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4081. M-type star magnetic activities from LAMOST & Kepler
ID:
ivo://CDS.VizieR/J/ApJS/243/28
Title:
M-type star magnetic activities from LAMOST & Kepler
Short Name:
J/ApJS/243/28
Date:
21 Oct 2021
Publisher:
CDS
Description:
We performed a statistical study of magnetic activities of M-type stars by combining the spectra of LAMOST DR5 with light curves from the Kepler and K2 missions. We mainly want to study the relationship between chromospheric activity and flares, and their relations of magnetic activity and rotation period. We have obtained the maximum catalog of 516688 M-type stellar spectra of 480912 M stars from LAMOST-DR5 and calculated their equivalent widths of chromospheric activity indicators (H{alpha}, H{beta}, H{gamma}, H{delta}, CaII H&K, and HeI D3). Using the H{alpha} indicator, 40464 spectra of 38417 M stars show chromospheric activity, and 1791 of these 5499 M-type stars with repeated observations have H{alpha} variability. We used an automatic detection plus visual inspection method to detect 17432 flares on 8964 M-type stars from the catalog by cross-matching LAMOST DR5 and the Kepler and K2 databases. We used the Lomb-Scargle method to calculate their rotation periods. We find that the flare frequency is consistent with the ratio of activities of these chromospheric activity indicators as a function of spectral type in M0-M3. We find the equivalent widths of H{alpha} and CaII H have a significant statistical correlation with the flare amplitude in M-type stars. We confirm that the stellar flare is affected by both the stellar magnetic activity and the rotation period. Finally, using the H{alpha} equivalent width equal to 0.75{AA} and using the rotation period equal to 10 days as the threshold for the M-type stellar flare time frequency are almost equivalent.
4082. M-type stars in LAMOST DR5
ID:
ivo://CDS.VizieR/J/ApJS/244/8
Title:
M-type stars in LAMOST DR5
Short Name:
J/ApJS/244/8
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new catalogs of M giant and M dwarf stars from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) data release 5 (DR5). In total, 39796 M giants and 501152 M dwarfs are identified from the classification pipeline. The template-fitting results contain M giants with 7 temperature subtypes from M0 to M6, M dwarfs with 18 temperature subtypes from K7.0 to M8.5, and 12 metallicity subclasses from dMr to usdMp. We cross-matched our M-type catalog with the Two Micron All-Sky Survey (2MASS) and Wide-field Infrared Survey Explorer (WISE) catalog to obtain infrared magnitude and colors. Adopting the distances derived from the parallaxes in Gaia DR2, the M_G_ versus (G_bp_-G_rp_)_0_ diagram shows that there are also early-type stars and white dwarf-M dwarf binaries included in our M-type stars sample, with a contamination rate of about 4.6% for M giants and 0.48% for M dwarfs. We found that CaH spectral indices are an efficient selection criteria for carbon stars. A total of 289 carbon stars were identified from the M giants sample, and further confirmed by LAMOST spectra.
4083. M4 UBV color-magnitude diagrams
ID:
ivo://CDS.VizieR/J/AJ/124/1486
Title:
M4 UBV color-magnitude diagrams
Short Name:
J/AJ/124/1486
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present UBV color-magnitude diagrams (CMDs) for the globular cluster M4. The CMDs show a sequence of four luminous blue stars (V<20, U-V<-0.6), which appear to be cluster hot subdwarfs. We present spectra for the three brightest ones. We also note the presence of a population of faint blue objects, likely to be hot, young white dwarfs belonging to the cluster. We have selected five objects above V=22mag, bright enough for follow-up ground-based spectroscopy, and present their coordinates and finding charts. We show a spectrum for variable V46, which suggests that it is a hot subdwarf, along with a new light curve obtained with the ISIS image subtraction package. The light curve is unstable, but only one period of variability is apparent. Two new variables have been discovered, both located on the cluster red giant branch. We also present a differential E(B-V) reddening map and a fiducial sequence for the main sequence, subgiant branch, and red giant branch on the V/B-V CMD for a selected region with uniform reddening. Based on a comparison with the M5 fiducial sequence, we obtain a reddening estimate of E(B-V)=0.41mag toward M4, consistent with previous determinations.
