Halo Of NGC Research Articles

The Im/dE,N mixed morphology dwarf ESO 359-G29 as a probe of a massive halo in NGC 1532

A low surface brightness dwarf, ESO 359-G29, in the neighborhood of the NGC 1532/31 pair, has the morphology of an early-type dE,N/dS0,N nucleated dwarf in yellow and red wavelengths, but shows an Sm or Im late-type morphology in the blue. This mixed morphology is similar to that of the prototype example NGC 4286, companion to NGC 4278. VLA observations of H I, however, show that ESO 359-G29 has a typical dwarf hydrogen content unlike NGC 4286 which is hydrogen depleted. The velocity distribution in NGC 1532 has also been determined from VLA observations of H I. At a distance of 64 kpc from the galaxy, the rotational velocity is 250 km s^-1^, and it is still slowly increasing with distance. The unique geometry and relative motion of the ESO 356-G29 and NGC 1532 configuration suggest that ESO 359-G29 is in a polar orbit of NGC 1532 at a radius of 83 kpc and a velocity of 300 km s^-1^. From these velocities, we derive a total mass of NGC 1532 of 1.7 x 10^12^ M_sun_. The halo radius, although uncertain, is probably not larger than 70 kpc. The disk component contains less than 10% of the total mass and its mass-to-light ratio is in range of 2.5-7. The mass-to- light ratio of the halo material is greater than 80.

An unambiguous observation of the radial expansion of the faint giant halo of the planetary nebula NGC 6826

Spatially resolved observations at high spectral resolution of the [O III] 5007-A line profiles from the faint, giant halo of the planetary nebula NGC 6826 have been obtained with the Manchester echelle spectrometer combined with the Isaac Newton Telescope. The observed profiles were fitted with single Gaussian line profiles. When the widths of the Gaussian profiles are plotted as a function of radius from the centre of the halo of NGC 6826, a trend to smaller widths at higher radii is found, as expected for a radially expanding halo.

Echelle measurements of the electron temperature of the giant halo of the planetary nebula NGC 6543

Observations with the Manchester echelle spectrometer, of spatially resolved profiles of the Hα, [NII] and [OIII] lines from a bright knot in the halo of NGC 6543 yield an electron temperature of T e =8860±1000 K. This seemingly contradicts a previous measurement of T e =14700±850 K from the [OIII] (5007A/4363A) line intensity ratio for exactly the same area of the halo which is 6000 K higher than that given for the nebular core by the same line ratio method. A model in which flows of mass-loaded stellar wind form bow shocks around halo clumps is presented in an attempt to explain this apparent discrepancy in the values of T e for the halo of NGC 6543 that is found between the profile and ratio methods.

The nature of bright giants in the halo of NGC 253 and implications for the distance scale

The 3.6 m Canada-France-Hawaii Telescope has been used to obtain dep V and I CCD images of a field in the halo of NGC 253. A larger number of stellar objects, far in excess of that expected from background galaxies and foreground stars, have been detected fainter than I = 22.5 and V = 24.0, and these are identified as bright giants in the halo of NGC 253. The luminosities of the brightest objects in the field are similar to those of asymptotic giant branch stars in Galactic globular clusters. If these luminous stars are assumed to be similar to the brightest giants in the outer halo of M31, then the distance modulus of NGC 253 is equal to or less than 26.8. This is slightly lower than the canonical value derived from other distance indicators. 32 refs.

Some features of the galactic halo in NGC 891

Main results of the galactic halo in NGC 891 newly obtained from the Palomar (U′, J, F)-WSRT (21,6 cm) observation (both smoothed to 20″×20″ resolution) and some of the possible explanations have been summarized.

Faint photometry of edge-on spiral galaxies - A search for massive halos

view Abstract Citations (37) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Faint photometry of edge-on spiral galaxies : a search for massive halos. Skrutskie, M. F. ; Shure, M. A. ; Beckwith, S. Abstract Upper limits have been set to the luminosity from the massive halos of three late-type edge-on spiral galaxies: NGC 2683 (Sb), NGC 4244 (Scd), and NGC 5907 (Sc). The limits resulted from simultaneous photometry in the visual (V) and 2.2-micron (K) photometric bands which is sensitive to both luminosity and color changes along the minor axes of the three galaxies. The mass-to-light ratios for the halo of NGC 5907 are the largest ever recorded: M/L(V) greater than 2000 and M/L(K) greater than 64 in solar units. The results virtually eliminate the possibility that hydrogen-burning stars comprise more than a fraction of the halo masses. Variations of the V-K color along and perpendicular to the disks show no sign of population changes toward redder objects at large galactocentric radii. The nucleus of NGC 5907 contains an unresolved source less than 330 pc in size with a 2.2-micron luminosity of order 5 x 10 to the 9th solar luminosity and may be an example of a starburst galactic nucleus overlooked by visual observations. Publication: The Astrophysical Journal Pub Date: December 1985 DOI: 10.1086/163701 Bibcode: 1985ApJ...299..303S Keywords: Astronomical Photometry; Galactic Radiation; Halos; Spiral Galaxies; Colorimetry; Galactic Nuclei; Luminous Intensity; Mass To Light Ratios; Metallicity; Point Sources; Starburst Galaxies; Astrophysics full text sources ADS | data products SIMBAD (3) NED (3)