We present a comparison of late-type galaxies (Sa and later) in intermediate-redshift clusters and in the field using images from the Advanced Camera for Surveys aboard the Hubble Space Telescope. Cluster and field galaxies are selected by matching photometric and spectroscopic catalogs of four cluster fields: Cl 0152-1357, Cl 1056-0337 (MS 1054), Cl 1604+4304, and Cl 1604+4321. Concentration, asymmetry, and clumpiness parameters are calculated for each galaxy in blue (F606W or F625W) and red (F775W or F814W) filters. Galaxy half-light radii, disk scale lengths, color gradients, and overall color are compared.
We present a quantitative morphological analysis of 187 galaxies in a region covering the central 0.28deg^2^ of the Coma Cluster. Structural parameters from the best-fitting Sersic r^1/n^ bulge plus, where appropriate, exponential disk model, are tabulated here. This sample is complete down to a magnitude of R=17mag. By examining the recent compilation by Edwards et al. (2002ApJ...567..178E) of galaxy redshifts in the direction of Coma, we find that 163 of the 187 galaxies are Coma Cluster members and that the rest are foreground and background objects. For the Coma Cluster members, we have studied differences in the structural and kinematic properties between early- and late-type galaxies and between the dwarf and giant galaxies.
This paper presents morphological type, membership and U-V colour for a sample of galaxies in the Coma cluster direction, complete down to M_B_=-15.00mag and extending down to M_B_=-14.25mag. We have examined 1155 objects from the GMP 1983 catalogue on B and V images of the CFH12K camera, and obtained the Hubble type in most cases. Coma cluster membership for 473 galaxies has been derived using morphology, apparent size and surface brightness, and, afterward, redshift. The comparison between morphology- and redshift- memberships and of luminosity functions derived from this morphologically-selected sample, or using statistical members or spectroscopic members, both show that the morphological membership provided here can be trusted. For the first time the morphological classification of Coma galaxies reaches faint enough magnitudes to observe the whole magnitude range of the giant types, E, S0 and spiral stages. The data presented in this paper makes our sample the richest environment where membership and morphology for complete samples down to faint magnitudes (M_B_~-15mag) are available, hence enlarging the baseline of environmental studies.
We present 263 optical and near-infrared (NIR) images for 42 1s and 48 Seyfert 2s, selected from the Extended 12{mu}m Galaxy Sample. Elliptically averaged profiles are derived from the images, and isophotal radii and magnitudes are calculated from these. We also report virtual aperture photometry that, judging from comparison with previous work, is accurate to roughly 0.05 mag in the optical, and 0.07 mag in the NIR. Our B-band isophotal magnitude and radii, obtained from ellipse fitting, are in good agreement with those of Third Reference Catalogue of Bright Galaxies. When compared with the B band, V, I, J, and K isophotal diameters show that the colors in the outer regions of Seyfert galaxies are consistent with the colors of normal spirals. Differences in the integrated isophotal colors and comparison with a simple model show that the active nucleus+bulge are stronger and redder in the NIR than in the optical. Finally, roughly estimated Seyfert disk surface brightnesses are significantly brighter in B and K than those in normal spirals of similar morphological type.
Most luminous SPIRITS IR transients follow-up obs.
Short Name:
J/ApJ/886/40
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a systematic study of the most luminous (MIR [Vega magnitudes] brighter than -14) infrared (IR) transients discovered by the SPitzer InfraRed Intensive Transients Survey (SPIRITS) between 2014 and 2018 in nearby galaxies (D<35Mpc). The sample consists of nine events that span peak IR luminosities of M_[4.5],peak_ between -14 and -18.2, show IR colors between 0.2<([3.6]-[4.5])<3.0, and fade on timescales between 55d<t_fade_<480d. The two reddest events (A_V_>12) show multiple, luminous IR outbursts over several years and have directly detected, massive progenitors in archival imaging. With analyses of extensive, multiwavelength follow-up, we suggest the following possible classifications: five obscured core-collapse supernovae (CCSNe), two erupting massive stars, one luminous red nova, and one intermediate-luminosity red transient. We define a control sample of all optically discovered transients recovered in SPIRITS galaxies and satisfying the same selection criteria. The control sample consists of eight CCSNe and one Type Iax SN. We find that 7 of the 13 CCSNe in the SPIRITS sample have lower bounds on their extinction of 2<A_V_<8. We estimate a nominal fraction of CCSNe in nearby galaxies that are missed by optical surveys as high as 38.5_-21.9_^+26.0^% (90% confidence). This study suggests that a significant fraction of CCSNe may be heavily obscured by dust and therefore undercounted in the census of nearby CCSNe from optical searches.
