Search

Start Over Subject photometry
1331. CN abundances of the 47 Tuc main sequence
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.
1332. CN and CH indexes in stars of NGC 6791
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.
1333. CN and CH in SDSS Galactic globular clusters
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.
1334. CN2002ch UBVRI and ugriz light curves
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.
1335. 55 Cnc radial velocities and photometry
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.
1336. 3C 294 NIR images and optical spectra
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.
1337. CO And Vr light curves and RV curve
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.
1338. Cobalt emission in nebular phase spectra
ID:
ivo://CDS.VizieR/J/MNRAS/454/3816
Title:
Cobalt emission in nebular phase spectra
Short Name:
J/MNRAS/454/3816
Date:
21 Oct 2021
Publisher:
CDS
Description:
The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of ^56^Ni to ^56^Co at early times, and the decay of ^56^Co to ^56^Fe from ~60 d after explosion. We examine the evolution of the [CoIII] {lambda}5893 emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of ^56^Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in ^56^Co decay and long-term stability of the ionization state of the nebula. We compile SN Ia nebular spectra from the literature and present 21 new late-phase spectra of 7 SNe Ia, including SN 2014J. From these we measure the flux in the [CoIII] {lambda}5893 line and remove its well-behaved time dependence to infer the initial mass of ^56^Ni (M_Ni_) produced in the explosion. We then examine ^56^Ni yields for different SN Ia ejected masses (M_ej_ - calculated using the relation between light-curve width and ejected mass) and find that the ^56^Ni masses of SNe Ia fall into two regimes: for narrow light curves (low stretch s~0.7-0.9), M_Ni_ is clustered near M_Ni_~0.4M_{sun}_ and shows a shallow increase as M_ej_ increases from ~1 to 1.4M_{sun}_; at high stretch, M_ej_ clusters at the Chandrasekhar mass (1.4M_{sun}_) while M_Ni_ spans a broad range from 0.6 to 1.2M_{sun}_. This could constitute evidence for two distinct SN Ia explosion mechanisms.
1339. COBE DIRBE IR photometry
ID:
ivo://CDS.VizieR/J/ApJ/500/554
Title:
COBE DIRBE IR photometry
Short Name:
J/ApJ/500/554
Date:
21 Oct 2021
Publisher:
CDS
Description:
A comparison of the COBE Diffuse Infrared Background Experiment (DIRBE) all-sky survey with the locations of known galaxies in the IRAS Catalog of Extragalactic Objects and the Center for Astrophysics Catalog of Galaxies led to the detection of as many as 57 galaxies. In this paper, we present the photometric data for these galaxies and an analysis of the seven galaxies that were detected at {lambda}>100{mu}m. Estimates of the ratio of the mass of the cold dust (CD) component detected at T_d_=20-30K to a very cold dust (VCD) component with T_d_~10-15K suggest that between 2%-100% of the cirrus-like CD mass can also exist in many of these galaxies as VCD. In one galaxy, M33, the DIRBE photometry at 240{mu}m suggests as much as 26 times as much VCD may be present as compared to the cirrus-like component. Further submillimeter measurements of this galaxy are required to verify such a large population of VCD. We also present 10 galaxies that were detected in the sky region not previously surveyed by IRAS and that can be used to construct a flux-limited all-sky catalog of galaxies brighter than 1000Jy with a modest completeness limit of about 65%.
1340. COBE DIRBE Point Source Catalog
ID:
ivo://CDS.VizieR/J/ApJS/154/673
Title:
COBE DIRBE Point Source Catalog
Short Name:
J/ApJS/154/673
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the COBE DIRBE Point Source Catalog, an all-sky catalog containing infrared photometry in 10 bands from 1.25 microns to 240 microns for 11788 of the brightest near and mid-infrared point sources in the sky. Since DIRBE had excellent temporal coverage (100-1900 independent measurements per object during the 10 month cryogenic mission), the Catalog also contains information about variability at each wavelength, including amplitudes of variation observed during the mission. Since the DIRBE spatial resolution is relatively poor (0.7{deg}), we have carefully investigated the question of confusion, and have flagged sources with infrared-bright companions within the DIRBE beam. In addition, we filtered the DIRBE light curves for data points affected by companions outside of the main DIRBE beam but within the `sky' portion of the scan. At high Galactic latitudes (|b|>5{deg}), the Catalog contains essentially all of the unconfused sources with flux densities greater than 90, 60, 60, 50, 90, and 165 Jy at 1.25, 2.2, 3.5, 4.9, 12, and 25 microns, respectively, corresponding to magnitude limits of approximately 3.1, 2.6, 1.7, 1.3, -1.3, and -3.5. At longer wavelengths and in the Galactic Plane, the completeness is less certain because of the large DIRBE beam and possible contributions from extended emission. The Catalog also contains the names of the sources in other catalogs, their spectral types, variability types, and whether or not the sources are known OH/IR stars. We discuss a few remarkable objects in the Catalog.