Browsing by Subject "Photometry"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Open Access
    High-speed photometry of SDSS J013701.06 − 091234.9
    (2004) Pretorius, M L; Woudt, P A; Warner, B; Bolt, G; Patterson, J; Armstrong, E
    We present high speed photometry of the Sloan Digital Sky Survey cataclysmic variable SDSS J013701.06-091234.9 in quiescence and during its 2003 December superoutburst. The orbital modulation at 79.71pm0.01 min is double humped; the superhump period is 81.702pm0.007 min. Towards the end of the outburst late superhumps with a period of 81.29pm0.01 min were observed. We argue that this is a system of very low mass transfer rate, and that it probably has a long outburst interval.
  • Thumbnail Image
    Item
    Open Access
    Inhomogeneities in molecular layers of Mira atmospheres
    (2011) Wittkowski, M; Boboltz, D A; Ireland, M; Karovicova, I; Ohnaka, K; Scholz, M; van Wyk, F; Whitelock, P; Wood, P R; Zijlstra, A A
    Aims. We investigate the structure and shape of the photospheric and molecular layers of the atmospheres of four Mira variables.
  • Thumbnail Image
    Item
    Open Access
    The void galaxy survey: photometry, structure and identity of void galaxies
    (2017) Beygu, B; Peletier, R F; Hulst, J M van der; Jarrett, T H; Kreckel, K; Weygaert, R van de; van Gorkom, J H; Aragon-Calvo, M A
    We analyse photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6 μm and 4.5 μm Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the Sloan Digital Sky Survey Data Release 7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from MB = -15.5 to -20, while at the 3.6 μm band their magnitudes range from M3.6 = -18 to -24. Their B-[3.6] colour and structural parameters indicate these are star-forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3 × 1010 M⊙. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sérsic indices are nearly all smaller than n = 2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.
  • Thumbnail Image
    Item
    Open Access
    Unveiling the nature of INTEGRAL objects through optical spectroscopy: III. Observations of seven southern sources
    (2006) Masetti, N; Pretorius, M L; Palazzi, E; Bassani, L; Bazzano, A; Bird, A J; Charles, P A; Dean, A J; Malizia, A; Nkundabakura, P; Stephen, J B; Ubertini, P
    . The detection, thanks to the