- ID:
- ivo://CDS.VizieR/J/A+A/627/A174
- Title:
- Early light curve of SN 2013gy
- Short Name:
- J/A+A/627/A174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an early-phase g-band light curve and visual-wavelength spectra of the normal Type Ia supernova (SN) 2013gy. The light curve is constructed by determining the appropriate S-corrections to transform KAIT natural-system B- and V-band photometry and Carnegie Supernova Project natural-system g-band photometry to the Pan-STARRS1 g-band natural photometric system. A Markov chain Monte Carlo calculation provides a best-fit single power-law function to the first ten epochs of photometry described by an exponent of 2.16^+0.06^_0.06_ and a time of first light of MJD 56629.4^+0.1^_0.1_, which is 1.93^+0.12^_0.13_ days (i.e., <48hr) before the discovery date (2013 December 4.84 UT) and -19.10^+0.12^_0.13_ days before the time of B-band maximum (MJD 56648.50.1). The estimate of the time of first light is consistent with the explosion time inferred from the evolution of the SiII 6355 Doppler velocity. Furthermore, discovery photometry and previous nondetection limits enable us to constrain the companion radius down to Rc<=4R_{sun}_. In addition to our early-time constraints, we used a deep +235 day nebular-phase spectrum from Magellan/IMACS to place a stripped H-mass limit of <0.018M_{sun}_. Combined, these limits effectively rule out H-rich nondegenerate companions.
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- ID:
- ivo://CDS.VizieR/J/other/Obs/136.168
- Title:
- Early observations of M13 variables
- Short Name:
- J/other/Obs/136.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 1900 E.E. Barnard published 37 visual observations of Variable 2 (V2) in the globular cluster M13 made in 1899 and 1900. A review of Barnard's notebooks revealed he made many additional brightness estimates up to 1911, and he had also recorded the variations of V1 starting in 1904. These data provide the earliest-epoch light curves for these stars and thus are useful for studying their period changes. This paper presents Barnard's observations of the M13 variables along with their derived heliocentric Julian dates and approximate V magnitudes. These include 231 unpublished observations of V2 and 94 of V1. How these data will be of value for determining period changes by these stars is described.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/1484
- Title:
- Early optical afterglow catalog
- Short Name:
- J/ApJ/693/1484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multicolor optical observations of long-duration {gamma}-ray bursts (GRBs) made over a three-year period with the robotic Palomar 60 inch telescope (P60). Our sample consists of all 29 events discovered by Swift for which P60 began observations less than 1hr after the burst trigger. We were able to recover 80% of the optical afterglows from this prompt sample, and we attribute this high efficiency to our red coverage. Like Melandri et al. (2008, Cat. J/ApJ/686/1209), we find that a significant fraction (~50%) of Swift events show a suppression of the optical flux with regard to the X-ray emission (the so-called "dark" bursts). Our multicolor photometry demonstrates this is likely due in large part to extinction in the host galaxy. We argue that previous studies, by selecting only the brightest and best-sampled optical afterglows, have significantly underestimated the amount of dust present in typical GRB environments.
- ID:
- ivo://CDS.VizieR/J/A+A/459/875
- Title:
- Early spectral evolution of Nova Sgr 2004
- Short Name:
- J/A+A/459/875
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical and near-infrared spectral evolution of the Galactic nova V5114 Sgr (2004) during few months after the outburst. We use multi-band photometry and line intensities derived from spectroscopy to put constrains on the distance and the physical conditions of the ejecta of V5114 Sgr.
- ID:
- ivo://CDS.VizieR/J/ApJ/715/310
- Title:
- Early stages of star formation in IRDCs
- Short Name:
- J/ApJ/715/310
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Identified as extinction features against the bright Galactic mid-infrared background, infrared dark clouds (IRDCs) are thought to harbor the very earliest stages of star and cluster formation. In order to better characterize the properties of their embedded cores, we have obtained new 24um, 60-100um, and submillimeter continuum data toward a sample of 38 IRDCs. The 24um Spitzer images reveal that while the IRDCs remain dark, many of the cores are associated with bright 24um emission sources, which suggests that they contain one or more embedded protostars. Combining the 24um, 60-100um, and submillimeter continuum data, we have constructed broadband spectral energy distributions (SEDs) for 157 of the cores within these IRDCs and, using simple graybody fits to the SEDs, have estimated their dust temperatures, emissivities, opacities, bolometric luminosities, masses, and densities. Based on their Spitzer/Infrared Array Camera 3-8um colors and the presence of 24um point-source emission, we have separated cores that harbor active, high-mass star formation from cores that are quiescent. The active "protostellar" cores typically have warmer dust temperatures and higher bolometric luminosities than the more quiescent, perhaps "pre-protostellar," cores. Because the mass distributions of the populations are similar, however, we speculate that the active and quiescent cores may represent different evolutionary stages of the same underlying population of cores. Although we cannot rule out low-mass star formation in the quiescent cores, the most massive of them are excellent candidates for the "high-mass starless core" phase, the very earliest in the formation of a high-mass star.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/2571
- Title:
- Early-Tyoe Galaxies in SDSS and GALEX
- Short Name:
