- ID:
- ivo://CDS.VizieR/J/ApJ/824/5
- Title:
- Chemical abundances in NGC 5024 (M53)
- Short Name:
- J/ApJ/824/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Fe, Ca, Ti, Ni, Ba, Na, and O abundances for a sample of 53 red giant branch stars in the globular cluster (GC) NGC 5024 (M53). The abundances were measured from high signal-to-noise medium resolution spectra collected with the Hydra multi-object spectrograph on the Wisconsin-Indiana-Yale-NOAO 3.5m telescope. M53 is of interest because previous studies based on the morphology of the cluster's horizontal branch suggested that it might be composed primarily of first generation (FG) stars and differ from the majority of other GCs with multiple populations, which have been found to be dominated by the second generation (SG) stars. Our sample has an average [Fe/H]=-2.07 with a standard deviation of 0.07dex. This value is consistent with previously published results. The alpha-element abundances in our sample are also consistent with the trends seen in Milky Way halo stars at similar metallicities, with enhanced [Ca/Fe] and [Ti/Fe] relative to solar. We find that the Na-O anti-correlation in M53 is not as extended as other GCs with similar masses and metallicities. The ratio of SG to the total number of stars in our sample is approximately 0.27 and the SG generation is more centrally concentrated. These findings further support that M53 might be a mostly FG cluster and could give further insight into how GCs formed the light element abundance patterns we observe in them today.
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- ID:
- ivo://CDS.VizieR/J/A+A/459/871
- Title:
- Chemically peculiar stars in the LMC
- Short Name:
- J/A+A/459/871
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high precision photometric Delta a observations of 417 objects in NGC 2136/7 and its surrounding field, of which five turned out to be bona fide magnetic CP stars. In addition, we discovered two Be/Ae stars. This intermediate band photometric system samples the depth of the 520nm flux depression by comparing the flux at the center with the adjacent regions with bandwidths of 11nm to 23nm. The Delta a photometric system is most suitable for detecting CP2 stars with high efficiency, but is also capable of detecting a small percentage of non-magnetic CP objects. From our investigations of NGC 1711, NGC 1866, NGC 2136/7, their surroundings, and one independent field of the LMC population, we derive an occurrence of classical chemically peculiar stars of 2.2(6)% in the LMC, which is only half the value found in the Milky Way. The mass and age distribution of the photometrically detected CP stars is not different from that of similar objects in galactic open clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/2139
- Title:
- CI Cyg BVRcIc light curves
- Short Name:
- J/MNRAS/399/2139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we discuss the early phases of the ongoing outburst that CI Cyg, a prototype symbiotic star, is currently undergoing after 30-year quiescence. We have tightly monitored CI Cyg in B V R_C_ I_C_ bands, starting a whole year before the onset of the outburst, and in addition we obtained numerous Echelle high- and low-resolution absolutely flux-calibrated spectra. The outburst started while the accreting white dwarf (WD) was being eclipsed by the Roche lobe filling M giant companion, and it was discovered during the egress phase on the second half of 2008 August. The system reached peak V-band brightness in early 2008 October and has been characterized by amplitudes {delta}B=1.9, {delta}V=1.5, {delta}R_C_=0.9, {delta}I_C_=0.4mag. At maximum V-band brightness, the outbursting WD had expanded to closely resemble an F3 II/Ib star, with MV=-3.5, Teff~6900K and R=28R_{sun}_. The high-ionization emission lines ([NeV], [FeVII], HeII) disappeared and only lower ionization lines were visible. Balmer and He I emission lines declined in equivalent width but increased in absolute flux. The output radiated by the hot component during the outburst corresponds to nuclear burning proceeding at a 2x10^-8^M_{sun}_/yr rate.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/3173
- Title:
- Circumnuclear star-forming regions
- Short Name:
- J/MNRAS/451/3173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry in U, B, V, R and I continuum bands and in H{alpha} and H{beta} emission lines for a sample of 336 circumnuclear star-forming regions located in early-type spiral galaxies with different levels of activity in their nuclei. They are nearby galaxies, with distances less than 100Mpc, 60 per cent of which are considered as interacting objects. This survey of 20 nuclear rings aims to provide insight into their star formation properties as age, stellar population and star formation rate. Extinction-corrected H{alpha} luminosities range from 1.3x10^38^ to 4x10^41^erg/s, with most of the regions showing values between 39.5<=logL_H{alpha}_<=40, which implies masses for the ionizing clusters higher than 2x10^5^M_{sun}_. H{alpha} and H{beta} images have allowed us to obtain an accurate measure of extinction. We have found an average value of A_V_=1.85 mag. (U-B) colour follows a two maximum distribution around (U-B)=~-0.7, and -0.3; (R-I) also presents a bimodal behaviour, with maximum values of 0.6 and 0.9. Reddest (U-B) and (R-I) regions appear in non-interacting galaxies. Reddest (R-I) regions lie in strongly barred galaxies. For a significant number of HII regions, the observed colours and equivalent widths are not well reproduced by single burst evolutionary theoretical models.
