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We present integrated Washington CT1 photometry of 18 bright blue objects discovered in the dwarf galaxy UGC 7636 which is located 5.5 southeast of the giant elliptical galaxy NGC 4472, the brightest galaxy in the Virgo cluster. Several lines of evidence indicate that UGC 7636 is interacting violently with NGC 4472. These objects are very blue with colors of -0.4 < (C-T1) < 0.6, and their magnitudes are in the range of 20.6 < T1 < 22.9 mag which corresponds to absolute magnitudes of -10.6 < M(T1) < -8.3 mag for a distance modulus of (m-M)o = 31.2. These objects are grouped spatially in three regions: the central region of UGC 7636, the tidal tail region, and the HI cloud region. No such objects were found in the counter tail region. It is concluded that these objects are probably young star clusters which formed < 0.1Gyr ago during the interaction between UGC 7636 and NGC 4472. Surface photometry of UGC 7636 (r < 83) shows that there is a significant excess of blue light along the tidal tail region compared with other regions. The star clusters are bluer than the stellar light in the tidal tail region, indicating that these clusters might have formed later than most stars in the tidal tail region which were formed later than most stars in the main body of the galaxy.
We present X-ray spectroscopic and morphological analyses using Chandra ACIS and ROSAT observations of the giant elliptical galaxy NGC 4472 in the Virgo cluster. We discuss previously unobserved X-ray structures within the extended galactic corona. I
We present the first Advanced Camera for Surveys (ACS) observations of young star clusters in the colliding/merging galaxy UGC 10214. The observations were made as part of the Early Release Observation (ERO) program for the newly installed ACS during
We present results of the analysis of photometric and spectroscopic observations of the young stellar complexes in the late giant spiral galaxy UGC 11973. Photometric analysis in the UBVRI bands have been carried out for the 13 largest complexes. For
The distance to NGC 5128, the central galaxy of the Centaurus group and the nearest giant elliptical to us, has been determined using two independent distance indicators: the Mira period-luminosity (PL) relation and the luminosity of the tip of the r
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