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- ID:
- ivo://CDS.VizieR/J/ApJ/767/51
- Title:
- Clusters of starburst galaxy NGC4214
- Short Name:
- J/ApJ/767/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The production rate of ionizing photons in young (<=8Myr), unresolved stellar clusters in the nearby irregular galaxy NGC 4214 is probed using multi-wavelength Hubble Space Telescope WFC3 data. We normalize the ionizing photon rate by the cluster mass to investigate the upper end of the stellar initial mass function (IMF). We have found that within the uncertainties the upper end of the stellar IMF appears to be universal in this galaxy, and that deviations from a universal IMF can be attributed to stochastic sampling of stars in clusters with masses {<~}10^3^M_{sun}_. Furthermore, we have found that there does not seem to be a dependence of the maximum stellar mass on the cluster mass. We have also found that for massive clusters, feedback may cause an underrepresentation in H{alpha} luminosities, which needs to be taken into account when conducting this type of analysis.
1323. CMD for And III
- ID:
- ivo://CDS.VizieR/J/AJ/106/986
- Title:
- CMD for And III
- Short Name:
- J/AJ/106/986
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The prime focus CCD camera of the KPNO 4 m telescope has been used to image Andromeda III, a dwarf spheroidal galaxy companion to M31, in the V and I bands. The resulting color-magnitude diagram shows a well defined giant branch whose tip luminosity corresponds to that expected for an old metal-poor population at the distance of M31. By comparing these data with the giant branches of metal-poor population at the distance of M31. By comparing these data with the giant branches of Galactic globular clusters, we determine that the abundance of And III is [Fe/H]=-2.0+/-0.15; with this abundance And III lies on the luminosity-abundance relation defined by the Galactic dwarf spheroidal galaxies. There is some evidence for a small (0.16<{sigma}([Fe/H])<0.24) intrinsic abundance dispersion within And III, but we are unable to unambiguously establish its presence. A study of the And III I-band luminosity function yields a distance modulus (m-M)_0_ of 24.4+/-0.2 for this galaxy, and indicates that the fraction of intermediate-age (3 to 10Gyr) population in And III is approximately 10+/-10 percent. In all these aspects And III, like And I, is similar to the Galactic dwarf spheroidal systems, indicating that M31 and the Galaxy provided similar conditions for the evolution of such galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/125/197
- Title:
- CN abundances of the 47 Tuc main sequence
- Short Name:
- J/AJ/125/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a deep spectroscopic survey for star-to-star CN variations along the main sequence (MS) of the globular cluster 47 Tuc with ESO's Very Large Telescope. We find a significant bimodal distribution in the S(3839) index for main-sequence stars in the mass range ~0.85 to 0.65M_{sun}_, or from the main-sequence turnoff down to ~2.5 mag below the main-sequence turnoff. An anticorrelation of CN and CH is evident on the MS. The result is discussed in the context of the ability of faint MS stars to alter their surface composition through internal evolutionary effects. We argue against internal stellar evolution as the only origin for the abundance spread in 47 Tuc; an external origin such as pollution seems to be more likely.
- ID:
- ivo://CDS.VizieR/J/ApJ/758/110
- Title:
- CN and CH indexes in stars of NGC 6791
- Short Name:
- J/ApJ/758/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low-resolution SDSS/SEGUE spectra have been used to study the behavior of the strengths of the CN and CH molecular bands in stars at different evolutionary stages of the open cluster NGC 6791. We find a significant spread in the strengths of the CN bands, more than twice that expected from the uncertainties, although the bimodalities observed in globular clusters are not clearly observed here. This behavior is observed not only among red clump objects but also in unevolved stars such as those in the main sequence and lower red giant branch. In contrast, not all of the stars studied show significant scatter in their CH strengths.
