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2321. Morphology of spiral galaxies
ID:
ivo://CDS.VizieR/J/ApJS/143/73
Title:
Morphology of spiral galaxies
Short Name:
J/ApJS/143/73
Date:
21 Oct 2021
Publisher:
CDS
Description:
We announce the initial release of data from the Ohio State University (OSU) Bright Spiral Galaxy Survey (OSUBSGS), a BVRJHK imaging survey of a well-defined sample of 205 bright, nearby spiral galaxies. We present H-band morphological classification on the Hubble sequence for the OSU Survey sample. We compare the H-band classification to B-band classification from our own images and from standard galaxy catalogs. Our B-band classifications match well with those of the standard catalogs. On average, galaxies with optical classifications from Sa through Scd appear about one T type earlier in the H band than in the B band, but with large scatter. This result does not support recent claims made in the literature that the optical and near-IR morphologies of spiral galaxies are uncorrelated. We present detailed descriptions of the H-band morphologies of our entire sample, as well as B- and H-band images for a set of 17 galaxies chosen as type examples and BRH color-composite images of six galaxies chosen to demonstrate the range in morphological variation as a function of wavelength.
2322. Morphology of supernova host galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/424/2841
Title:
Morphology of supernova host galaxies
Short Name:
J/MNRAS/424/2841
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents an analysis of core-collapse supernova distributions in isolated and interacting host galaxies, paying close attention to the selection effects involved in conducting host galaxy supernova studies. When taking into account all of the selection effects within our host galaxy sample, we draw the following conclusions. 1. Within interacting, or 'disturbed', systems there is a real, and statistically significant, increase in the fraction of stripped-envelope supernovae in the central regions. A discussion into what may cause this increased fraction, compared to the more common Type IIP supernovae and Type II supernovae without subclassifications, is presented. Selection effects are shown not to drive this result, and so we propose that this study provides direct evidence for a high-mass weighted initial mass function within the central regions of disturbed galaxies. 2. Within 'undisturbed' spiral galaxies the radial distribution of Type Ib and Type Ic supernovae is statistically very different, with the latter showing a more centrally concentrated distribution. This could be driven by metallicity gradients in these undisturbed galaxies, or radial variations in other properties (binarity or stellar rotation) driving envelope loss in progenitor stars. This result is not found in 'disturbed' systems, where the distributions of Type Ib and Ic supernovae are consistent.
2323. Morphology of 70um COSMOS galaxies
ID:
ivo://CDS.VizieR/J/ApJ/721/98
Title:
Morphology of 70um COSMOS galaxies
Short Name:
J/ApJ/721/98
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze the morphological properties of a large sample of 1503 70um selected galaxies in the COSMOS field spanning the redshift range 0.01<z<3.5 with a median redshift of 0.5 and an infrared luminosity range of 10^8^<L_IR_(8-1000um)<10^14^L_{sun}_ with a median luminosity of 10^11.4^L_{sun}_. In general, these galaxies are massive, with a stellar mass range of 10^10^-10^12^M_{sun}_, and luminous, with -25<M_K_<-20. The precise fraction of mergers in any given L_IR_ bin varies by redshift due to sources at z>1 being difficult to classify and subject to the effects of bandpass shifting; therefore, these numbers can only be considered lower limits. At z<1, where the morphological classifications are most robust, major mergers clearly dominate the ULIRG population (~50%-80%) and are important for the LIRG population (~25%-40%). At z>1, the fraction of major mergers is lower, but is at least 30%-40% for ULIRGs. In a comparison of our visual classifications with several automated classification techniques we find general agreement; however, the fraction of identified mergers is underestimated due to automated classification methods being sensitive to only certain timescales of a major merger. The distribution of the U-V color of the galaxies in our sample peaks in the green valley (<U-V>=1.1) with a large spread at bluer and redder colors and with the major mergers peaking more strongly in the green valley than the rest of the morphological classes.
