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5181. Photometry of V700 Cyg and AW Vir
ID:
ivo://CDS.VizieR/J/A+AS/124/291
Title:
Photometry of V700 Cyg and AW Vir
Short Name:
J/A+AS/124/291
Date:
21 Oct 2021
Publisher:
CDS
Description:
A photometric analysis of the W UMa systems V 700 Cyg and AW Vir, based on photoelectric B and V light curves, is presented. Since no spectroscopic mass-ratio is available, the q-search method was applied to find the preliminary range of the mass-ratio in order to search for the final solution. First, an unspotted solution was carried out by using the unperturbed parts of the light curves and applying the DC program of the WD code. The final spotted solution was made by adopting spot models for the two systems. In the case of V 700 Cyg, two cool spots were placed on the primary (more massive, larger and cooler) component to explain the O'Connell effect (MaxII fainter than MaxI) and a small deficit of light just before MaxI. In the case of AW Vir, one cool spot was placed on the primary component to explain the relatively large O'Connell effect. Both objects are W-type systems with partial eclipses; V 700 Cyg is fairly evolved while AW Vir is rather unevolved.
5182. Photometry of VdBH 222 stars and field stars
ID:
ivo://CDS.VizieR/J/A+A/567/A73
Title:
Photometry of VdBH 222 stars and field stars
Short Name:
J/A+A/567/A73
Date:
21 Oct 2021
Publisher:
CDS
Description:
It has been suggested that the compact open cluster VdBH 222 is a young massive distant object. We set out to characterise VdBH 222 using a comprehensive set of multi-wavelength observations. We obtained multi-band optical (UBVR) and near-infrared (JHKs) photometry of the cluster field, as well as multi-object and long-slit optical spectroscopy for a large sample of stars in the field. We applied classical photometric analysis, as well as more sophisticated methods using the CHORIZOS code, to determine the reddening to the cluster. We then plotted dereddened HR diagrams and determined cluster parameters via isochrone fitting.
5183. Photometry of VVV CL041 cluster
ID:
ivo://CDS.VizieR/J/A+A/584/A31
Title:
Photometry of VVV CL041 cluster
Short Name:
J/A+A/584/A31
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ESO Public Survey VISTA Variables in the Via Lactea (VVV) provides deep multi-epoch infrared observations for an unprecedented 562 sq. deg of the Galactic bulge and adjacent regions of the disk. Nearly 150 new open clusters and cluster candidates have been discovered in this survey. We present the fourth article in a series of papers focussed on young and massive clusters discovered in the VVV survey. This article is dedicated to the cluster VVV CL041, which contains a new very massive star candidate, WR 62-2. Following the methodology presented in the first paper of the series, wide-field, deep JHKs VVV observations, combined with new infrared spectroscopy, are employed to constrain fundamental parameters (distance, reddening, mass, age) of VVV CL041.
5184. Photometry of WN8 Stars
ID:
ivo://CDS.VizieR/J/AJ/109/817
Title:
Photometry of WN8 Stars
Short Name:
J/AJ/109/817
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results of an extensive photometric study of the most intrinsically variable Wolf-Rayet stars: the WN8 subclass. Some 375 individual differential observations of WR16 and WR40 were obtained over a contiguous interval of ~3 months in a narrow visual continuum bandpass. Over the same interval, we obtained roughly 200 broadband V observations of the fainter WN8 stars WR66 and WR82. All four WN8 stars show significant random variability on time scales of hours to ~a day -- probably related to the stochastic formation, propagation, and decay of emitting/scattering inhomogeneities in the winds. Unlike for WR66 and WR82, the photometric behaviour of WR16 and WR40 is more deterministic with ~two possible periods in the range ~2-30 days -- possibly related to some kind of LBV, binary, or rotation phenomenon. In addition, WR82 shows a possible secular decline during the 3 months and WR66 reveals a clear periodicity of 3.51 h. This short period may be related to nonradial pulsations or a spiral-in binary process invoking a low-mass, compact companion as seen in the massive x-ray binary Cyg X-3, a WN7 + c system of period 4.8 h.
5185. Photometry of W UMa eclipsing binaries
ID:
ivo://CDS.VizieR/J/AJ/143/99
Title:
Photometry of W UMa eclipsing binaries
Short Name:
J/AJ/143/99
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on a BVRcIc survey of field W Ursae Majoris (UMa) binary stars and present accurate colors for 606 systems that have been observed on at least three photometric nights from a robotic observatory in southern Arizona. Comparison with earlier photometry for a subset of the systems shows good agreement. We investigate two independent methods of determining the interstellar reddening, although both have limitations that can render them less effective than desired. A subset of 101 systems shows good agreement between the two reddening methods.
5186. Photometry of young star groupings in spirals
ID:
ivo://CDS.VizieR/J/A+A/357/437
Title:
Photometry of young star groupings in spirals
Short Name:
J/A+A/357/437
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present multiband photometric observations of three spiral galaxies selected in a sample suited for the study of young stellar groupings and their relationship with the parent galaxy and the galactic environment. Star forming regions have been identified using an objective technique based on a multivariate statistical analysis. Maps of young star groupings are given for each galaxy. The luminosity functions of the young star group populations show a remarkable similarity with a slope in the range -1.52 to -1.33. The size distributions peak around the classical 100pc value of the Local Group associations for two out of the three galaxies. NGC 1058 shows smaller associations (peak at ~50pc). The total number of young groups per unit B absolute luminosity of the galaxy is significantly greater in UGC 12732. The activity of star formation is in all three galaxies clearly stronger in the central regions.
