WIDESPREAD ROTATIONALLY HOT HYDRONIUM ION IN THE GALACTIC INTERSTELLAR MEDIUM

Widespread Rotationally-hot Hydronium Ion in the Galactic Interstellar Medium

We present new Herschel observations of the (6,6) and (9,9) inversion transitions of the hydronium ion toward Sagittarius B2(N) and W31C. Sensitive observations toward Sagittarius B2(N) show that the high, ∼500 K, rotational temperatures characterizing the population of the highly-excited metastable H3O + rotational levels are present over a wide range of velocities corresponding to the Sagitta...

Hot, metastable hydronium ion in the Galactic centre: formation pumping in X-ray-irradiated gas?

With a 3.5 m diameter telescope passively cooled to approximately 80 K, and a science payload comprising two direct detection cameras/medium resolution imaging spectrometers (PACS and SPIRE) and a very high spectral resolution heterodyne spectrometer (HIFI), the Herschel Space Observatory is providing extraordinary observational opportunities in the 55-670 μm spectral range. HIFI has opened for...

X-ray Absorption Line Spectroscopy of the Galactic Hot Interstellar Medium

We present an X-ray absorption line spectroscopic study of the large-scale hot interstellar medium (HISM) in the Galaxy. We detect Ne IX K α absorption lines in the Chandra grating spectra of seven Galactic low-mass X-ray bi-naries. Three of these sources also show absorption of O VII K α , O VII K β , and/or O VIII K α. Both centroid and width of the lines are consistent with a Galactic HISM o...

Detection of in the Diffuse Interstellar Medium: the Galactic Center

Absorption lines of have been detected in the spectra of two infrared sources in the Galactic 3 center and also toward the heavily reddened star Cygnus OB2 No. 12, whose line of sight is believed to include only di†use interstellar gas. The absorptions toward the Galactic center sources (IRS 3 and GCS 3-2) probably are due to both in di†use gas and in molecular clouds. The ratios of line equiva...

The 3 - D composition of the Galactic interstellar medium . The hot phases and X - ray absorbing material