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1961. Passive red spirals in Galaxy Zoo
ID:
ivo://CDS.VizieR/J/MNRAS/405/783
Title:
Passive red spirals in Galaxy Zoo
Short Name:
J/MNRAS/405/783
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the spectroscopic properties and environments of red (or passive) spiral galaxies found by the Galaxy Zoo project. By carefully selecting face-on disc-dominated spirals, we construct a sample of truly passive discs (i.e. they are not dust reddened spirals, nor are they dominated by old stellar populations in a bulge). As such, our red spirals represent an interesting set of possible transition objects between normal blue spiral galaxies and red early types, making up ~6 per cent of late-type spirals. We use optical images and spectra from Sloan Digital Sky Survey to investigate the physical processes which could have turned these objects red without disturbing their morphology.
1962. Passive spiral galaxy cand. multi-phot.
ID:
ivo://CDS.VizieR/J/MNRAS/462/L11
Title:
Passive spiral galaxy cand. multi-phot.
Short Name:
J/MNRAS/462/L11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z<0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph (WiFeS) to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption line spectra with 4000{AA} breaks consistent with an average luminosity-weighted age of 2.3Gyr. Our photometric and IFU spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.
1963. PAST. II. LAMOST-Gaia-Kepler catalog of 35835 stars
ID:
ivo://CDS.VizieR/J/AJ/162/100
Title:
PAST. II. LAMOST-Gaia-Kepler catalog of 35835 stars
Short Name:
J/AJ/162/100
Date:
14 Mar 2022 06:40:51
Publisher:
CDS
Description:
The Kepler telescope has discovered over 4000 planets (candidates) by searching ~200000 stars over a wide range of distance (order of kpc) in our Galaxy. Characterizing the kinematic properties (e.g., Galactic component membership and kinematic age) of these Kepler targets (including the planet candidate hosts) is the first step toward studying Kepler planets in the Galactic context, which will reveal fresh insights into planet formation and evolution. In this paper, the second part of the Planets Across the Space and Time (PAST) series, by combining the data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Gaia and then applying the revised kinematic methods from PAST I, we present a catalog of kinematic properties (i.e., Galactic positions, velocities, and the relative membership probabilities among the thin disk, thick disk, Hercules stream, and the halo) as well as other basic stellar parameters for 35835 Kepler stars. Further analyses of the LAMOST-Gaia-Kepler catalog demonstrate that our derived kinematic age reveals the expected stellar activity-age trend. Furthermore, we find that the fraction of thin (thick) disk stars increases (decreases) with the transiting planet multiplicity (N_p_=0,1,2 and3+) and the kinematic age decreases with N_p_, which could be a consequence of the dynamical evolution of planetary architecture with age. The LAMOST-Gaia-Kepler catalog will be useful for future studies on the correlations between the exoplanet distributions and the stellar Galactic environments as well as ages.
1964. Patterns of color variations in close binaries
ID:
ivo://CDS.VizieR/J/A+A/480/495
Title:
Patterns of color variations in close binaries
Short Name:
J/A+A/480/495
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the first of a series of papers in which we present the results of a long-term photometric monitoring project carried out at Catania Astrophysical Observatory aimed at studying magnetic activity in late-type components of close binary systems, its dependence on global stellar parameters, and its evolution on different time scales from days to years. In this first paper, we present the complete observation dataset and new results of an investigation into the origin of brightness and color variations observed in the well-known magnetically active close binary stars: AR Psc, VY Ari, UX Ari, V711 Tau, EI Eri, V1149 Ori, DH Leo, HU Vir, RS CVn, V775 Her, AR Lac, SZ Psc, II Peg and BY Dra . About 38000 high-precision photoelectric nightly observations in the U, B and V filters are analysed. Correlation and regression analyses of the V magnitude vs. U-B and B-V color variations are carried out and a comparison with model variations for a grid of active region temperature and filling factor values is also performed. We find the existence of two different patterns of color variation. Eight stars in our sample: BY Dr, VY Ari, V775 Her, II Peg, V1149 Ori, HU Vir, EI Eri and DH Leo become redder when they become fainter, as is expected from the presence of active regions consisting of cool spots. The other six stars show the opposite behaviour, i.e. they become bluer when they become fainter. For V711 Tau this behaviour could be explained by the increased relative U- and B- flux contribution by the earlier-type component of the binary system when the cooler component becomes fainter. On the other hand, for AR Psc, UX Ari, RS CVn, SZ Psc and AR Lac the existence of hot photospheric faculae must be invoked. We also found that in single-lined and double-lined binary stars in which the fainter component is inactive or much less active the V magnitude is correlated to B-V and U-B color variations in more than 60% of observation seasons. The correlation is found in less than 40% of observation seasons when the fainter component has a non-negligible level of activity and/or hot faculae are present but they are either spatially or temporally uncorrelated to spots.
