High-dispersion spectroscopic observations with good spectral resolution have been made of the four clumps in the two clumpy irregular galaxies Markarian 297 and 325. Their velocity dispersions in the Hα emission line (32-41 km s−1) are larger by about 2 or more than those of the so-called giant HII regions in nearby spiral or irregular galaxies.

The four clumpy irregular galaxies Mkr 8, 296,297 and 325 have been observed by IRAS. All galaxies have been detected in at least two of the four detector bands. The ratios of the 100 to 60-m flux densities are comparable to those of HII regions or violently star forming galaxies. The average star formation rate in clumpy irregular galaxies is of the order of a few solar masses per year (based on their average far-infrared luminosity and a Hubble constant of 75 km s−1 Mpc−1.

A survey of Kiso UV-excess galaxies (KUGs) has been made using the 105-cm Kiso Schmidt telescope. We selected three galaxies of Ic-type (i.e. irregulars with clumpy HII regions). KUGs 1618+373, 1624+404 and 1626+413, and observed them together with a clumpy irregular galaxy Mrk 297 to clarify their star formation activity (Maehara et al. 1986).

The galaxy-galaxy interaction has been proposed as a possible triggering mechanism of the star formation bursts in some galaxies (e.g. Larson and Tinsley 1978). To investigate the nature of star formation bursts triggered by interaction we have numerically simulated close encounters between disk galaxies, taking the star formation process into account (see Noguchi and Ishibashi 1986 for details). We used the cloud-particle model, in which gas clouds move as test particles in the gravitational field of the galaxies. When two clouds collide with each other, an OB-star is formed. The cloud system loses its kinetic energy by inelastic cloud-cloud collisions. The supernova explosion which follows the formation of an OB-star provides kinetic energy to the nearby clouds.

CO emission has been detected from 75 bright infrared galaxies with CZ = 2 000 – 16 000 km/s. These include the most distant and the most luminous galaxies (Arp 55, IR 1713+63) yet detected in CO. All of these galaxies are rich in molecular gas with Mtotal (H2) = 2 × 109 −6x1010 M⊙, and they have a strong far-infrared excess, with LFIR/LB = 2-40 and LFIR (40-400μ) = 1010 – 3 × 1012 L⊙. The primary luminosity source appears to be star formation in molecular clouds. A strong correlation is found between the FIR and 21-cm continuum flux, implying that the IMF is independent of the star formation rate. The ratio LFIR/M(H2) provides a measure of the current rate of star-formation, which is found to be a factor 3-20 larger in these galaxies than for the ensemble of molecular clouds in the Milky Way. VLA maps plus a few high resolution (14″-30″) CO (1-0) and CO (2-1) maps suggest that most of the luminosity comes from core regions 1-3 kpc in size. The abnormal concentration of molecular gas in these galactic cores is presumably the result of a collision or strong interaction with a nearby companion.

The starburst galaxy Tol 1924-416 was observed on May 18, 1985 using an echelle spectrograph coupled with a cooled CCD camera (CASPEC) mounted at the Cassegrain focus of the ESO 3.6-m telescope. The echellogram covers the 4320-5260 A spectral range with 0.33 A/pixel and a spatial extent of 12 arcsec at 1.5 arcsec seeing. The estimated spectral resolution is 25 kms−1 and the velocity calibration error is as small as 3 km s−1.

A survey of UV-excess galaxies (KUGs) has been made on UGR three image plates taken with the 105-cm Kiso Schmidt telescope (105/150/330) by Takase and Miyauchi-Isobe (1984, 1985a,b). Up to now, about 1 800 objects down to 17-17.5 mag have been catalogued in the surveyed areas of about 900 square degrees.

We present results on correlations between gas mass in spiral galaxies and their FIR and blue luminosities. We have used the published 12CO emission data of the University of Massachusetts and the FIR data from IRAS Galaxy Catalogue. In order to derive the H2 mass from 12CO data, we have used a relation of the form, N(H2) = A TA dV cm−2 with A = 2x1020 K−1 km s−1 cm−2. The total gas mass Mg was obtained using an additional factor of 1.36 to take care of the fraction of mass in He. Those galaxies that were classified as peculiar, interacting or included in Arp's catalogue were termed peculiar and the rest normal.

The flocculent spiral galaxy NGC 5055 has been mapped along the major axis in the 12CO (J = 1-0) line using the Onsala 20-m telescope (HPBW = 33″). Figure 1, which gives the spatial velocity diagram of CO emission on the major axis with observed Hα velocities (Kruit and Bosma, 1978) superimposed, seems to imply higher velocities of the regions responsible for the optical emission. Taking into account the cruder spatial resolution of the CO observations, this effect is expected in a region where the rotation curve rises rapidly provided that the CO emission increases toward the centre. Figure 2 shows the rotation velocities for the eastern and western parts of the galaxy separately, as observed in Hα and CO. For CO we only give the portion of the rotation curve which is accurately determined, i.e. where it is relatively flat. The CO velocities in this region agree closely with those observed in HI (Bosma, 1978). These data suggest a difference of 10-20 km s−1 between the Hα and CO velocities at a distance of ∼ 60″ from the centre. The radial distribution of the CO emission, also indicated in Fig. 2, is defined by an iterative fitting procedure to the observed line profiles (see Scoville et al. 1983). This procedure requests an a priori knowledge of the velocity field, here assumed to be defined by the Hα data inside a radius of 60″. However, the shapes of the observed spectra and “best fit” model profiles differ significantly in some cases, again indicating that the Hα velocities do not apply to the molecular gas. The derived radial distribution of the CO emission is dependent on the assumed velocity field; however, the gross characteristics are retained for more feasible rotation curves (i.e. rotation curves giving better fits to the observed profiles).

We present observations of the Scd galaxy IC 342 in the J = 1-0 transition of CO, performed with the Onsala 20-m antenna. The spectra were obtained in a beamswitch mode.

Three topics in star formation theory are reviewed: the initial mass function, the star formation efficiency, and the star formation rate. A physical mechanism for bimodal star formation is developed. Applications are made to the solar neighborhood, to the inner galaxy, to starburst galaxies, and to past star formation in protodisks and in protoellipticals. Implications are drawn for galactic morphology, for chemical evolution, and for the present density of stellar remnants.

Interchange processes in the interstellar medium, which is composed of diffuse gas, small clouds and giant molecular clouds are examined. It is stressed that the formation of giant molecular clouds through gravitational instability of a cloud ensemble leads to periodic star formation. The evolution of galaxies with such periodic star formation episodes is studied, especially paying attention to the effect of gas infall.

The history of star formation in our galaxy is written in the metal abundance distributions of the stellar populations. Any star formation model is constrained by two facts. First, there was a period in the early stages of galactic evolution during which the metallicity of the gas out of which stars were being formed was significantly lower than the present epoch. Second, there is a paucity of extremely metal deficient stars in the disk of the galaxy.

UKIRT offers unique flexibility in the range of instrumentation available to study starforming regions in the infrared. Because of this many aspects of starformation are currently under study and the latest developments from UKIRT are reviewed. Work ranges from detailed high resolution spectroscopic studies of outflow sources to IRAS “follow-up” of molecular clouds and large scale starformation in normal and interacting galaxies.

A new 4-m millimeter wave telescope has been constructed at the Department of Physics and Astrophysics, of Nagoya University, mainly for the purpose of making rapid surveys of interstellar molecular lines. The observing site is located on the Higashiyama Campus of the University at an altitude of 70-m above sea level in Nagoya. Observations with this telescope started in December 1983.

We report the present status in the development of the millimeter-wave low noise receiver at Nagoya University.