Browsing by Author "McCall, ML"

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    Discovery of a huge young stellar object interaction region in Camelopardalis
    (University of Chicago Press, 2004) McCall, ML; Buta, RJ; Foster, TJ; Huchtmeier, W; Huchra, J; York University - Canada; University of Alabama Tuscaloosa; University of Alberta; Max Planck Society; Harvard University; Smithsonian Astrophysical Observatory; Smithsonian Institution
    During the course of a wide-field VI survey of galaxies in the IC 342/Maffei Group, a large nebula, which looks like an inclined disk with a jetlike plume emerging from it, was discovered in Camelopardalis. The object is most prominent in I. The predominating disk component is 6.'8 across, which corresponds to 4.0 +/- 1.6 pc at the estimated distance of 2.0 +/- 0.8 kpc (the Perseus Arm). The plume extends 3.'8 ( 2.2 pc) outward from the core along a direction that is about 20degrees from the minor axis of the disk. The disk lies along the edge of a filament of dust and molecular gas in the Milky Way. The plume points toward the core of the filament. No large-scale emission is seen at Halpha, and the nebula is invisible in Two Micron All Sky Survey (2MASS) images. About 30" from the center of the disk is IRAS 04261+6339, which is a pair of unresolved Halpha sources whose IRAS colors and spectra reveal them to be young stellar objects (YSOs). The northern of the two exhibits a near-infrared tail, which is 15" (0.15 pc) long in H and directed 66degrees away from the plume. Although the stars are exposed, as in Class II YSOs, the spectral energy distribution of the pair rises beyond 2 mum, typical of Class I systems. It appears that they are transitional YSOs, with characteristics similar to those of Holoea (IRAS 05327+ 3404). The total brightness of the plume plus disk exceeds that of the stars by 1.6 mag in I, yet the V - I color is bluer by only 0.50 mag. Thus, the nebula cannot be a consequence of reflection, even allowing for differential extinction. It is tentatively identified as a remnant of an outflow from a binary YSO, glowing from the photoluminescence of silicon nanoparticles.
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    Discovery of a second companion of Dwingeloo 1
    (American Institute of Physics, 1997-03) McCall, ML; Buta, RJ; University of Alabama Tuscaloosa
    Deep near-infrared CCD imaging of the field of the recently discovered nearby galaxies Dwingeloo 1 and 2 has revealed a third, previously unknown galaxy which is most likely a second physical companion of Dwingeloo 1. Only 9'.2 to the southwest of Dwingeloo 1 is a diffuse featureless oval with a diameter of 1'.9 in I. Isophotes are oriented nearly east-west and within 30 degrees of the direction of Dwingeloo 1. Neutral hydrogen studies have failed to reveal a source at this position, and no H alpha emission is evident. Thus, the object is probably a dwarf spheroidal companion of Dwingeloo 1, although there is a small possibility that it is a quiescent gas-rich dwarf with a velocity low enough that its signal is confused with emission from the Milky Way. The galaxy is almost certainly a member of the IC 342-Maffei 1 group, thereby placing it 3+/-1 Mpc away. (C) 1997 American Astronomical Society.
