We suggest and give some evidence that as an HII region expands and the O stars evolve into B giants, remains of the molecular clouds first appear as bright-rimmed clouds, then as cometary globules and finally as small clouds which are visible by the reflected light from the B giants. We propose to call the last of these ‘reflection clouds’ and all three categories collectively ‘remnant clouds’. A list is presented of about 80 objects of these remnant clouds in the Ori OB 1 association. In the Belt region there is a beautiful spatial sequence from bright-rimmed clouds through cometary globules to reflection clouds. We suspect that retarded star formation in remnant clouds can explain the presence of so-called dispersed T Tau stars in the peripheries of OB associations.

Altogether 26 new Herbig-Haro (HH) objects have been discovered by slit spectroscopy and narrow-band CCD imagery. Several of them are very remarkable in various aspects. We have also found a total of over 1000 HH candidates in L1641, L1630 and NGC 2264 on deep Schmidt plates. Fibre spectroscopy is currently underway, confirming already some 70 HH objects. Implications of this large number are briefly discussed.

We have carried out an extensive survey of Hα emission stars in the Orion region over an area of about 100 deg2. We present the results for the areas A-0975 and A-0976 of about 25 deg2 each.

According to McCarthy (1984) the objects detected in objective prism surveys for Hα emission line are a ”most unnatural“ group. Of course they consist of many natural groupings whose identities or other peculiarities could become apparent after observing them with higher dispersion and resolution spectroscopy. In some cases, however, their galactic locations and associations with other known populations, can provide a clue to their population types.

The aims of the objective prism surveys using the Bosscha Schmidt telescope can be broadly categorised as follows:

1. 1. Searches for galactic planetary nebulae in the region 240° < l < 360 °; |b| ≤ 10°, initiated by The (1968).

2. 2. Searches for T-Tauri stars in some southern dark clouds (Shinohara, Ogura & Hidayat 1989).

3. 3. Searches for variations in Hα intensities and luminous emission stars in some selected galactic regions, such as in the Puppis and Carina regions.

About 1300, 60 and 70 Herbig-Haro candidates have been picked up in the Ori A/L1641, Ori B/L1630 and NGC 2264/Mon OBI regions, respectively, on deep Schmidt plates. The contrast enhancement and unsharp masking technique has been applied simultaneously. Unsharp masking applied to an objective-prism Schmidt plate for the Carina Nebula region has yielded the detection of 38 Hα emission stars, of which 13 are new findings.

We have reported NMA observations of HH83 with CS (J=2-l) line. The interacton between the outflow and the molecluar cloud is found.

We present preliminary results of a survey of bright-rimmed clouds associated with IRAS point sources.

Bright-rimmed globules associated with old HII regions have long been suspected as a potential site for star formation. Physical conditions of such clouds seem to well match to models of radiation-driven implosion, which have been studied as an effective process for induced star formation (e.g. Klein et al. 1985, Bertoldi 1989). Bright-rimmed globules associated with IRAS point sources are good candidates for the sites of induced star formation. Three well-established cases of radiation-driven implosions in bright-rimmed globules (Ori I-2, IC1396-n, and L1206) were reported (Sugitani et al. 1989). Similar examples were also reported in HH46/47 (Olberg et al. 1989) and in GN21.38.9 (Duvert et al. 1990). However, the samples are still not numerous enough to establish comprehensive understanding of star formation by such implosion process.

So far discoveries of Herbig-Haro objects were done mainly by either of two different methods. The first relies on their non-stellar appearances on direct photographs, followed by low-dispersion slit spectroscopy; this is the most standard method. But sometimes only the former step is made; then picked-up objects are possible HH objects (e.g. Gyul'budagyan 1982, and Reipurth 1985). The second is based on objective-prism observations in the red with Schmidt telescopes. We have invented a third method to find new HH objects. This utilizes Schmidt telescopes, too, but can reach a fainter limiting-magnitude than that obtained with objective-prism observations.

The M17SW giant molecular cloud extends over 4° (∼ 160 pc) at the south-west of the giant H II region M17. The distance and the mass of the cloud are estimated to be approximately 2.2 kpc and 3x105 M⊙, respectively.

A cometary globule in IC1396 named ”comet tail 6” by Osterbrock (1957), has been observed at CO and 13CO (J = 1-0) lines with a high spatial resolution, 14″, with the 45-m radio telescope at the Nobeyama Radio Observatory. The resolution corresponds to a linear size of 0.05 pc at the distance of 750 pc (Matthews 1979). Two possible pre-main sequence stars, LkHα 349 and LkHα 349/c (Cohen and Kuhi 1979), associated with small nebulosities nestle in the central part of the globule. We have obtained CO and 13CO spectra long NS and EW strips which cross each other at the position of LkHα 349 and have mapped a 1.5′x1.5′ area around the globule center at 13CO. Results from the observations are summarized as follows:

The most direct approach to the suggested relationship of Bok globules to star formation is to search for actual spots of star birth in or around them. But no protostellar objects have hitherto been found by infrared and/or radio observations. Optically relevant to this are the discoveries of some Herbig-Haro objects and pre-main sequence stars associated with cometary globules inside the Gum Nebula (Reipurth 1983).