- J/MNRAS/444/2571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Hernandez-Perez and Bruzual stellar population synthesis models to study the role of interacting binary pairs as progenitors of extreme horizontal branch (EHB) stars. We assemble a sample of 3417 early-type galaxies observed both in the optical (SDSS-DR8) and the UV (GALEX-GR6). The galaxies in our sample can be classified according to their position in the colour-colour diagram as UV-weak or red-sequence galaxies (~48%), UV-strong or UVX galaxies (~9%), and recent star-forming galaxies (~43%). Analysing this sample using the models for various choices of basic model parameters, we conclude that (a) the UVr colours of UV-weak and UV-strong galaxies are reproduced by the models as long as the fraction of binary stars is at least 15%. (b) Higher metallicity models (Z=0.02 and 0.03) reproduce the colours of UV-weak and UV-strong galaxies better than lower Z models. The Z=0.03 model is slightly bluer than the Z=0.02 model in the UV-strong region, indicating a weak relationship between UVX and Z. (c) The strength of UVX increases with age in the model population. This is at variance with the results of other models that include binary stars as progenitors of EHB stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/121
- Title:
- 127 early type and pre-main-sequence stars in W4
- Short Name:
- J/ApJ/899/121
- Date:
- 15 Mar 2022 03:47:36
- Publisher:
- CDS
- Description:
- Stellar kinematics provides the key to understanding the formation process and dynamical evolution of stellar systems. Here, we present a kinematic study of the massive star-forming region (SFR) W4 in the Cassiopeia OB6 association using the Gaia Data Release 2 and high-resolution optical spectra. This SFR is composed of a core cluster (IC1805) and a stellar population distributed over 20pc, which is a typical structural feature found in many OB associations. According to a classical model, this structural feature can be understood in the context of the dynamical evolution of a star cluster. The core-extended structure exhibits internally different kinematic properties. Stars in the core have an almost isotropic motion, and they appear to reach virial equilibrium given their velocity dispersion (0.9{+/-}0.3km/s) comparable to that in a virial state (~0.8km/s). On the other hand, the distributed population shows a clear pattern of radial expansion. From the N-body simulation for the dynamical evolution of a model cluster in subvirial state, we reproduce the observed structure and kinematics of stars. This model cluster experiences collapse for the first 2Myr. Some members begin to radially escape from the cluster after the initial collapse, eventually forming a distributed population. The internal structure and kinematics of the model cluster appear similar to those of W4. Our results support the idea that the stellar population distributed over 20pc in W4 originate from the dynamical evolution of IC1805.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/422
- Title:
- Early-type BCGs with star formation
- Short Name:
- J/MNRAS/423/422
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify a total of 120 early-type brightest cluster galaxies (BCGs) at 0.1<z<0.4 in two recent large cluster catalogues selected from the Sloan Digital Sky Survey (SDSS). They are selected with strong emission lines in their optical spectra, with both H{alpha} and [OII]{lambda}3727 line emission, which indicates significant ongoing star formation. They constitute about ~0.5 per cent of the largest, optically selected, low-redshift BCG sample, and the fraction is a strong function of cluster richness. Their star formation history can be well described by a recent minor and short starburst superimposed on an old stellar component, with the recent episode of star formation contributing on average only less than 1 per cent of the total stellar mass. We show that the more massive star-forming BCGs in richer clusters tend to have higher star formation rate (SFR) and specific SFR (SFR per unit galaxy stellar mass). We also compare their statistical properties with a control sample selected from X-ray luminous clusters, and show that the fraction of star-forming BCGs in X-ray luminous clusters is almost one order of magnitude larger than that in optically selected clusters. BCGs with star formation in cooling flow clusters usually have very flat optical spectra and show the most active star formation, which may be connected with cooling flows.
- ID:
- ivo://CDS.VizieR/J/MNRAS/401/257
- Title:
- Early-type binaries on main sequence
- Short Name:
- J/MNRAS/401/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We showed in a preceding paper based on an analysis of the observed rates of apsidal motion that synchronization in early-type eclipsing binaries continues on the main sequence, and the observed synchronization times, t_syn_, agree with the Zahn's theory (1977A&A....57..383Z) and are inconsistent with the shorter time-scale proposed by Tassoul (1987ApJ...322..856T, 1988ApJ...324L..71T). It follows from this that circularization in early-type binaries must also proceed in accordance with the Zahn's theory because the circularization times, t_circ_, in both theories are rather tightly related to tsyn via relation t_circ_~{alpha}t_syn_, where {alpha} is the orbital-to-axial momentum ratio.
- ID:
- ivo://CDS.VizieR/J/A+A/463/503
- Title:
- Early-type dwarf galaxies in Fornax cluster
- Short Name:
- J/A+A/463/503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the photometric properties of the early-type Fornax cluster dwarf galaxy population, based on a wide field imaging study of the central cluster area in V and I. We used the instrument/telescope combination IMACS/Magellan at Las Campanas Observatory. We create a fiducial sample of Fornax cluster dwarf ellipticals (dEs) in the following three steps: (1) To verify cluster membership, we measured I-band surface brightness fluctuation (SBF) distances to candidate dEs; (2) We re-assessed morphological classifications for candidate dEs too faint for SBF detection; and (3) We searched for new candidate dEs in the size-luminosity regime close to the resolution limit of previous surveys. (1) We confirm cluster membership for 28 candidate dEs in the range -16.6<M_V_<-10.1mag by means of SBF distances. We find no SBF background galaxy. (2) Of 51 further candidate dEs in the range -13.2<M_V_<-8.6mag, 2/3 are confirmed as probable cluster members by morphological re-assessment, while 1/3 are re-classified as probable background objects. (3) We find 12 new dE candidates in the range -12.3<M_V_<-8.8mag. The surface brightness-magnitude relation defined by the resulting fiducial dE sample shows that Fornax dEs are about 40% larger than Local Group dEs. The Fornax dE sample furthermore defines a colour-magnitude relation that appears slightly shallower than that of Local Group dEs. The early-type dwarf galaxy luminosity function in Fornax has a faint end slope alpha=-1.1+/- 0.1.