- ID:
- ivo://CDS.VizieR/J/AJ/142/126
- Title:
- CN and CH in SDSS Galactic globular clusters
- Short Name:
- J/AJ/142/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a homogeneous survey of the CN and CH band strengths in eight Galactic globular clusters observed during the course of the Sloan Extension for Galactic Understanding and Exploration sub-survey (SEGUE) of the Sloan Digital Sky Survey. We confirm the existence of a bimodal CN distribution among red giant branch (RGB) stars in all of the clusters with metallicity greater than [Fe/H]=-1.7; the lowest metallicity cluster with an observed CN bimodality is M53, with [Fe/H]~=-2.1. There is also some evidence for individual CN groups on the subgiant branches of M92, M2, and M13, and on the RGBs of M92 and NGC 5053. Finally, we quantify the correlation between overall cluster metallicity and the slope of the CN band strength-luminosity plot as a means of further demonstrating the level of CN enrichment in cluster giants. Our results agree well with previous studies reported in the literature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/408/181
- Title:
- CN2002ch UBVRI and ugriz light curves
- Short Name:
- J/MNRAS/408/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometric and spectroscopic observations of an unusual luminous blue variable (LBV) in NGC 3432, covering three major outbursts in 2008 October, 2009 April and 2009 November. Previously, this star experienced an outburst also in 2000 (known as SN 2000ch). During outbursts the star reached an absolute magnitude between -12.1 and -12.8. Its spectrum showed H, HeI and FeII lines with P-Cygni profiles during and soon after the eruptive phases, while only intermediate-width lines in pure emission (including HeII {lambda}4686) were visible during quiescence. The fast-evolving light curve soon after the outbursts, the quasi-modulated light curve, the peak magnitude and the overall spectral properties are consistent with multiple episodes of variability of an extremely active LBV. However, the widths of the spectral lines indicate unusually high wind velocities (1500-2800km/s), similar to those observed in Wolf-Rayet stars. Although modulated light curves are typical of LBVs during the S-Dor variability phase, the luminous maxima and the high frequency of outbursts are unexpected in S-Dor variables.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A1
- Title:
- 55 Cnc radial velocities and photometry
- Short Name:
- J/A+A/619/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbiting a bright, nearby star the 55 Cnc system offers a rare opportunity to study a multiplanet system that has a wide range of planetary masses and orbital distances. Using two decades of photometry and spectroscopy data, we have measured the rotation of the host star and its solar-like magnetic cycle. Accounting for this cycle in our velocimetric analysis of the system allows us to revise the properties of the outermost giant planet and its four planetary companions. The innermost planet 55 Cnc e is an unusually close-in super-Earth, whose transits have allowed for detailed follow-up studies. Recent observations favor the presence of a substantial atmosphere yet its composition, and the nature of the planet, remain unknown. We combined our derived planet mass (Mp=8.0+/-0.3M_{Earth}_) with refined measurement of its optical radius derived from HST/STIS observations (Rp=1.88+/-0.03R_{Earth}_ over 530-750nm) to revise the density of 55 Cnc e (rho=6.7+/-0.4g/cm^3^). Based on these revised properties we have characterized possible interiors of 55 Cnc e using a generalized Bayesian model. We confirm that the planet is likely surrounded by a heavyweight atmosphere, contributing a few percents of the planet radius. While we cannot exclude the presence of a water layer underneath the atmosphere, this scenario is unlikely given the observations of the planet across the entire spectrum and its strong irradiation. Follow-up observations of the system in photometry and in spectroscopy over different time-scales are needed to further investigate the nature and origin of this iconic super-Earth.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A28
- Title:
- 3C 294 NIR images and optical spectra
- Short Name:
- J/A+A/628/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High redshift radio galaxies are among the most massive galaxies at their redshift, are often found in the centers of proto-clusters of galaxies, and are expected to evolve into the present day massive central cluster galaxies. Thus they are a useful tool to explore structure formation in the young Universe. 3C 294 is a powerful FR II type radio galaxy at z=1.786. Past studies have identified a clumpy structure, possibly indicative of a merging system, as well as tentative evidence that 3C 294 hosts a dual AGN. Due to its proximity to a bright star, it was subject to various adaptive optics imaging studies. In order to distinguish between the various scenarios for 3C 294 we performed deep high-resolution adaptive optics imaging and optical spectroscopy of 3C 294 with the Large Binocular Telescope. We resolve the 3C 294 system into three distinct components separated by a few tenths of an arcsecond on our images. One is compact, the other two are extended, all appear to be non-stellar. The nature of each component is unclear. The latter could be a galaxy with an internal absorption feature, a galaxy merger or two galaxies at different redshifts. We can now uniquely associate the radio source of 3C 294 with one of the extended components. Based on our spectroscopy, we determined a redshift of z=1.784+/-0.001, which is similar to the one previously cited. In addition we found a previously unreported emission line at lambda 6749.4{AA} in our spectra. It is not clear that it originates from 3C 294. It could be the Ne [IV] doublet lambda 2424/2426{AA} at z=1.783, or belong to the compact component at a redshift of z~4.56. We thus can not unambiguously determine whether 3C 294 hosts a dual AGN or a projected pair of AGNs.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2347
- Title:
- CO And Vr light curves and RV curve
- Short Name:
- J/AJ/139/2347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate absolute properties have been determined for the eclipsing triple star CO And (F8+F8) based on extensive differential photometry obtained by three robotic observatories and CfA spectroscopy. The eclipsing binary star orbit is circular with a period of 3.655days. The triple nature of this system is revealed by more than a century of timings of minimum light, and by the presence of third light in the photometric orbits.