1965. PEARS emission-line galaxies
ID:
ivo://CDS.VizieR/J/AJ/135/1624
Title:
PEARS emission-line galaxies
Short Name:
J/AJ/135/1624
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Hubble Space Telescope Advanced Camera for Surveys grism Probing Evolution And Reionization Spectroscopically (PEARS) survey provides a large dataset of low-resolution spectra from thousands of galaxies in the GOODS north and south fields. One important subset of objects in these data is emission-line galaxies (ELGs), and we have investigated several different methods aimed at systematically selecting these galaxies. Here, we present a new methodology and results of a search for these ELGs in the PEARS observations of the Hubble Ultra Deep Field (HUDF) using a 2D detection method that utilizes the observation that many emission lines originate from clumpy knots within galaxies. This 2D line-finding method proves to be useful in detecting emission lines from compact knots within galaxies that might not otherwise be detected using more traditional 1D line-finding techniques.
1966. PEARS emission-line galaxies spectroscopy
ID:
ivo://CDS.VizieR/J/AJ/141/64
Title:
PEARS emission-line galaxies spectroscopy
Short Name:
J/AJ/141/64
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present spectroscopy of 76 emission-line galaxies (ELGs) in Chandra Deep Field South taken with the LDSS3 spectrograph on the Magellan Telescope. These galaxies are selected because they have emission lines with the Advanced Camera for Surveys (ACS) grism data in the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) grism Survey. The ACS grism spectra cover the wavelength range 6000-9700{AA} and most PEARS grism redshifts are based on a single emission line + photometric redshifts from broadband colors; the Magellan spectra cover a wavelength range from 4000{AA} to 9000{AA} and provide a check on redshifts derived from PEARS data.
1967. Period analysis of 7 field RRab stars
ID:
ivo://CDS.VizieR/J/ApJ/863/151
Title:
Period analysis of 7 field RRab stars
Short Name:
J/ApJ/863/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the times of light maximum collected from the GEOS RR Lyrae database and determined from sky surveys, we utilize the O-C method to study the period variations of seven field ab-type RR Lyrae stars. The time coverage of data for most stars is more than 100 years, allowing us to investigate period changes over a large time span. We find that the O-C diagrams for most stars can be described by a combination of cyclic variations and long-term period changes. Assuming the former were caused by the light-travel-time effect, the pulsation and orbital parameters are obtained by the nonlinear fitting. We find that the orbital periods in our sample range from 33 to 78 years, and the eccentricities are relatively higher than the results for other candidates (e>0.6). The minimal masses of the potential companions of XX And, BK Dra, and RY Psc are less than one solar mass, and those of SV Eri, AR Her, and RU Scl are 3.3, 2.1, and 3.4M_{sun}_, respectively. Moreover, we suggest that the companion of AR Her may be a blue straggler that experienced mass transfer or a merger of two stars. The O-C diagram for ST Vir also shows distinct long- term period decrease, and in the O-C residuals, additional quasi-periodic variations that can be described by damped oscillation are found. Combining the data from the literature and our analysis, we plot the log P-AO-C diagram. The distribution of our binary candidates suggests that their period variations are not caused by the Blazhko effect.
