For HVC 100-7+100, we have a firm upper distance limit of 1.2 kpc. The cloud consists of two small condensations, for which we have given estimates of size, mass and density. Unless the cloud is very nearby, its density is not much higher than the average density in the Galactic Disk. The cloud lies within the Disk, and has a velocity deviating by at least 100 km s-1 from its surroundings. However, because it is small (especially if it is much nearer than 1 kpc), it may survive (and already have existed) for millions of years. Its origin remains unclear.
For HVC 347+35-112, no distance constraint is available. This feature appears to be part of an extended, low-density HVC, called Complex L. This object is much smaller and less massive than well-known ones such as Complexes A, C, H and M, and its small-scale structure appears to be less pronounced. In other respects it is not unusual.
© European Southern Observatory (ESO) 1998
Online publication: September 8, 1998