University of Alabama Repository :: Browsing by Author "Buta, RJ"

Browsing by Author "Buta, RJ"

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CORRECTIONS AND ADDITIONS TO THE 3RD REFERENCE CATALOG OF BRIGHT GALAXIES
(American Institute of Physics, 1994-12) Corwin, HG; Buta, RJ; Devaucouleurs, G; University of Alabama Tuscaloosa; University of Texas System; University of Texas Austin
Lists of corrections and additions to the Third Reference Catalogue of Bright Galaxies (RC3) are given. The corrected version of the catalogue (RC3.9b), dated April 1994, is currently available through the national data centers.
DISCOVERY OF 2 LIKELY DWARF COMPANIONS OF MAFFEI-1
(American Institute of Physics, 1995-06) Mccall, ML; Buta, RJ; University of Alabama Tuscaloosa; York University - Canada
Deep wide-field CCD images have revealed two likely late-type galaxies about 20 arcmin away from Maffei 1. The brighter object may be a spiral, but the fainter is probably a dwarf irregular galaxy. The two objects are probably members of the IC 342-Maffei group of galaxies. © 1995 American Astronomical Society.
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.
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.
THE DISTANCE TO THE HERCULES SUPERCLUSTER .1. BASIC DATA FOR 220 GALAXIES IN CGCG FIELD-108
(IOP Publishing, 1986-10) Buta, RJ; Corwin, HG; University of Texas System; University of Texas Austin; University of Alabama Tuscaloosa
THE DISTANCE TO THE HERCULES SUPERCLUSTER .2. APPLICATION OF TERTIARY INDICATORS AND AN ESTIMATE OF THE HUBBLE CONSTANT
(University of Chicago Press, 1986-10) Buta, RJ; Corwin, HG; University of Texas System; University of Texas Austin; University of Alabama Tuscaloosa
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.
THE GALACTIC EXTINCTION TOWARDS MAFFEI-1
(Blackwell, 1983-11-01) Buta, RJ; Mccall, ML; University of Texas System; University of Texas Austin; Australian National University; University of Alabama Tuscaloosa
A Hubble Space Telescope study of star formation in the inner resonance ring of NGC 3081
(IOP Publishing, 2004) Buta, RJ; Byrd, GG; Freeman, T; University of Alabama Tuscaloosa
We present Hubble Space Telescope Wide Field Planetary Camera 2 images of the inner regions of NGC 3081, an absolute magnitude M-B = - 20.0 early-type barred spiral having four well-defined resonance rings: a nuclear ring, an inner ring, an outer R-1 ring, and an outer R-2' pseudoring. Here we focus on a photometric study of the inner ring, a feature likely associated with an inner 4: 1 resonance near the ends of the bar. The ring is notable for its high contrast and sharp definition, which is due to a significant degree of active star formation. The ring is also notable for its significant intrinsic elongation and parallel alignment with the bar. These characteristics influence the way star-forming sites are distributed around the ring. The ring is lined by numerous blue sources, many of which appear to be slightly diffuse compared with the stellar point-spread function. These blue sources are strongly concentrated within +/-60degrees of the bar axis and follow the Halpha distribution well. The blue sources are much larger than typical Galactic open or globular clusters and may represent young massive clusters like the "populous clusters'' of the LMC and objects seen previously mainly in intermediate- to late-type spiral galaxies. We also present an analysis of the integrated light of the inner ring, to deduce information on its star formation history. A profile analysis is used to separate the ring from the background old disk starlight. High-resolution Fourier analysis is used to search for wavelength-dependent phase shifts along the ring to determine if star-forming sites stay in the ring as they age. The results give an intriguing picture of a galaxy in an advanced evolutionary state where periodic orbits are clearly manifested in the morphology.
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.