2324. Motions of galaxies in Coma I cloud
ID:
ivo://CDS.VizieR/J/ApJ/743/123
Title:
Motions of galaxies in Coma I cloud
Short Name:
J/ApJ/743/123
Date:
21 Oct 2021
Publisher:
CDS
Description:
We note that nearby galaxies having high negative peculiar velocities are distributed over the sky very inhomogeneously. A part of this anisotropy is caused by the "Local Velocity Anomaly," i.e., by the bulk motion of nearby galaxies away from the Local Void. However, half of the fast-flying objects reside within a small region [RA=11.5h-13.0h, DE=+20{deg}-40{deg}] known as the Coma I cloud. According to Makarov & Karachentsev, this complex contains 8 groups, 5 triplets, 10 pairs, and 83 single galaxies with a total mass of 4.7x10^13^M_{sun}_. We use 122 galaxies in the Coma I region with known distances and radial velocities V_LG_<3000km/s to draw the Hubble relation for them. The Hubble diagram shows a Z-shaped effect of infall with an amplitude of +200km/s on the nearby side and -700km/s on the back side. This phenomenon can be understood as the galaxy infall toward a dark attractor with a mass of ~2x10^14^M_{sun}_ situated at a distance of 15 Mpc from us. The existence of a large void between the Coma and Virgo clusters also probably affects the Hubble flow around the Coma I.
2325. 100-Mpc-scale structures of radio galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/344/283
Title:
100-Mpc-scale structures of radio galaxies
Short Name:
J/MNRAS/344/283
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present unequivocal evidence for a huge (~80x100x100Mp^3^) superstructure at redshift z=0.27 in the three-dimensional distribution of radio galaxies from the Texas-Oxford NVSS Structure 08h region (TONS08) sample, confirming tentative evidence for such a structure from the 7C redshift survey (7CRS). A second, newly discovered superstructure is also found less securely at redshift 0.35 (of dimensions ~100x100x100Mpc^3^). We present full observational details on the TONS08 sample which was constructed to probe structures in the redshift range 0<z<0.5 by matching NVSS sources with objects in APM catalogues to obtain a sample of optically bright (E~R<=19.83), radio-faint (1.4GHz flux density S_1.4_>=3mJy) radio galaxies in the same 25deg^2^ area as part II of the 7CRS.
2326. M31 PHAT star clusters
ID:
ivo://CDS.VizieR/J/A+A/602/A112
Title:
M31 PHAT star clusters
Short Name:
J/A+A/602/A112
Date:
21 Oct 2021
Publisher:
CDS
Description:
This study is the fifth of a series that investigates the degeneracy and stochasticity problems present in the determination of physical parameters such as age, mass, extinction, and metallicity of partially resolved or unresolved star cluster populations in external galaxies when using HST broad-band photometry. In this work we aim to derive parameters of star clusters using models with fixed and free metallicity based on the HST WFC3+ACS photometric system. The method is applied to derive parameters of a subsample of 1363 star clusters in the Andromeda galaxy observed with the HST. Following Paper III (de Meulenaer et al., 2015A&A...574A..66D), we derive the star cluster parameters using a large grid of stochastic models that are compared to the six observed integrated broad-band WFC3+ACS magnitudes of star clusters. We show that the age, mass, and extinction of the M31 star clusters, derived assuming fixed solar metallicity, are in agreement with previous studies. We also demonstrate the ability of the WFC3+ACS photometric system to derive metallicity of star clusters older than ~1 Gyr. We show that the metallicity derived using broad-band photometry of 36 massive M31 star clusters is in good agreement with the metallicity derived using spectroscopy.
2327. M31 PHAT star clusters ages and masses
ID:
ivo://CDS.VizieR/J/ApJ/786/117
Title:
M31 PHAT star clusters ages and masses
Short Name:
J/ApJ/786/117
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present ages and masses for 601 star clusters in M31 from the analysis of the six filter integrated light measurements from near-ultraviolet to near-infrared wavelengths, made as part of the Panchromatic Hubble Andromeda Treasury (PHAT). We derive the ages and masses using a probabilistic technique, which accounts for the effects of stochastic sampling of the stellar initial mass function. Tests on synthetic data show that this method, in conjunction with the exquisite sensitivity of the PHAT observations and their broad wavelength baseline, provides robust age and mass recovery for clusters ranging from ~10^2^ to 2x10^6^ M_{sun}_. We find that the cluster age distribution is consistent with being uniform over the past 100 Myr, which suggests a weak effect of cluster disruption within M31. The age distribution of older (>100 Myr) clusters falls toward old ages, consistent with a power-law decline of index -1, likely from a combination of fading and disruption of the clusters. We find that the mass distribution of the whole sample can be well described by a single power law with a spectral index of -1.9+/-0.1 over the range of 10^3^-3x10^5^ M_{sun}_. However, if we subdivide the sample by galactocentric radius, we find that the age distributions remain unchanged. However, the mass spectral index varies significantly, showing best-fit values between -2.2 and -1.8, with the shallower slope in the highest star formation intensity regions. We explore the robustness of our study to potential systematics and conclude that the cluster mass function may vary with respect to environment.
