Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-Atlas: An Online Archive of Chandra's Stellar High Energy Transmission
  Gratings Observations   The high-resolution X-ray spectroscopy made possible by the 1999 deployment
of the Chandra X-ray Observatory has revolutionized our understanding of
stellar X-ray emission. Many puzzles remain, though, particularly regarding the
mechanisms of X-ray emission from OB stars. Although numerous individual stars
have been observed in high-resolution, realizing the full scientific potential
of these observations will necessitate studying the high-resolution Chandra
dataset as a whole. To facilitate the rapid comparison and characterization of
stellar spectra, we have compiled a uniformly processed database of all stars
observed with the Chandra High Energy Transmission Grating (HETG). This
database, known as X-Atlas, is accessible through a web interface with
searching, data retrieval, and interactive plotting capabilities. For each
target, X-Atlas also features predictions of the low-resolution ACIS spectra
convolved from the HETG data for comparison with stellar sources in archival
ACIS images. Preliminary analyses of the hardness ratios, quantiles, and
spectral fits derived from the predicted ACIS spectra reveal systematic
differences between the high-mass and low-mass stars in the atlas and offer
evidence for at least two distinct classes of high-mass stars. A high degree of
X-ray variability is also seen in both high and low-mass stars, including
Capella, long thought to exhibit minimal variability. X-Atlas contains over 130
observations of approximately 25 high-mass stars and 40 low-mass stars and will
be updated as additional stellar HETG observations become public. The atlas has
recently expanded to non-stellar point sources, and Low Energy Transmission
Grating (LETG) observations are currently being added as well.

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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: cs
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The categories of this paper are: q-fin
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin