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4281. New low-mass eclipsing binary from SDSS-II
ID:
ivo://CDS.VizieR/J/ApJ/684/635
Title:
New low-mass eclipsing binary from SDSS-II
Short Name:
J/ApJ/684/635
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present observations of a new low-mass, double-lined eclipsing binary system discovered using repeat observations of the celestial equator from the Sloan Digital Sky Survey II. Using near-infrared photometry and optical spectroscopy we have measured the properties of this short-period [P=0.407037(14)days] system and its two components. We find the following parameters for the two components: M_1_=0.272+/-0.020M_{sun}_, R_1_=0.268+/-0.010R_{sun}_, M_2_=0.240+/-0.022M_{sun}_, R_2_=0.248+/-0.0090R_{sun}_, T_1_=3320+/-130K, and T_2_=3300+/-130K. The masses and radii of the two components of this system agree well with theoretical expectations based on models of low-mass stars, within the admittedly large errors.
4282. Newly identified star clusters in M 31
ID:
ivo://CDS.VizieR/J/PASP/125/636
Title:
Newly identified star clusters in M 31
Short Name:
J/PASP/125/636
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the HST archives, we have searched portions of the southern half and northwest quarter of the Andromeda Galaxy (M 31, NGC 224) for previously unrecognized star clusters. The result is a table of the characteristics of 71 newly identified star clusters. Most are moderately faint, low-mass clusters. Absolute magnitudes range from M(V)=-6.3 to -2.5.
4283. Newly identified star clusters in M33. II.
ID:
ivo://CDS.VizieR/J/ApJ/699/839
Title:
Newly identified star clusters in M33. II.
Short Name:
J/ApJ/699/839
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present integrated photometry and color-magnitude diagrams (CMDs) for 161 star clusters in M33, of which 115 were previously uncataloged, using the Advanced Camera For Surveys Wide Field Channel onboard the Hubble Space Telescope. The integrated V-band magnitudes of these clusters range from M_V_~-9 to as faint as M_V_~-4, extending the depth of the existing M33 cluster catalogs by ~1mag. Comparisons of theoretical isochrones to the CMDs using the Padova models yield ages for 148 of these star clusters. The ages range from log(t)~7.0 to log(t)~9.0. Our CMDs are not sensitive to clusters older than ~1Gyr. We find that the variation of the clusters' integrated colors and absolute magnitudes with age is consistent with the predictions of simple stellar population models. These same models suggest that the masses of the clusters in our sample range from 5x10^3^ to 5x10^4^M_{sun}_.
4284. Newly rich galaxy clusters identified in SDSS-DR12
ID:
ivo://CDS.VizieR/J/ApJ/807/178
Title:
Newly rich galaxy clusters identified in SDSS-DR12
Short Name:
J/ApJ/807/178
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurately determining the mass of galaxy clusters is fundamental for many studies of cosmology and galaxy evolution. We collect and rescale the cluster masses of 1191 clusters of 0.05<z<0.75 estimated by X-ray or Sunyaev-Zeldovich measurements and use them to calibrate the optical mass proxy. The total r-band luminosity (in units of L*) of these clusters is obtained by using spectroscopic and photometric data of the Sloan Digital Sky Survey (SDSS). We find that the correlation between the cluster mass M_500_ and total r-band luminosity L_500_ significantly evolves with redshift. After correcting for the evolution, we define a new cluster richness R_L*,500_=L_500_E(z)^1.40^ as the optical mass proxy. By using this newly defined richness and the recently released SDSS DR12 spectroscopic data, we update the WHL12 (Wen et al. 2012, J/ApJS/199/34) cluster catalog and identify 25419 new rich clusters at high redshift. In the SDSS spectroscopic survey region, about 89% of galaxy clusters have spectroscopic redshifts. The mass can be estimated with a scatter of 0.17dex for the clusters in the updated catalog.
4285. Newly spectroscopically confirmed DB white dwarfs
ID:
ivo://CDS.VizieR/J/PASP/130/H4203
Title:
Newly spectroscopically confirmed DB white dwarfs
Short Name:
J/PASP/130/H4203
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using a machine learning (ML) method, we mine DB white dwarfs (DBWDs) from the Sloan Digital Sky Survey (SDSS) Data Release (DR) 12 and DR14. The ML method consists of two parts: feature extraction and classification. The least absolute shrinkage and selection operator (LASSO) is used for the spectral feature extraction by comparing high quality data of a positive sample group with negative sample groups. In both the training and testing sets, the positive sample group is composed of a selection of 300 known DBWDs, while the negative sample groups are obtained from all types of SDSS spectra. In the space of the LASSO detected features, a support vector machine is then employed to build classifiers that are used to separate the DBWDs from the non-DBWDs for each individual type. Depending on the classifiers, the DBWD candidates are selected from the entire SDSS data set. After visual inspection, 2808 spectra (2029 objects) are spectroscopically confirmed. By checking the samples with the literature, there are 58 objects with 60 spectra that are newly identified, including a newly discovered AM CVn. Finally, we measure their effective temperatures (T_eff_), surface gravities (log g), and radial velocities, before compiling them into a catalog.
