Astronomy and Astrophysics – Astronomy
Scientific paper
May 1996
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996apjs..104...81t&link_type=abstract
Astrophysical Journal Supplement v.104, p.81
Astronomy and Astrophysics
Astronomy
11
Ism: Clouds, Ism: Kinematics And Dynamics, Radio Lines: Ism
Scientific paper
High-resolution 21 cm column density maps of neutral hydrogen obtained with the 305 m Arecibo telescope are used to select target stars in a search for optical interstellar absorption lines at high velocities. Four stars are observed toward the high-velocity knot (AC 0) in the anticenter shell. Three stars are observed toward the anti- center chain high-velocity cloud AC I. And five stars are observed toward the high-velocity cloud in Cetus called Cohen's stream. Two additional stars are observed toward the "hook" seen at the southeastern edge of the anti- center shell, even though no high-resolution H I map was obtained for this region.
Optical spectra of the Na I D and Ca II H and K lines obtained with the Hamilton spectrograph on the Lick 3 m telescope show no high-velocity interstellar absorption. The high-resolution H I maps allow the results of an absorption-line nondetection to be characterized more accurately. A target star lying toward the dense small-scale clumps and filaments in the high-velocity gas, but for which there is no optical signature, can be confidently declared to lie in the foreground of the high-velocity gas. The case in which the line of sight to the star intersects the high-velocity cloud, but unfortunately passes through a region with a column density too low to detect, is ruled out by the use of these high-resolution maps, unless there is spatial structure on scales be- low 3'.
The AC 0 and the anticenter shell are strongly constrained to be more than 610 pc from the Sun, with a weaker distance lower limit of 950 pc. If the intermediate-velocity interstellar absorption detected toward LS V+30 31 can be associated with the anticenter shell, then the supershell is closer than 6500 pc. The anticenter chain cloud AC I is almost certainly at least 650 Pc from the Sun. Narrow H I emission lines indicative of cold gas are observed at high velocities in the AC 0 and AC I maps. Cohen's stream is similarly constrained to be at least 350 pc and possibly more than 390 pc from the Sun. The anticenter shell "hook" is further than 350 pc.
No associations
LandOfFree
Distance Constraints to the Anticenter High-Velocity Clouds does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Distance Constraints to the Anticenter High-Velocity Clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Distance Constraints to the Anticenter High-Velocity Clouds will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1357101