4084. M30 UBV photometry
ID:
ivo://CDS.VizieR/J/AJ/116/1757
Title:
M30 UBV photometry
Short Name:
J/AJ/116/1757
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present F555W (V), F439W (B), and F336W (U) photometry of 9507 stars in the central 2' of the dense, post-core-collapse cluster M30 (NGC 7099) derived from Hubble Space Telescope Wide Field Planetary Camera 2 images. These data are used to study the mix of stellar populations in the central region of the cluster. Forty-eight blue straggler stars are identified; they are found to be strongly concentrated toward the cluster center. The specific frequency of blue stragglers, F_BSS_=N(BSS)/N(V<V_HB_+2), is 0.25+/-0.05 in the inner region of M30 (r<20"), significantly higher than the frequency found in other clusters: F_BSS_=0.05-0.15. The shape of M30's blue straggler luminosity function resembles the prediction of the collisional formation model, and is inconsistent with the binary merger model of Bailyn & Pinsonneault (1995ApJ...439..705B). An unusually blue star (B=18.6, B-V=-0.97), possibly a cataclysmic variable based on its color, is found about 1.2" from the crowded cluster center; the photometric uncertainty for this star is large, however, because of the presence of a very close neighbor. Bright red giant stars (B<16.6) appear to be depleted by a factor of 2-3 in the inner r<10" relative to fainter giants, subgiants, and main-sequence turnoff stars (95% significance). We confirm that there is a radial gradient in the color of the overall cluster light, going from B-V~0.82 at r~1' to B-V~0.45 in the central 10". The central depletion of the bright red giants is responsible for about half of the observed color gradient; the rest of the gradient is caused by the relative underabundance of faint red main-sequence stars near the cluster center (presumably a result of mass segregation). The luminosity function of M30's evolved stars does not match the luminosity function shape derived from standard stellar evolutionary models: the ratio of the number of bright giants to the number of turnoff stars in the cluster is 30% higher than predicted by the model (3.8{sigma} effect), roughly independent of red giant brightness over the range M_V_=-2 to +2.
4085. M31 UBVR photometry
ID:
ivo://CDS.VizieR/J/ApJ/324/172
Title:
M31 UBVR photometry
Short Name:
J/ApJ/324/172
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report deep UBVR CCD photometry of stars in a portion of an arm of M 31, 20kpc southwest of the nucleus. The color-magnitude diagram shows a main sequence that reaches from Mv=-0.7 (at our photometric limit) to Mv=-6.2 and a well-populated giant region. The R, B-R diagram separates the stars rather clearly into three groups, the main sequence, intermediate-color stars (which include the brighter foreground stars), and the red giants. Reddening is found to average E(B-V)=0.13+/-0.04. To determine a reliable luminosity function, we have eliminated foreground contamination and have evaluated our sample completeness, using a large number of artificial stars in the DAOPHOT reduction routine. The corrected luminosity function, which extends from Mv=-5 to -1, has a logarithmic slope of 0.57+/-0.07 for all stars and 0.53+/-0.06 for main-sequence stars only. This value is similar to that reported for galaxies in general (Freedman 1985ApJ...299...74F and 1986, IAUS 116, 61).
4086. Multi-band light curve of WASP-36
ID:
ivo://CDS.VizieR/J/MNRAS/459/1393
Title:
Multi-band light curve of WASP-36
Short Name:
J/MNRAS/459/1393
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present broad-band photometry of five transits in the planetary system WASP-36, totaling 17 high-precision light curves. Four of the transits were simultaneously observed in four passbands (g', r', i', z'), using the telescope-defocussing technique, and achieving scatters of less than 1 mmag per observation. We used these data to improve the measured orbital and physical properties of the system, and obtain an optical transmission spectrum of the planet. We measured a decreasing radius from bluer to redder passbands with a confidence level of more than 5 sigma. The radius variation is roughly 11 pressure scale heights between the g' and the z' bands. This is too strong to be Rayleigh scattering in the planetary atmosphere, and implies the presence of a species which absorbs strongly at bluer wavelengths.
4087. Multi-band magnitudes for W UMa EB* candidates
ID:
ivo://CDS.VizieR/J/ApJ/859/140
Title:
Multi-band magnitudes for W UMa EB* candidates
Short Name:
J/ApJ/859/140
Date:
21 Oct 2021
Publisher:
CDS
Description:
W Ursa Majoris (W UMa)-type contact binary systems (CBs) are useful statistical distance indicators because of their large numbers. Here, we establish (orbital) period-luminosity relations (PLRs) in 12 optical to mid-infrared bands (GBVRIJHKsW1W2W3W4) based on 183 nearby W UMa-type CBs with accurate Tycho-Gaia parallaxes. The 1{sigma} dispersion of the PLRs decreases from optical to near- and mid-infrared wavelengths. The minimum scatter, 0.16mag, implies that W UMa-type CBs can be used to recover distances to 7% precision. Applying our newly determined PLRs to 19 open clusters containing W UMa-type CBs demonstrates that the PLR and open cluster CB distance scales are mutually consistent to within 1%. Adopting our PLRs as secondary distance indicators, we compiled a catalog of 55603 CB candidates, of which 80% have distance estimates based on a combination of optical, near-infrared, and mid- infrared photometry. Using Fourier decomposition, 27318 high-probability W UMa-type CBs were selected. The resulting 8% distance accuracy implies that our sample encompasses the largest number of objects with accurate distances within a local volume with a radius of 3kpc available to date. The distribution of W UMa-type CBs in the Galaxy suggests that in different environments, the CB luminosity function may be different: larger numbers of brighter (longer-period) W UMa-type CBs are found in younger environments.