5187. Photometry of YSOs in BRC 27 and BRC 34
ID:
ivo://CDS.VizieR/J/AJ/145/15
Title:
Photometry of YSOs in BRC 27 and BRC 34
Short Name:
J/AJ/145/15
Date:
21 Oct 2021
Publisher:
CDS
Description:
We used archival Spitzer Space Telescope mid-infrared data to search for young stellar objects (YSOs) in the immediate vicinity of two bright-rimmed clouds, BRC 27 (part of CMa R1) and BRC 34 (part of the IC 1396 complex). These regions both appear to be actively forming young stars, perhaps triggered by the proximate OB stars. In BRC 27, we find clear infrared excesses around 22 of the 26 YSOs or YSO candidates identified in the literature, and identify 16 new YSO candidates that appear to have IR excesses. In BRC 34, the one literature-identified YSO has an IR excess, and we suggest 13 new YSO candidates in this region, including a new Class I object. Considering the entire ensemble, both BRCs are likely of comparable ages, within the uncertainties of small number statistics and without spectroscopy to confirm or refute the YSO candidates. Similarly, no clear conclusions can yet be drawn about any possible age gradients that may be present across the BRCs.
5188. Photometry of YSOs in eight bright-rimmed clouds
ID:
ivo://CDS.VizieR/J/AJ/151/126
Title:
Photometry of YSOs in eight bright-rimmed clouds
Short Name:
J/AJ/151/126
Date:
21 Oct 2021
Publisher:
CDS
Description:
We carried out deep- and wide-field near- and mid-infrared observations for a sample of eight bright-rimmed clouds (BRCs). Supplemented with the Spitzer archival data, we have identified and classified 44 to 433 young stellar objects (YSOs) associated with these BRCs. The Class I sources are generally located toward the places with higher extinction and are relatively closer to each other than the Class II sources, confirming that the young protostars are usually found in regions with denser molecular material. On the other hand the comparatively older population, Class II objects, are more randomly found throughout the regions, which can be due to their dynamical evolution. Using the minimal sampling tree analyses, we have extracted 13 stellar cores of eight or more members, which contain 60% of the total YSOs. The typical core is ~0.6pc in radii and somewhat elongated (aspect ratio of 1.45), of relatively low stellar density (surface density 60pc^-2^), consisting of a small (35) number of YSOs of relatively young sources (66% Class I), and partially embedded (median A_K_=1.1mag). But the cores show a wide range in their mass distribution (~20 to 2400M_{Sun}_), with a median value of around 130M_{Sun}_. We found the star-formation efficiencies in the cores to be between 3% and 30% with an average of ~14%, which agrees with the efficiencies needed to link the core mass function to the initial mass function. We also found a linear relation between the density of the clouds and the number of YSOs. The peaked nearest neighbor spacing distributions of the YSOs and the ratio of Jeans lengths to the YSO separations indicates a significant degree of non-thermally driven fragmentation in these BRCs.
5189. Photometry of Zwicky Galaxies
ID:
ivo://CDS.VizieR/J/AJ/110/1083
Title:
Photometry of Zwicky Galaxies
Short Name:
J/AJ/110/1083
Date:
21 Oct 2021
Publisher:
CDS
Description:
Multiaperture photoelectric measurements in the B and V bands are presented for 601 galaxies in Volumes I, II, and V of Zwicky's catalogue. Large aperture observations were made in the 1960's with the Lick 3 m telescope and the USNO 1 m telescope. Systematics in Zwicky's magnitude system are investigated as a function of magnitude and direction in the sky. The photoelectric sample is argued to be representative of galaxies in Zwicky's catalogue at B ~ 15. A strong systematic error in Zwicky's magnitudes is apparent in Volume I fainter than m_z = 15.0. The B-V color distribution is discussed.
5190. Photometry & RV follow-up observations of K2-18
ID:
ivo://CDS.VizieR/J/AJ/155/257
Title:
Photometry & RV follow-up observations of K2-18
Short Name:
J/AJ/155/257
Date:
21 Oct 2021
Publisher:
CDS
Description:
K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet that was first discovered by the K2 mission and later confirmed with Spitzer Space Telescope observations. With a radius of ~2 R_{Earth}_ and an orbital period of ~33 days, the planet lies in the temperate zone of its host star and receives stellar irradiation similar to that of Earth. Here we perform radial velocity follow-up observations with the visual channel of CARMENES with the goal of determining the mass and density of the planet. We measure a planetary semi-amplitude of K_b_~3.5 m/s and a mass of M_b_~9 M_{Earth}_, yielding a bulk density around {rho}_b_~4 g/cm^3^. This indicates a low-mass planet with a composition consistent with a solid core and a volatile-rich envelope. A signal at 9 days was recently reported using radial velocity measurements taken with the HARPS spectrograph. This was interpreted as being due to a second planet. We see a weaker, time- and wavelength-dependent signal in the CARMENES data set and thus favor stellar activity for its origin. K2-18 b joins the growing group of low-mass planets detected in the temperate zone of M dwarfs. The brightness of the host star in the near-infrared makes the system a good target for detailed atmospheric studies with the James Webb Space Telescope.