IDENTIFICATION OF A NEBULOUS BLUE OBJECT NEAR MAFFEI-1
(Astronomical Society of the Pacific, 1980-10) Buta, RJ; Mccall, ML; Uomoto, AK; University of Texas System; University of Texas Austin; University of Alabama Tuscaloosa
The inner resonance ring of NGC 3081. II. Star formation, bar strength, disk surface mass density, and mass-to-light ratio
(University of Chicago Press, 2006-03) Byrd, GG; Freeman, T; Buta, RJ; University of Alabama Tuscaloosa
We complement our Hubble Space Telescope (HST) observations of the inner ring of the galaxy NGC 3081 using an analytical approach and n-body simulations. We find that a gas cloud inner (r) ring forms under a rotating bar perturbation with very strong azimuthal cloud crowding where the ring crosses the bar major axis. Thus, star formation results near to and "downstream'' of the major axis. From the dust distribution and radial velocities, the disk rotates counterclockwise (CCW) on the sky like the bar pattern speed. We explain the observed CCW color asymmetry crossing the major axis as due to the increasing age of stellar associations inside the r ring major axis. These move faster than the pattern speed. The exterior point of the r ring at the bar major axis has an orbital rate equal to the pattern speed. We show how the perturbation strength can be estimated from the ring shapes and relative spacing over the inner through outer ring regions. The bar strength ( maximum tangential/radial force) appears to be constant from 6 to 15 kpc. We derive how the perturbation, the fractional long wavelength m 2 intensity, and the rotation curve can be used to calculate the disk surface mass density versus radius. The disk surface density at 7 kpc is 13 M-circle dot pc(-2) rising to 19 at 13 kpc. The latter is insufficient by a factor of seven to generate the observed rotation curve, implying halo domination. The surface density may have been reduced at 7 kpc due to inner ring gas cloud scattering. The surface density plus the observed surface brightness gives a disk mass-to-light (M/L) ratio which increases from 7 kpc through 13 kpc, contradicting the usual assumption in bar strength calculations. The simulation ring lifetime of several billion years is consistent with our similar to 400 Myr HST estimates. With a sufficiently high gas cloud surface mass density, our simulations form gas cloud "associations'' near the ends of the bar as observed. Too high a density destroys the ring.
LIGHT VARIATIONS OF NONRADIAL PULSATORS - THEORY AND APPLICATION TO THE LINE-PROFILE VARIABLE 53-PERSEI
(University of Chicago Press, 1979-08) Buta, RJ; Smith, MA; University of Texas System; University of Texas Austin; University of Alabama Tuscaloosa
Neutral hydrogen in the ringed barred galaxies NGC 1433 and NGC 6300
(University of Chicago Press, 1996-04) Ryder, SD; Buta, RJ; Toledo, H; Shukla, H; StaveleySmith, L; Walsh, W; Commonwealth Scientific & Industrial Research Organisation (CSIRO); University of New South Wales Sydney; University of Alabama Tuscaloosa
We have made observations of the H I in the southern ringed barred spiral galaxies NGC 1433 and NGC 6300 with the Australia Telescope Compact Array (ATCA), the main goal being to test the resonance theory for the origin of these rings. NGC 1433 is the prototypical ringed barred spiral and displays distinct H I counterparts to its nuclear ring, inner ring, outer pseudoring, and plumelike features. The L(4) and L(5) regions at corotation, as well as the bar itself, are relatively devoid of neutral atomic hydrogen. We use the Tully-Fisher relation to argue that the mean inclination of the disk of NGC 1433 is closer to 33 degrees than to 20 degrees, meaning that its outer pseudoring is intrinsically almost circular, while the inner ring is rather more elongated than the average (based on results from the Catalog of Southern Ringed Galaxies). Strong radio continuum emission is localized to the nucleus and the ends of the bar in NGC 1433, and we place an upper limit on the 1.38 GHz flux of the Type II SN 1985P a decade after the explosion, By associating the inner ring of NGC 1433 with the inner second harmonic resonance, and its outer pseudoring with the outer Lindblad resonance, we are able to infer a bar pattern speed for NGC 1433 of 26 +/- 5 km s(-1) kpc(-1). By way of contrast, NGC 6300 possesses a much more extended H I disk than NGC 1433, despite having a similar morphological type. There is a gas ring underlying the inner pseudoring, but it is both broader and slightly larger in diameter than the optical feature. The outer H I envelope has a 20 degrees kinematic warp as well. as a short tail, even though there are no nearby candidates for a recent interaction with NGC 6300. The noncircular motions inferred from optical emission-line spectra do not appear to extend beyond the bar region of NGC 6300. Barely 10% of the 1.38 GHz radio continuum emission in NGC 6300 originates in the type 2 Seyfert nucleus, with the rest coming from a disklike component internal to the ring. By again linking an inner ring feature to the inner second harmonic resonance, we derive a bar pattern speed for NGC 6300 of 27 +/- 8 kM s(-1) kpc(-1), but in this case, neither the outer pseudoring nor the nuclear ring predicted by the resonance ring theory can be identified in NGC 6300. Although it may be the case that the ring in NGC 6300 is not related to a resonance with the bar at all, we postulate instead that NGC 6300 is merely a less well developed example of a resonance ring galaxy than is NGC 1433.