4088. Multi-band photometry catalogue of 185 DSFGs
ID:
ivo://CDS.VizieR/J/A+A/641/A129
Title:
Multi-band photometry catalogue of 185 DSFGs
Short Name:
J/A+A/641/A129
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dusty high-z galaxies are extreme objects with high star formation rates (SFRs) and luminosities. Characterising the properties of this population and analysing their evolution over cosmic time is key to understanding galaxy evolution in the early Universe. We select a sample of high-z dusty star-forming galaxies (DSFGs) and evaluate their position on the main sequence (MS) of star-forming galaxies, the well-known correlation between stellar mass and SFR. We aim to understand the causes of their high star formation and quantify the percentage of DSFGs that lie above the MS. We adopted a multi-wavelength approach with data from optical to submillimetre wavelengths from surveys at the North Ecliptic Pole (NEP) to study a submillimetre sample of high-redshift galaxies. Two submillimetre selection methods were used, including: sources selected at 850um with the Sub-millimetre Common-User Bolometer Array 2) SCUBA-2 instrument and Herschel-Spectral and Photometric Imaging Receiver (SPIRE) selected sources (colour-colour diagrams and 500um risers), finding that 185 have good multi-wavelength coverage. The resulting sample of 185 high-z candidates was further studied by spectral energy distribution (SED) fitting with the CIGALE fitting code. We derived photometric redshifts, stellar masses, SFRs, and additional physical parameters, such as the infrared luminosity and active galactic nuclei (AGN) contribution. We find that the Herschel-SPIRE selected DSFGs generally have higher redshifts (z=2.57^+0.08^_-0.09_) than sources that are selected solely by the SCUBA-2 method (z=1.45^+0.21^_-0.06_). We find moderate SFRs (797^+108^_-50_M_{sun}/yr}), which are typically lower than those found in other studies. We find that the different results in the literature are, only in part, due to selection effects, as even in the most extreme cases, SFRs are still lower than a few thousand solar masses per year. The difference in measured SFRs affects the position of DSFGs on the MS of galaxies; most of the DSFGs lie on the MS (60%). Finally, we find that the star formation efficiency (SFE) depends on the epoch and intensity of the star formation burst in the galaxy; the later the burst, the more intense the star formation. We discuss whether the higher SFEs in DSFGs could be due to mergers.
4089. Multi-band photometry of GRB 130427A
ID:
ivo://CDS.VizieR/J/ApJ/781/37
Title:
Multi-band photometry of GRB 130427A
Short Name:
J/ApJ/781/37
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present multiwavelength observations of the afterglow of GRB130427A, the brightest (in total fluence) Gamma-Ray Burst (GRB) of the past 29yr. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z=0.340, indicating that its unprecedented brightness is primarily the result of its relatively close proximity to Earth; the intrinsic luminosities of both the GRB and its afterglow are not extreme in comparison to other bright GRBs. We present a large suite of multiwavelength observations spanning from 300s to 130days after the burst and demonstrate that the afterglow shows relatively simple, smooth evolution at all frequencies, with no significant late-time flaring or rebrightening activity. The entire data set from 1GHz to 10GeV can be modeled as synchrotron emission from a combination of reverse and forward shocks in good agreement with the standard afterglow model, providing strong support to the applicability of the underlying theory and clarifying the nature of the GeV emission observed to last for minutes to hours following other very bright GRBs. A tenuous, wind-stratified circumburst density profile is required by the observations, suggesting a massive-star progenitor with a low mass-loss rate, perhaps due to low metallicity. GRBs similar in nature to GRB 130427A, inhabiting low-density media and exhibiting strong reverse shocks, are probably not uncommon but may have been difficult to recognize in the past owing to their relatively faint late-time radio emission; more such events should be found in abundance by the new generation of sensitive radio and millimeter instruments.
4090. Multi-band photometry of GRB 110205A + 110213A
ID:
ivo://CDS.VizieR/J/ApJ/743/154
Title:
Multi-band photometry of GRB 110205A + 110213A
Short Name:
J/ApJ/743/154
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present rich, early-time, multiband data sets for two Swift events, GRB 110205A and GRB 110213A. The former shows optical emission since the early stages of the prompt phase, followed by the steep rising in flux up to ~1000s after the burst (t^-{alpha}^ with {alpha}=-6.13+/-0.75). We discuss this feature in the context of the reverse-shock scenario and interpret the following single power-law decay as being forward-shock dominated. Polarization measurements, obtained with the RINGO2 instrument mounted on the Liverpool Telescope, also provide hints on the nature of the emitting ejecta. The latter event, instead, displays a very peculiar optical to near-infrared light curve, with two achromatic peaks. In this case, while the first peak is probably due to the onset of the afterglow, we interpret the second peak to be produced by newly injected material, signifying a late-time activity of the central engine.