The morphology of massive star-forming galaxies at high redshift is often dominated by giant clumps of mass ∼ 10 − 10 M and size ∼ 100 − 1000 pc. Previous studies have proposed that giant clumps might have an important role in the evolution of their host galaxy, particularly in building the central bulge. However, this depends on whether clumps live long enough to migrate from their original lo...

We have carried out a submillimeter continuum and spectroscopic study of the W43 main complex, a massive star-forming region, which harbors a giant H ii region. The maps reveal a filamentary structure containing ∼ 50 fragments with masses of 40− 4 000 M⊙ and typical diameters of 0.25 pc. Their large sizes, large non-thermal velocities (∆v ∼ 5 km s), and high densities (nH2 ∼ 10 6 cm) suggest th...

I propose that the relatively high eccentricity 0.1 ∼< e ∼< 0.4 found in some tidally strongly interacting binary systems, where the mass-losing star is an evolved giant star, e.g., an asymptotic giant branch star, is caused by an enhanced mass loss rate during periastron passages. Tidal interaction by itself will circularize the orbits of these systems in a relatively short time, hence a mecha...

The recent discovery of high frequency oscillations during giant flares from the Soft Gamma Repeaters SGR 1806-20 and SGR 1900+14 may be the first direct detection of vibrations in a neutron star crust. If this interpretation is correct it offers a novel means of testing the neutron star equation of state, crustal breaking strain, and magnetic field configuration. We review the observational da...

We investigate the observed depletion of red giants in the cores of post-core-collapse globular clusters. In particular, the evolutionary scenario we consider is a binary consisting of two lowmass stars which undergoes two common-envelope phases. The first common-envelope phase occurs when the primary is a red giant resulting in a helium white dwarf and main-sequence star in a detached binary. ...

How and where do stars form? One of the challenges in star formation theory today is describing the different processes by which stars form. They form not only in isolation, but also in groups of 10-100 stars and in clusters of more than 100 stars. The particular mode of star formation may depend on the initial conditions. Stars form in molecular clouds, regions of dense gas and dust, that can ...

We present HST/NICMOS observations of a sample of LIRGs. We show that active star formation appears to be occurring not only in the bright nuclei of these galaxies, but also in luminous super-star clusters and giant H ii regions with ages of up to 20− 40Myr. This population of bright clusters and H ii regions is unprecedented in normal galaxies and emphasizes the effects of the extreme star for...

A spectroscopic, photometric and evolutionary study is presented for HD 112989, an active peculiar giant star. The present spectroscopic observations show a significant CaII K&H emission core variability, whereas the UBV photometry shows that HD 112989 has a variable brightness. The rotational velocity for this star, 11.0 kms−1, is about five times larger than the mean rotational velocity for g...

Star complexes are the largest globular regions of star formation in galaxies. If there is a spiral density wave, nuclear ring, tidal arm, or other welldefined stellar structure, then gravitational instabilities in the gaseous component produce giant cloud complexes with a spacing of about three times the width. These gas complexes form star complexes, giving the familiar beads on a string of s...