Southern Galaxies.IV. Isophotometry of the Large Barred Spiral NGC 6744.
Abstract
Isophotes and photometric parameters of the large southern spiral NGC 6744, revised type SAB(r)bc, are derived from photographs taken with the Mount Stromlo 30-inch and 74-inch reflectors. The total apparent photographic magnitude m = 9.45 (with provisional zero point) and maximum dimensions 23' X 14' (at the threshold i#m 27.0 mag = 0.70/pc2) correspond to MT = -19.15 and Dm = 27.6 kpc, if m - M = 28.6 and A = 4.2 Mpc. A faint, dwarf irregular satellite, type Im, measuring 1 6 X 0.4 and located 10.5 from the center in p.a. 318 is attached at the extremity of a very faint anomalous arm. Excluding it the major axis of the regular spiral pattern is in position angle 0 15 and the mean axis ratio of the outer isophotes q = <b/a> = 0.64 corresponds to an inclination j = 52 . The length of the bar is in p.a. 0i = 187 in a narrow elliptical ring (r) = 3 15 X 1 95. The equivalent effective radius is r_* - 3'18 = 3.8 kpc, the effective surface brightness = 23.60 mag sec = 28.70/ pc2, and the mean luminosity gradient of the exponential component G(a) = -0.20 = -0.18 .
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1963
- DOI:
- 10.1086/147696
- Bibcode:
- 1963ApJ...138..934D