- ID:
- ivo://CDS.VizieR/J/AJ/119/3026
- Title:
- Circumstellar disk candidates in Orion
- Short Name:
- J/AJ/119/3026
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical study of four 45'x45' fields centered ~0.5{deg} east, west, north, and south of the Orion Nebula Cluster center. We have measured V and I_C_ photometry for ~5000 stars, and U photometry for ~1600 of these. We have obtained spectral classifications for ~300 of the stars with UVI_C_ photometry plus an additional ~200 stars located outside the area of our photometric survey. Dereddened photometry allows us to investigate the evidence for circumstellar accretion disks from excess emission at ultraviolet wavelengths, as well as the mass and age distributions of our sample. We find ~230 active accretion disk candidates and estimate the accretion disk fraction at >~40%. We use the magnitude of the ultraviolet excess to infer disk accretion rates. The mass accretion rate (dM/dt) decreases slowly with age over the limited age range spanned by our data, 1-3Myr, and increases slowly with mass over the limited mass range 0.2-1.2 M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A131
- Title:
- Circumstellar-interacting supernovae
- Short Name:
- J/A+A/580/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Some circumstellar-interacting (CSI) supernovae (SNe) are produced by the explosions of massive stars that have lost mass shortly before the SN explosion. There is evidence that the precursors of some SNe IIn were luminous blue variable (LBV) stars. For a small number of CSI SNe, outbursts have been observed before the SN explosion. Eruptive events of massive stars are named SN impostors (SN IMs) and whether they herald a forthcoming SN or not is still unclear. The large variety of observational properties of CSI SNe suggests the existence of other progenitors, such as red supergiant (RSG) stars with superwinds. Furthermore, the role of metallicity in the mass loss of CSI SN progenitors is still largely unexplored. Our goal is to gain insight into the nature of the progenitor stars of CSI SNe by studying their environments, in particular the metallicity at their locations. We obtain metallicity measurements at the location of 60 transients (including SNe IIn, SNe Ibn, and SN IMs) via emission-line diagnostic on optical spectra obtained at the Nordic Optical Telescope and through public archives. Metallicity values from the literature complement our sample. We compare the metallicity distributions among the different CSI SN subtypes, and to those of other core-collapse SN types. We also search for possible correlations between metallicity and CSI SN observational properties. We find that SN IMs tend to occur in environments with lower metallicity than those of SNe IIn. Among SNe IIn, SN IIn-L(1998S-like) SNe show higher metallicities, similar to those of SNe IIL/P, whereas long-lasting SNe IIn (1988Z-like) show lower metallicities, similar to those of SN IMs. The metallicity distribution of SNe IIn can be reproduced by combining the metallicity distributions of SN IMs (which may be produced by major outbursts of massive stars like LBVs) and SNe IIP (produced by RSGs). The same applies to the distributions of the normalized cumulative rank (NCR) values, which quantifies the SN association to HII regions. For SNe IIn, we find larger mass-loss rates and higher CSM velocities at higher metallicities. The luminosity increment in the optical bands during SN IM outbursts tend to be larger at higher metallicity, whereas the SN IM quiescent optical luminosities tend to be lower. The difference in metallicity between SNe IIn and SN IMs indicates that LBVs are only one of the progenitor channels for SNe IIn, with 1988Z-like and 1998S-like SNe possibly arising from LBVs and RSGs, respectively. Finally, even though line-driven winds likely do not primarily drive the late mass-loss of CSI SN progenitors, metallicity has some impact on the observational properties of these transients.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2669
- Title:
- CL Aur BVRI light curves
- Short Name:
- J/AJ/139/2669
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first extensive photometric results of CL Aur from our BVRI CCD photometry made on 22 nights from 2003 November to 2005 February. Fifteen new timings of minimum light were obtained. During the past 104yr, the orbital period has varied due to a periodic oscillation superposed on a continuous period increase. The period and semi-amplitude of the oscillation are about 21.6yr and 0.0133-day, respectively.
