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J/A+A/335/85  HST photometry of ESO 338-IG04 globular clusters (Oestlin+, 1998)

Globular clusters in the blue compact galaxy ESO 338-IG04 (Tololo 1924-416), as tracers of the star formation history. Results from HST/WFPC2 observations. Oestlin G., Bergvall N., Roennback J. <Astron. Astrophys. 335, 85 (1998)> =1998A&A...335...85O
ADC_Keywords: Clusters, globular ; Photometry Keywords: galaxies: compact - galaxies: starburst - galaxies: star clusters - galaxies: evolution - galaxies: interaction - galaxies: individual: ESO 338-IG04 = Tol 1924-416 Abstract: Multicolour images of the starbursting metal poor blue compact galaxy ESO 338-IG04 have been obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. In the images we find numerous point-like sources concentrated towards the main body of the galaxy, which we identify as globular cluster candidates. We show that these objects are physically associated with the galaxy and that they are spatially extended. Given their high intrinsic luminosities, these objects cannot be individual stars. Using photometric evolution models we show that the objects constitute a rich population of massive star clusters with ages ranging from a few Myr to 10Gyr, and masses ranging from 104 to more than 107M. There are peaks in the age distribution of the clusters: one with objects ≤30Myr, one at ∼100Myr, one at ∼600Myr, one to two at 2.5-5Gyr and one at ∼10Gyr. The youngest objects are predominantly found in the crowded starburst region. They have properties which agree with what is expected for young globular clusters, although it cannot be excluded that some of them may be dissolved or disrupted. For objects older than a few times 10Myr, the only plausible explanation is that these are globular clusters. The galaxy presently appears to be involved in a merger, which is the probable cause of the present globular cluster formation. The presence of a numerous intermediate age (2.5 to 5Gyr) population of globular clusters, suggests that a previous merger might have occurred. As the starburst fades, this galaxy will become very rich in globular clusters. Transforming all objects to an age comparable to that of Milky Way globular clusters reveals a luminosity function similar to the Galactic. We suggest that this galaxy is the result of a merger between a dwarf elliptical and a gas rich dwarf. The possibility of dating the globular clusters offers an efficient way of studying the history of violent star formation in this and similar galaxies. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 19 27 58.1 -41 34 27 Tol 1924-416 = ESO 338- 4 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 87 64 Photometry of object in the outer sample with m814 < 24 table2.dat 87 60 Photometry of object in the inner sample with m814 < 23.5
Byte-by-byte Description of file: table1.dat table2.dat
Bytes Format Units Label Explanations
1- 2 I2 --- [OBR98] Sequential number (1) 3- 5 A3 --- n_[OBR98] [* ] Note (2) 7- 11 F5.1 pix Xpos X position (3) 13- 17 F5.1 pix Ypos Y position (3) 19- 23 F5.2 mag m814 F814W magnitude (4) 25- 28 F4.2 mag e_m814 rms uncertainty on m814 30- 34 F5.2 mag m555 ? F555W magnitude (4) 36- 39 F4.2 mag e_m555 ? rms uncertainty on m555 41- 45 F5.2 mag m439 ? F439W magnitude (4) 47- 50 F4.2 mag e_m439 ? rms uncertainty on m439 52- 56 F5.2 mag m336 ? F336W magnitude (4) 58- 61 F4.2 mag e_m336 ? rms uncertainty on m336 63- 67 F5.1 mag vMAG Absolute v magnitude (or i if n_VMAG ='*') 68 A1 --- n_vMAG [*] * when absolute i magnitude in VMAG 70 A1 --- l_v-i Limit flag on v-i 71- 75 F5.2 mag v-i v-i colour index 77- 81 F5.2 mag b-v ? b-v colour index 83- 87 F5.2 mag u-b ? u-b colour index
Note (1): Table 1: [OBR98] outer NN, in Simbad Table 2: [OBR98] inner NN, in Simbad Note (2): Note: **: probable background galaxy/foreground star ***: possible background galaxy/foreground star Note (3): The field of ESO 338-IG04 was observed with the PC aperture, centred on RA = 19h 28min 00.23s (2000) DE = -41° 34' 21.2". The pixel scale of the PC CCD is 0.0455 arcseconds, which at a distance of 37.5 Mpc corresponds to 8.27 pc. North is up and east is left. Note (4): Magnitudes refer to the photometric zero-points for Vega. The data have been corrected for Galaic reddening.
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 25-Jun-2001
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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