-disk population. Both subsamples possess similar positive gradients of eccentricity with distance from the Galactic plane. The shapes of the eccentricity distributions for the thin-and thick-disk populations are independent of distance from the plane, and include no significant numbers of stars with eccentricity above 0.6. Among several contemporary models of disk evolution that we consider, radial migration appears to have played an important role in the evolution of the thin-disk population, but possibly less so for the thick disk, relative to the gas-rich merger or disk heating scenarios. We emphasize that more physically realistic models and simulations need to be constructed in order to carry out the detailed quantitative comparisons that our new data enable.</P>
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