First Light Measurements of Capella with the Low-Energy Transmission Grating Spectrometer aboard the Chandra X-Ray Observatory.
We present the first X-ray spectrum obtained by the Low-Energy Transmission Grating Spectrometer (LETGS) aboard the Chandra X-Ray Observatory. The spectrum is of Capella and covers a wavelength range of 5-175 Å (2.5-0.07 keV). The measured wavelength resolution, which is in good agreement with ground calibration, is Deltalambda approximately 0.06 Å (FWHM). Although in-flight calibration of the LETGS is in progress, the high spectral resolution and unique wavelength coverage of the LETGS are well demonstrated by the results from Capella, a coronal source rich in spectral emission lines. While the primary purpose of this Letter is to demonstrate the spectroscopic potential of the LETGS, we also briefly present some preliminary astrophysical results. We discuss plasma parameters derived from line ratios in narrow spectral bands, such as the electron density diagnostics of the He-like triplets of carbon, nitrogen, and oxygen, as well as resonance scattering of the strong Fe xvii line at 15.014 Å.
Brinkman
AC
Gunsing
CJ
Kaastra
JS
van Der Meer RL
Mewe
R
Paerels
F
Raassen
AJ
van Rooijen JJ
Bräuninger
H
Burkert
W
Burwitz
V
Hartner
G
Predehl
P
Ness
J
Schmitt
JH
Drake
JJ
Johnson
O
Juda
M
Kashyap
V
Murray
SS
Pease
D
Ratzlaff
P
Wargelin
BJ