The analysis of Proxima Centauri's radial velocities recently led Anglada-Escude et al. to claim the presence of a low-mass planet orbiting the Sun's nearest star once every 11.2 days. Although the a priori probability that Proxima b transits its parent star is just 1.5%, the potential impact of such a discovery would be considerable. Independent of recent radial velocity efforts, we observed Proxima Centauri for 12.5 days in 2014 and 31 days in 2015 with the Microwave and Oscillations of Stars space telescope. We report here that we cannot make a compelling case that Proxima b transits in our precise photometric time series. Imposing an informative prior on the period and phase, we do detect a candidate signal with the expected depth. However, perturbing the phase prior across 100 evenly spaced intervals reveals one strong false positive and one weaker instance. We estimate a false-positive rate of at least a few percent and a much higher false-negative rate of 20%-40%, likely caused by the very high flare rate of Proxima Centauri. Comparing our candidate signal to HATSouth ground-based photometry reveals that the signal is somewhat, but not conclusively, disfavored (1{sigma}-2{sigma}), leading us to argue that the signal is most likely spurious. We expect that infrared photometric follow-up could more conclusively test the existence of this candidate signal, owing to the suppression of flare activity and the impressive infrared brightness of the parent star.
Table 1 lists SNe discovered by the Mount Stromlo Abell Cluster Supernova Search. The SNIa? were classified through the goodness of fit of the template light curves and hence could be SNe of another type that have been misclassified. Those SNe designated nIa were deemed not to be SNIa through the template fits and were not investigated further. Table 3 contains Maximum light magnitudes, {Delta}m15 values and distances derived from the template light curve fitting technique for those SNe from the Mount Stromlo Abell Cluster Supernova Search deemed to be SNIa, as well as those from Phillips (1999AJ....118.1766P) The subdirectory "comp" contains the files with calibrated magnitudes for the local standard stars found in the field of each of the supernovae from the Mount Stromlo Abell Cluster Supernova Search. The numbering of these stars corresponds to that found in the finding charts of each of these fields. These are found online at EDP Sciences. For each local standard, their Cousins B, V, R and I magnitudes are given, as is the error in the magnitude estimate. The subdirectory "flux" contains the files with calibrated fluxes for the supernovae discovered in the Mount Stromlo Abell Cluster Supernova Search. For each supernova, the MACHO VM, RM magnitudes and Cousins B, V, R and I fluxes are given (when available), as are the errors in the derived fluxes. One unit flux is equivalent to 25th magnitude. The subdirectory "mag" contains the files with calibrated magnitudes for the supernovae discovered in the Mount Stromlo Abell Cluster Supernova Search. For each supernova, the MACHO VM, RM magnitudes and Cousins B, V, R and I magnitudes are given (when available), as is the upper and lower errors in the derived magnitudes.
This paper is partly a review of the history of the making of the Mount Wilson Catalogue of Photographic Magnitudes in Selected Areas 1-139 (hereafter the MWC), begun in 1909 and completed in 1930, and it is partly the presentation of new photometric results concerning it. Photoelectric photometry of 435 stars in the 11 Selected Areas of SA 28, 29, 45, 55, 57, 71, 82, 94, 106, 107, and 118 of the MWC is given. The data are used to derive magnitude corrections to the MWC for these areas. Ten of the areas are in the Galactic meridional plane (Galactic longitudes of 0{deg} and 180{deg}). These are the same areas used by Becker in his Basel program of star counts for the study of Galactic structure.
We present first results from a spectroscopic survey designed to examine the metallicity and kinematics of individual red giant branch stars in the outer halo of the Andromeda spiral galaxy (M31). This study is based on multislit spectroscopy with the Keck II 10m telescope and Low Resolution Imaging Spectrograph of the Ca II near-infrared triplet in 99 M31 halo candidates in a field at R=19kpc on the southeast minor axis with brightnesses from 20<I<22.