- ID:
- ivo://CDS.VizieR/J/other/Obs/131.315
- Title:
- CL Eri, CM Eri, CN Eri BVIc light curves
- Short Name:
- J/other/Obs/131.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of total of 1071 B, V, Ic-band CCD frames are taken for three GCVS RR Lyr-type variables (CL Eri, CM Eri, and CN Eri), for which only coordinates were known. Observations were made with the 76-cm telescope of the South African Astronomical Observatory using an SBIG CCD ST-10XME. The inferred periods and light-curves confirm that CL Eri (P=0.644d), which was found to exhibit the Blazhko effect, and CN Eri (P=0.580d) are RR Lyr-type variables. CM Eri is most probably a Population-Il Cepheid with a period of 0.824d.
- ID:
- ivo://CDS.VizieR/J/AJ/116/584
- Title:
- Cl J0023+0423 and Cl J1604+4304 morphology
- Short Name:
- J/AJ/116/584
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed morphological analysis of the galaxy populations in the first two clusters to be completed in an extensive observational study of nine high-redshift clusters of galaxies. These two clusters, Cl 0023+0423 and Cl 1604+4304, are at redshifts of z=0.84 and z=0.90, respectively. The morphological studies are based on high angular resolution imagery taken with Wide Field Planetary Camera 2 aboard the Hubble Space Telescope. These data are combined with deep, ground-based BVRI photometry and spectra taken with the Keck 10m telescopes. The morphological classifications presented in this paper consist of two parts. First, we provide a quantitative description of the structural properties of ~600 galaxies per cluster field using the Medium Deep Survey automated data reduction and object classification software. This analysis includes the galaxy position, photometry, and best-fit bulge+disk model. Second, for the brightest subsample of ~200 galaxies per cluster field, we provide a more detailed morphological description through a visual classification based on the revised Hubble classification scheme.
- ID:
- ivo://CDS.VizieR/J/AJ/116/560
- Title:
- Cl J0023+0423 and Cl J1604+4304 spectroscopy
- Short Name:
- J/AJ/116/560
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extensive photometric and spectroscopic study of two high-redshift clusters of galaxies based on data obtained from the Keck 10m telescopes and the Hubble Space Telescope. The clusters Cl 0023+0423 (z=0.84) and Cl 1604+4304 (z=0.90) are part of a multiwavelength program of Oke, Postman & Lubin (1998AJ....116..549O, Paper I) to study nine candidate clusters at z>~0.6. Based on these observations, we study in detail both the field and cluster populations. From the confirmed cluster members, we find that Cl 0023+0423 actually consists of two components separated by ~2900km/s. A kinematic analysis indicates that the two components are a poor cluster with ~3x10^14^M_{sun}_ and a less massive group with ~10^13^M_{sun}_. Cl 1604+4304 is a centrally concentrated, rich cluster at z=0.8967 with a velocity dispersion of 1226km/s and a mass of ~3x10^15^M_{sun}_.