1968. Periodic variables in NGC 3766
ID:
ivo://CDS.VizieR/J/A+A/554/A108
Title:
Periodic variables in NGC 3766
Short Name:
J/A+A/554/A108
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze the population of periodic variable stars in the open cluster NGC3766 based on a 7-year multiband monitoring campaign conducted on the 1.2m Swiss Euler telescope at La Silla, Chili. The data reduction, light curve cleaning, and period search procedures, combined with the long observation time line, allowed us to detect variability amplitudes down to the mmag level. The variability properties were complemented with the positions in the color-magnitude and color-color diagrams to classify periodic variable stars into distinct variability types. We find a large population (36 stars) of new variable stars between the red edge of slowly pulsating B (SPB) stars and the blue edge of delta Sct stars, a region in the Hertzsprung-Russell (HR) diagram where no pulsation is predicted to occur based on standard stellar models. The bulk of their periods ranges from 0.1 to 0.7d, with amplitudes between 1 and 4mmag for the majority of them. About 20% of stars in that region of the HR diagram are found to be variable, but the number of members of this new group is expected to be higher, with amplitudes below our mmag detection limit. The properties of this new group of variable stars are summarized and arguments set forth in favor of a pulsation origin of the variability, with g-modes sustained by stellar rotation. Potential members of this new class of low-amplitude periodic (most probably pulsating) A and late-B variables in the literature are discussed. We additionally identify 16 eclipsing binary, 13 SPB, 14 delta Sct, and 12 gamma Dor candidates, as well as 72 fainter periodic variables. All are new discoveries. We encourage searching for this new class of variables in other young open clusters, especially in those hosting a rich population of Be stars.
1969. Periodic variables in NGC 2301
ID:
ivo://CDS.VizieR/J/PASP/121/1188
Title:
Periodic variables in NGC 2301
Short Name:
J/PASP/121/1188
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a search for periodic variables within 4078 time-series light curves and an analysis of the period-color plane for stars in the field of the open cluster NGC 2301. One hundred thirty-eight periodic variables were discovered, of which five are eclipsing binary candidates with unequal minima. The remaining 133 periodic variables appear to consist mainly of late-type stars whose variation is due to rotation modulated by star spot activity. The determined periods range from less than a day to over 14 days and have nearly unreddened B-R colors in the range of 0.8 to 2.8. The Barnes (2003ApJ...586..464B) interpretation of the period-color plane of late type stars is tested with our data. Our data did not show distinct I and C sequences, likely due to nonmember field stars contaminating in the background, as we estimate the total contamination to be 43%. Using different assumptions, the gyrochronological age of the cluster is calculated to be 210+/-25Myr, which falls in the range of age values (164-250Myr) determined by previous studies. Finally, we present evidence which nullifies the earlier suggestion that two of the variable stars in NGC 2301 might be white dwarfs.
1970. Period-luminosity relations of RSGs in M33 & M31
ID:
ivo://CDS.VizieR/J/ApJS/241/35
Title:
Period-luminosity relations of RSGs in M33 & M31
Short Name:
J/ApJS/241/35
Date:
11 Mar 2022
Publisher:
CDS
Description:
Based on previously selected preliminary samples of red supergiants (RSGs) in M33 and M31, the foreground stars and luminous asymptotic giant branch stars are further excluded, which leads to the samples of 717 RSGs in M33 and 420 RSGs in M31. With the time-series data from the Intermediate Palomar Transient Factory survey spanning nearly 2000 days, the period and amplitude of RSGs are analyzed. According to the light-curve characteristics, they are classified into four categories in which 84 and 56 objects in M33 and M31, respectively, are semi-regular variables. For these semi-regular variables, the pulsation mode is identified by comparing with the theoretical model, which yielded 19 (7) sources in the first overtone mode in M33 (M31), and the other 65 (49) RSGs in M33 (M31) in the fundamental mode. The period-luminosity (P-L) relation is analyzed for the RSGs in the fundamental mode. The P-L relation is found to be tight in the infrared, i.e., the Two Mircon All-Sky Survey (2MASS) JHK_S_ bands and the short-wavelength bands of Spitzer. Meanwhile, the inhomogeneous extinction causes the P-L relation scattering in the V band, and the dust emission causes the less tight P-L relation in the Spitzer/[8.0] and [24] bands. The derived P-L relations in the 2MASS/K_S_ band are in agreement with those of RSGs in the Small Magellanic Cloud, the Large Magellanic Cloud, and the Milky Way within the uncertainty range. It is found that the number ratio of RSGs pulsating in the fundamental mode to the first overtone mode increases with metallicity.