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    The extinction and distance of Maffei 1
    (University of Chicago Press, 2003) Fingerhut, RL; McCall, ML; De Robertis, M; Kingsburgh, RL; Komljenovic, M; Lee, H; Buta, RJ; York University - Canada; University of Alabama Tuscaloosa
    We have obtained low- and high-resolution spectra of the core of the highly reddened elliptical galaxy Maffei 1. From these data, we have obtained the first measurement of the Mg-2 index and have measured the velocity dispersion and radial velocity with improved accuracy. To evaluate the extinction, a correlation between the Mg-2 index and effective V-I color has been established for elliptical galaxies. Using a new method for correcting for effective wavelength shifts, the V-I color excess reveals that the optical depth of Galactic dust at 1 mum is 1.69 +/- 0.07. Thus, A(V) = 4.67 +/- 0.19 mag, which is lower by 0.4 mag than previously thought. To establish the distance, the fundamental plane for elliptical galaxies has been constructed in I. The velocity dispersion of Maffei 1, measured to be 186.8 +/- 7.4 km s(-1), in combination with modern wide. field photometry in I, leads to a distance of 2.92 +/- 0.37 Mpc. The D-n-sigma relation, which is independently calibrated, gives 3.08 +/- 0.85 and 3.23 +/- 0.67 Mpc from photometry in B and K', respectively. The weighted mean of the three estimates is 3.01 +/- 0.30 Mpc, which is lower than distances judged with reference to M32 and the bulge of M31 from the brightest stars seen at K'. Since the luminosity of asymptotic giant branch stars at K' is strongly dependent on age, the lower distance suggests that the last epoch of star formation in Maffei 1 occurred farther in the past than in these other systems. The distance and luminosity make Maffei 1 the nearest giant elliptical galaxy. In the absence of extinction, the galaxy would be among the brightest in the sky and would have an apparent size 2/3 that of the full Moon. The radial velocity of Maffei 1 is + 66.4 +/- 5.0 km s(-1), significantly higher than the accepted value of -10 km s(-1). The Hubble distance corresponding to the mean velocity of Maffei 1, Maffei 2, and IC 342 is 3.5 Mpc. Thus, it is unlikely that Maffei 1 has had any influence on Local Group dynamics.
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    The IC 342/Maffei Group revealed
    (IOP Publishing, 1999) Buta, RJ; McCall, ML; York University - Canada; University of Alabama Tuscaloosa
    Deep wide-field CCD images in the optical and near-infrared have been acquired for 14 of the 16 known or suspected members of the IC 342/Maffei Group of galaxies, one of the closest groups to the Milky Way, and probably the closest group to M31. Because of their low Galactic latitude, all galaxies are heavily extinguished, and myriads of foreground stars are superimposed. A sophisticated algorithm built around DAOPHOT has been developed which successfully removes the foreground stars, making possible comprehensive morphological and photometric studies. The cleaned near-infrared images reveal the true morphology and extent of many of the galaxies for the first time, three of which are among the largest in the northern sky. Besides surface brightness profiles, precise total magnitudes and colors have been measured. Many of the results represent substantial revisions to previous estimates. The data will make possible new determinations of the distances and masses of the galaxies, which are crucial for evaluating the impact the group may have had upon the dynamical evolution of the Local Group.
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    Maffei 1 with the Hubble Space Telescope
    (University of Chicago Press, 2003-03) Buta, R; McCall, ML; University of Alabama Tuscaloosa; York University - Canada
    High-resolution R, I, and H images of the center of Maffei 1, the nearest normal giant elliptical galaxy (M-V(0) = -20.9), have been acquired with the Hubble Space Telescope. At its distance of 3.0 Mpc, 1 pixel in the Planetary Camera field covers only 0.66 pc. The observations reveal that Maffei 1 is a "core type" elliptical galaxy, which is typical of intermediate to massive elliptical galaxies. A source of H emission has been discovered in the center. It is barely resolved, with a size of 1.2 pc and an ionized gas mass of only 29 M-circle dot. Dust is very prominent west of the center in a complex irregular pattern. The correlation between the reddening and the defficiency in surface brightness reveals that the dust is most likely Galactic in origin and that the reddening law along the line of sight is typical of that for the diffuse interstellar medium. For the first time, globular clusters have been detected. Twenty field sources show slightly or significantly extended profiles relative to foreground stars. In I the absolute magnitude of the brightest is -9.6, which is comparable to that of M3 in the Milky Way. The spread in R-I colors, as well the mean color, of these objects is greater than that found for Galactic globular clusters, which may be due in part to a metallicity difference compared with Galactic globular clusters and in part to the variable Galactic extinction across the Wide Field Planetary Camera 2 field. Fits of integrated analytic King models to three of the brighter candidates give core radii and concentration parameters that are comparable to those of Galactic globular clusters.