2328. M51 Planetary Nebula Candidates
ID:
ivo://CDS.VizieR/J/ApJ/582/170
Title:
M51 Planetary Nebula Candidates
Short Name:
J/ApJ/582/170
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of a radial velocity survey of planetary nebulae (PNe) located in the tidal features of the well-known interacting system NGC 5194/95 (M51). We find clear kinematic evidence that M51's northwestern tidal debris consists of two discrete structures that overlap in projection - NGC 5195's own tidal tail and diffuse material stripped from NGC 5194. We compare these kinematic data to a new numerical simulation of the M51 system and show that the data are consistent with the classic "single-passage" model for the encounter, with a parabolic satellite trajectory and a 2:1 mass ratio. We also comment on the spectra of two unusual objects: a high-velocity PN that may be associated with NGC 5194's halo and a possible interloping high-redshift galaxy.
2329. M31 planetary nebulae velocities
ID:
ivo://CDS.VizieR/J/MNRAS/369/97
Title:
M31 planetary nebulae velocities
Short Name:
J/MNRAS/369/97
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present radial velocities for a sample of 721 planetary nebulae in the disc and bulge of M31, measured using the WYFFOS fibre spectrograph on the William Herschel Telescope. Velocities are determined using the [OIII] {lambda}5007 emission line. Rotation and velocity dispersion are measured to a radius of 50arcmin (11.5kpc), the first stellar rotation curve and velocity dispersion profile for M31 to such a radius. Our kinematics are consistent with rotational support at radii well beyond the bulge effective radius of 1.4kpc, although our data beyond a radius of 5kpc are limited. We present tentative evidence for kinematic substructure in the bulge of M31 to be studied fully in a later work. This paper is part of an ongoing project to constrain the total mass, mass distribution and velocity anisotropy of the disc, bulge and halo of M31.
2330. M31 polarization & magnetic structure
ID:
ivo://CDS.VizieR/J/A+A/571/A61
Title:
M31 polarization & magnetic structure
Short Name:
J/A+A/571/A61
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Andromeda Galaxy (M31) is the nearest grand-design spiral galaxy. Thus far, most studies in the radio regime concentrated on the 10kpc ring. The central region of M31 has significantly different properties than the outer parts: The star formation rate is low, and inclination and position angle are largely different from the outer disk. The existing model of the magnetic field in the radial range 6<=r<=14kpc is extended to the innermost part r<=0.5kpc to ultimately achieve a picture of the entire magnetic field in M 31. We combined observations taken with the VLA at 3.6cm and 6.2cm with data from the Effelsberg 100-m telescope to fill the missing spacings of the synthesis data. The resulting polarization maps were averaged in sectors to analyse the azimuthal behaviour of the polarized intensity (PI), rotation measure (RM), and apparent pitch angle ({phi}_obs_). We developed a simplified 3D model for the magnetic field in the central region to explain the azimuthal behaviour of the three observables. Our 3D model of a quadrupolar or dipolar dynamo field can explain the observed patterns in PI, RM, and {phi}_obs_, while a 2D configuration is not sufficient to explain the azimuthal behaviour. In addition and independent of our model, the RM pattern shows that the spiral magnetic field in the inner 0.5kpc points outward, which is opposite to that in the outer disk, and has a pitch angle of =~33{deg}, which is much larger than that of 8{deg}-19{deg} in the outer disk. The physical conditions in the central region differ significantly from those in the 10kpc ring. In addition, the orientation of this region with respect to the outer disk is completely different. The opposite magnetic field directions suggest that the central region is decoupled from the outer disk, and we propose that an independent dynamo is active in the central region.