NONRADIAL MODE-IDENTIFICATION OF 53 PERSEI DURING LATE 1977 AND 1978
(University of Chicago Press, 1979-09) Smith, MA; Buta, RJ; University of Texas System; University of Texas Austin; University of Alabama Tuscaloosa
An optical and H I study of NGC 5850: Victim of a high-speed encounter?
(IOP Publishing, 1998) Higdon, JL; Buta, RJ; Purcell, GB; Commonwealth Scientific & Industrial Research Organisation (CSIRO); University of Alabama Tuscaloosa
We present optical CCD surface photometry and VLA H I observations of NGC 5850, one of the largest and brightest barred spirals of the inner ring variety in the sky. The broadband images reveal numerous morphological peculiarities, particularly in the spiral arms. Structural asymmetries are more obvious in H I, the most pronounced being a large-scale displacement of gas to the west and northwest of the nucleus. Most of the (3.3 +/- 0.1) x 10(9) M-circle dot of atomic hydrogen is concentrated in the prominent optical ring and faint spiral arms, with very low H I surface densities (Sigma(HI)) in the bulge and interarm regions. We detect approximately 2 x 10(7) M-circle dot of H I in the southwestern half of the nuclear ring. The H I surface density drops rapidly outside the arms, and we find no evidence for either large-scale tidal features or an extended gas disk above 0.05 M-circle dot pc(-2) (3 sigma). Overall, the intensity-weighted H I velocity field appears fairly regular, yet still shows clear deviations from circular rotation that we attribute to a warped oval disk and streaming motions across the arms. Radio continuum emission at 20 cm is dominated by a faint bulge component that peaks at the optical nucleus. The spiral arms are not detected. The absence of extended X-ray emission throughout the NGC 5846 group and the close similarity between NGC 5850's optical and H I morphologies argue against ram pressure stripping through a dense intergalactic medium as the cause of the galaxy's peculiar morphology. We attribute it instead to a high-speed encounter with the massive elliptical galaxy NGC 5846. We identify the peculiar spiral arms as a disrupted outer pseudoring. Star formation in NGC 5850 has not been enhanced relative to other intermediate field spirals, nor have significant gas masses been transported to the nucleus. This may be attributed to the recent (less than or similar to 200 Myr) nature of the interaction.
The ringed spiral galaxy NGC 4622. I. Photometry, kinematics, and the case for two strong leading outer spiral arms
(IOP Publishing, 2003-02) Buta, RJ; Byrd, GG; Freeman, T; University of Alabama Tuscaloosa
The intriguing nearly face-on southern ringed spiral galaxy NGC 4622, the first galaxy definitively shown to have leading spiral structure, is revisited in this paper with new images from the Hubble Space Telescopes (HST) WFPC2, together with ground-based optical and near-IR imaging, and a Fabry-Perot Halpha velocity field. The data provide new information on the disk/bulge/halo mix, rotation curve, star formation in the galaxy, and the sense of winding of its prominent spiral arms. Previously, we suggested that the weaker, inner single arm most likely has the leading sense, based on a numerical simulation. Now, taking advantage of HST resolution and using de Vaucouleurs standard extinction and reddening technique to determine the near side of the galaxy's slightly tilted disk, we come to the more surprising conclusion that the two strong outer arms have the leading sense. We suggest that this highly unusual configuration may be the result of a past minor merger or mild tidal encounter. Possible evidence for a minor merger is found in a short, central dust lane, although this is purely circumstantial and an unrelated interaction with a different companion could also be relevant. The leading arms may be allowed to persist because NGC 4622 is dark halo dominated (i.e., not maximum disk in the inner regions) and displays a significantly rising rotation curve. The new HST observations also reveal a rich globular cluster system in the galaxy. The mean color of these clusters is (V-I)(0) = 1.04, and the specific frequency is 3.4 +/- 0.6. The luminosity function of these clusters confirms the membership of NGC 4622 in the Centaurus Cluster.

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