17 research outputs found
Direct Measurement of Neutron-Star Recoil in the Oxygen-Rich Supernova Remnant Puppis A
A sequence of three Chandra X-ray Observatory High Resolution Camera images
taken over a span of five years reveals arc-second-scale displacement of RX
J0822-4300, the stellar remnant (presumably a neutron star) near the center of
the Puppis A supernova remnant. We measure its proper motion to be
0.165+/-0.025 arcsec/yr toward the west-southwest. At a distance of 2 kpc, this
corresponds to a transverse space velocity of ~1600 km/s. The space velocity is
consistent with the explosion center inferred from proper motions of the
oxygen-rich optical filaments, and confirms the idea that Puppis A resulted
from an asymmetric explosion accompanied by a kick that imparted roughly
3*10^49 ergs of kinetic energy (some 3 percent of the kinetic energy for a
typical supernova) to the stellar remnant. We discuss constraints on
core-collapse supernova models that have been proposed to explain neutron star
kick velocities
Peculiar motions of the gas at the centre of the barred galaxy UGC 4056
We derive the circular velocity curves of the gaseous and stellar discs of
UGC 4056, a giant barred galaxy with an active galactic nucleus (AGN). We
analyse UGC 4056 using the 2D spectroscopy obtained within the framework of the
Mapping Nearby Galaxies at APO (MaNGA) survey. Using images and the colour
index g-r from the Sloan Digital Sky Survey (SDSS), we determined the tilt of
the galaxy, which allows us to conclude that the galaxy rotates clockwise with
trailing spiral arms. We found that the gas motion at the central part of the
UGC 4056 shows peculiar features. The rotation velocity of the gaseous disc
shows a bump within around three kiloparsecs while the rotation velocity of the
stellar disc falls smoothly to zero with decreasing galactocentric distance. We
demonstrate that the peculiar radial velocities in the central part of the
galaxy may be caused by the inflow of the gas towards the nucleus of the
galaxy. The unusual motion of the gas takes place at the region with the
AGN-like radiation and can be explained by the gas response to the bar
potential.Comment: 11 pages, 10 figures, 1 table, accepted for publication in A&
Properties of galaxies with an offset between the position angles of the major kinematic and photometric axes
We derive the photometric, kinematic, and abundance characteristics of 18 star-forming MaNGA galaxies with fairly regular velocity fields and surface brightness distributions and with a large offset between the measured position angles of the major kinematic and photometric axes, Delta PA greater than or similar to 20 degrees. The aim is to examine if there is any other distinctive characteristic common to these galaxies. We found morphological signs of interaction in some (in 11 out of 18) but not in all galaxies. The observed velocity fields show a large variety; the maps of the isovelocities vary from an hourglass-like appearance to a set of straight lines. The position angles of the major kinematic axes of the stellar and gas rotations are close to each other. The values of the central oxygen abundance, radial abundance gradient, and star formation rate are distributed within the intervals defined by galaxies with small (no) Delta PA of similar mass. Thus, we do not find any specific characteristic common to all galaxies with large Delta PA. Instead, the properties of these galaxies are similar to those of galaxies with small (no) Delta PA. This suggests that either the reason responsible for the large Delta PA does not influence other characteristics or the galaxies with large Delta PA do not share a common origin, they can, instead, originate through different channels
The IMF in Starbursts
The history of the IMF in starburst regions is reviewed. The IMFs are no
longer believed to be top-heavy, although some superstar clusters, whether in
starburst regions or not, could be. General observations of the IMF are
discussed to put the starburst results in perspective. Observed IMF variations
seem to suggest that the IMF varies a little with environment in the sense that
denser and more massive clusters produce more massive stars, and perhaps more
brown dwarfs too, compared to intermediate mass stars.Comment: 8 pages, to be published in ``Starbursts: from 30 Doradus to Lyman
Break Galaxies,'' held at Institute of Astronomy, Cambridge University, UK,
September 6-10, 2004. Kluwer Academic Publishers, edited by Richard de Grijs
and Rosa M. Gonzalez Delgad
Comparison of integrated photometric parameters of extragalactic star formation complexes and open star clusters in the Milky Way
Peculiar motions of the gas at the centre of the barred galaxy UGC 4056
We derive the circular velocity curves of the gaseous and stellar discs of UGC 4056, a giant barred galaxy with an active galactic nucleus (AGN). We analyse UGC 4056 using the 2D spectroscopy obtained within the framework of the Mapping Nearby Galaxies at APO (MaNGA) survey. Using images and the colour index g - r from the Sloan Digital Sky Survey (SDSS), we determined the tilt of the galaxy, which allows us to conclude that the galaxy rotates clockwise with trailing spiral arms. We found that the gas motion at the central part of the UGC 4056 shows peculiar features. The rotation velocity of the gaseous disc shows a bump within around three kiloparsecs while the rotation velocity of the stellar disc falls smoothly to zero with decreasing galactocentric distance. We demonstrate that the peculiar radial velocities in the central part of the galaxy may be caused by the inflow of the gas towards the nucleus of the galaxy. The unusual motion of the gas takes place at the region with the AGN-like radiation and can be explained by the gas response to the bar potential
Age and interstellar absorption in young star-formation regions in the galaxies NGC 1068, NGC 4449, NGC 4490, NGC 4631, and NGC 4656/57 derived from multicolor photometry
Spiral arms in CALIFA galaxies traced by non-circular velocities, abundances and extinctions
We derive maps of the observed velocity of ionized gas, the oxygen abundance and the extinction (Balmer decrement) across the area of the four spiral galaxies NGC 36, NGC 180, NGC 6063 and NGC 7653 from integral field spectroscopy obtained by the Calar Alto Legacy Integral Field Area (CALIFA) survey. We searched for spiral arms through Fourier analysis of the spatial distribution of three tracers (non-circular motion, enhancement of the oxygen abundance and of the extinction) in the discs of our target galaxies. The spiral arms (twoarmed logarithmic spirals in the deprojected map) are shown in each target galaxy for each tracer considered. The pitch angles of the spiral arms in a given galaxy obtained with the three different tracers are close to each other. The enhancement of the oxygen abundance in the spiral arms as compared to the abundance in the interarm regions at a given galactocentric distance is small, within a few per cent. We identified a metallicity gradient in our target galaxies. Both barred galaxies in our sample show flatter gradients than the two galaxies without bars. Galactic inclination, position angle of the major axis and the rotation curve were also obtained for each target galaxy using the Fourier analysis of the two-dimensional velocity map.© 2017 The Author(s).We are very grateful to the referee for his/her constructive comments and recommendations, which significantly improved the article. IAZ, LSP, EKG and AJ acknowledge support within the framework of Sonderforschungsbereich SFB 881 on 'The Milky Way System' (especially via sub-projects A5 and A6). SFB 881 is funded by the German Research Foundation (DFG). IAZ and LSP and thank for the hospitality of the Astronomisches Rechen-Institut at Heidelberg University, where part of this investigation was carried out.
IAZ acknowledges the support of the Volkswagen Foundation under the Trilateral Partnerships grant No. 90411. This study uses data provided by the CALIFA survey (http://califa.caha.es/) and is based on observations collected at the Centro Astronomico Hispano Aleman (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut fur Astronomie and the Instituto de Astrofisica de Andalucia (CSIC). The authors acknowledge the usage of the HyperLeda data base (http://leda.univ-lyon1.fr) and the NASA/IPAC Extragalactic Database (http://ned.ipac.caltech.edu)