High-Resolution X-Ray Spectra of Capella: Initial Results from the Chandra High-Energy Transmission Grating Spectrometer

By C. Canizares, D. Huenemoerder, D. S. Davis, D. Dewey, K. Flanagan, John C. Houck, T. Markert, H. L. Marshall, M. Schattenburg, N. Schulz and 3 more. 2000

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High-resolution spectra of the active binary Capella (G8 III + G1 III) covering the energy range of 0.4-8.0 keV (1.5-30 Å) show a large number of emission lines, demonstrating the performance of the High-Energy Transmission Grating Spectrometer. A preliminary application of plasma diagnostics provides information on coronal temperatures and densities. Lines arising from different elements in a range of ionization states indicate that Capella has plasma with a broad range of temperatures, from log T = 6.3 to 7.2, generally consistent with recent results from observations with the Extreme-Ultraviolet Explorer and the Advanced Satellite for Cosmology and Astrophysics. The electron density is determined from He-like O VII lines, giving the value of Ne ~ 1010 cm-3 at Te ~ 2 × 106 K; He-like lines formed at higher temperatures give only upper limits to the electron density. The density and emission measure from O VII lines together indicate that the coronal loops are significantly smaller than the stellar radius.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/90d688b530b722190232fddb879c077209fa8746

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Citations in the corpus

The Chandra High‐Energy Transmission Grating: Design, Fabrication, Ground Calibration, and 5 Years in Flight (2005, background): “The High Energy Transmission Grating, HETG (Canizares et al. 2000), is one of two objective transmission gratings on Chandra; the Low Energy Transmission Grating, LETG (Brinkman et al. 2000), is of a similar design but optimized for energies less than 1 keV.”
The Chandra High-Energy Transmission Grating Observation of an X-Ray Ionization Cone in Markarian 3 (2000, methodology): “Observation and Data Reduction Mkn 3 was observed with the Chandra HETGS (Canizares et al. 2000) with the ACIS-S array (Garmire et al. 2000) at the focal plane.”
Evidence for Accretion: High-Resolution X-Ray Spectroscopy of the Classical T Tauri Star TW Hydrae (2001, background): “The High Energy Transmission Gratings Spectrometer (HETGS) on Chandra now provides a much more powerful tool for the study of X-ray emission from stars (Canizares et al. 2000).”
Indirect X-Ray Line-Formation Processes in Iron L-Shell Ions (2003, background): “The observations of the solar corona (Rugge & McKenzie 1985), the recent high-resolution X-ray spectra of Capella (Canizares et al. 2000; Behar, Cottam, & Kahn 2001) and II Pegasi (Huenemoerder, Canizares, & Schulz 2001) obtained with Chandra, and that of the elliptical galaxy NGC 4636 obtained…”
The Suzaku High Resolution X-Ray Spectrometer (2007, background): “These devices offer very high spectral resolution for energies below about 1 keV (e.g., Canizares et al. 2000; Brinkman et al. 2000; den Herder et al. 2001), but the spectral resolving power decreases toward higher energies and also degrades as the solid angle of the source being observed increases.”
X-ray spectroscopy of stars (2009, background): “The high-density results have been questioned altogether fromdetailed analyses of the Capella and II Peg spectra, for which upper limits to electron densitie have been derived from Ne, Mg, and Si triplets (Canizares et al, 2000; Ayres et al, 2001a; Huenemoerder et al, 2001; Phillips et al, 2001).”
Toward a Self-Consistent Model of the Ionized Absorber in NGC 3783 (2003, background): “One case has been intensively pursued lately, due to the improvement in the quality of UV and X-ray spectra from STIS, FUSE, and the grating spectrometers on Chandra (HETGS, LETGS) and XMM-Newton (RGS): the highly ionized (or ‘warm’) absorbers that appear in about half of all UV and X-ray spectra of”