Query : 2012A&A...541L..10V

2012A&A...541L..10V - Astronomy and Astrophysics, volume 541, L10-10 (2012/5-1)

[CII] 158 µm line detection of the warm ionized medium in the Scutum-Crux spiral arm tangency.


Abstract (from CDS):

The Herschel HIFI GOT C+ Galactic plane [CII] spectral survey has detected strong emission at the spiral arm tangencies. We use the unique viewing geometry of the Scutum-Crux (S-C) tangency near l=30°to detect the warm ionized medium (WIM) component traced by [CII] and to study the effects of spiral density waves on Interstellar Medium (ISM) gas. We compare [CII] velocity features with ancillary HI, 12CO and 13CO data near tangent velocities at each longitude to separate the cold neutral medium and the warm neutral + ionized components in the S-C tangency, then we identify [CII] emission at the highest velocities without any contribution from 12CO clouds, as WIM. We present the GOT C+ results for the S-C tangency. We interpret the diffuse and extended excess [CII] emission at and above the tangent velocities as arising in the electron-dominated warm ionized gas in the WIM. We derive an electron density in the range of 0.2-0.9cm–3 at each longitude, a factor of several higher than the average value from Hα and pulsar dispersion. We interpret the excess [CII] in S-C tangency as shock compression of the WIM induced by the spiral density waves.

Abstract Copyright:

Journal keyword(s): ISM: structure - ISM: general - submillimeter: ISM - infrared: ISM

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Crux-Scutum Spiral Arm reg 12 30 -60.0           ~ 303 0
2 NAME Car-Sgr Arm PoG 15 00 -40.0           ~ 499 1
3 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13915 0

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