4286. New M dwarfs in solar neighborhood
ID:
ivo://CDS.VizieR/J/AJ/132/866
Title:
New M dwarfs in solar neighborhood
Short Name:
J/AJ/132/866
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results from a spectroscopic study of 1063 nearby active M dwarfs, selected by correlating the Two Micron All Sky Survey and ROSAT catalogs. We have derived the spectral types and estimated distances for all of our stars. The spectral types range between K5 and M6. Nearly half of our stars lie within 50pc. We have measured the equivalent width of the H{alpha} emission line. Our targets show an increase in chromospheric activity from early to midspectral types, with a peak in activity around M5. Using the count rate and hardness ratios obtained from the ROSAT catalog, we have derived the X-ray luminosities. Our stars display a "saturation-type" relation between the chromospheric and coronal activity. The relation is such that log(LX/Lbol) remains "saturated" at a value of approximately -3 for varying H{alpha} equivalent width. We have found 568 matches in the USNO-B catalog and have derived the tangential velocities for these stars. There is a slight trend of decreasing chromospheric activity with age, such that the stars with higher vtan have lower H{alpha} equivalent widths. The coronal emission, however, remains saturated at a value of log(LX/Lbol)~-3 for varying tangential velocities, suggesting that the coronal activity remains saturated with age. We do not find any break in the saturation-type relation at the spectral type at which stars become fully convective (~M3.5). Most of the stars in our sample show more coronal emission than the dMe stars in the Hyades and Praesepe and have v_tan_<40km/s, suggesting a young population.
4287. New minima timings and RVs for 3 eclipsing binaries
ID:
ivo://CDS.VizieR/J/AJ/153/36
Title:
New minima timings and RVs for 3 eclipsing binaries
Short Name:
J/AJ/153/36
Date:
21 Oct 2021
Publisher:
CDS
Description:
Eclipsing binaries remain crucial objects for our understanding of the universe. In particular, those that are components of multiple systems can help us solve the problem of the formation of these systems. Analysis of the radial velocities together with the light curve produced for the first time precise physical parameters of the components of the multiple systems V773 Cas, QS Aql, and BR Ind. Their visual orbits were also analyzed, which resulted in slightly improved orbital elements. What is typical for all these systems is that their most dominant source is the third distant component. The system V773 Cas consists of two similar G1-2V stars revolving in a circular orbit and a more distant component of the A3V type. Additionally, the improved value of parallax was calculated to be 17.6 mas. Analysis of QS Aql resulted in the following: the inner eclipsing pair is composed of B6V and F1V stars, and the third component is of about the B6 spectral type. The outer orbit has high eccentricity of about 0.95, and observations near its upcoming periastron passage between the years 2038 and 2040 are of high importance. Also, the parallax of the system was derived to be about 2.89 mas, moving the star much closer to the Sun than originally assumed. The system BR Ind was found to be a quadruple star consisting of two eclipsing K dwarfs orbiting each other with a period of 1.786 days; the distant component is a single-lined spectroscopic binary with an orbital period of about 6 days. Both pairs are moving around each other on their 148 year orbit.
4288. New M31 star cluster candidates
ID:
ivo://CDS.VizieR/J/A+A/658/A51
Title:
New M31 star cluster candidates
Short Name:
J/A+A/658/A51
Date:
22 Feb 2022
Publisher:
CDS
Description:
Identification of new star cluster candidates in M 31 is fundamental for the study of the M 31 stellar cluster system. The machine-learning method convolutional neural network (CNN) is an efficient algorithm for searching for new M 31 star cluster candidates from tens of millions of images from wide-field photometric surveys. We search for new M 31 cluster candidates from the high-quality g- and i-band images of 21 245 632 sources obtained from the Pan-Andromeda Archaeological Survey (PAndAS) through a CNN. We collected confirmed M 31 clusters and noncluster objects from the literature as our training sample. Accurate double-channel CNNs were constructed and trained using the training samples. We applied the CNN classification models to the PAndAS g- and i-band images of over 21 million sources to search new M 31 cluster candidates. The CNN predictions were finally checked by five experienced human inspectors to obtain high-confidence M 31 star cluster candidates. After the inspection, we identified a catalogue of 117 new M 31 cluster candidates. Most of the new candidates are young clusters that are located in the M 31 disk. Their morphology, colours, and magnitudes are similar to those of the confirmed young disk clusters. We also identified eight globular cluster candidates that are located in the M 31 halo and exhibit features similar to those of confirmed halo globular clusters. The projected distances to the M 31 centre for three of them are larger than 100kpc.
4289. New nearby stars in the LEHPMS
ID:
ivo://CDS.VizieR/J/A+A/421/643
Title:
New nearby stars in the LEHPMS
Short Name:
J/A+A/421/643
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a systematic search for new neighbourhood stars among the Liverpool-Edinburgh high proper motion survey which we cross-identified with the DENIS survey. Their high proper motions ensure that they are not giant stars. The distances are estimated using DENIS photometry and we found that 100 stars probably lie within 25 parsecs from the Sun. They are mostly M-dwarfs, and 10 are probably white dwarfs. This is the first distance estimate for 84 stars among them. 10 stars are estimated to be closer than 15 parsecs. In addition, one star, DENIS J2343155-241047, could also lie within 15pc if it belongs to the halo.
4290. New nearby white dwarf systems
ID:
ivo://CDS.VizieR/J/AJ/134/252
Title:
New nearby white dwarf systems
Short Name:
J/AJ/134/252
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present spectra for 33 previously unclassified white dwarf systems brighter than V=17, primarily in the southern hemisphere. Of these new systems, 26 are DA, 4 are DC, 2 are DZ, and 1 is DQ. We suspect that three of these systems are unresolved double degenerates. We obtained VRI photometry for these 33 objects, as well as for 23 known white dwarf systems without trigonometric parallaxes, also primarily in the southern hemisphere. For the 56 objects, we converted the photometry values to fluxes and fit them to a spectral energy distribution using the spectroscopy to determine which model to use (i.e., pure hydrogen, pure helium, or metal-rich helium), resulting in estimates of Teff and distance.