- ID:
- ivo://CDS.VizieR/J/A+A/622/A133
- Title:
- M45, M44 and M67 flare stars
- Short Name:
- J/A+A/622/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The presence and strength of a stellar magnetic field and activity is rooted in a star's fundamental parameters such as mass and age. Can flares serve as an accurate stellar "clock"? To explore if we can quantify an activity-age relation in the form of a flaring-age relation, we measured trends in the flaring rates and energies for stars with different masses and ages. We investigated the time- domain photometry provided by Kepler's follow-up mission K2 and searched for flares in three solar metallicity open clusters with well-known ages, M45 (0.125Gyr), M44 (0.63Gyr), and M67 (4.3Gyr). We updated and employed the automated flare finding and analysis pipeline Appaloosa, originally designed for Kepler. We introduced a synthetic flare injection and recovery subroutine to ascribe detection and energy recovery rates for flares in a broad energy range for each light curve. We collected a sample of 1761 stars, mostly late-K to mid-M dwarfs and found 751 flare candidates with energies ranging from 4x10^32^erg to 6x10^34^erg, of which 596 belong to M45, 155 to M44, and none to M67. We find that flaring activity depends both on Teff, and age. But all flare frequency distributions have similar slopes with alpha from 2.0 to 2.4, supporting a universal flare generation process. We discuss implications for the physical conditions under which flares occur, and how the sample's metallicity and multiplicity affect our results.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/553/A54
- Title:
- M100 (NGC4321) HII region IRAC photometry
- Short Name:
- J/A+A/553/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We systematically study the relations between the H{alpha} luminosity and the near-IR luminosity and temperature of a set of selected HII regions in the disc of M100. By using the technique of cross-reference between the optical H{alpha} image (the catalogue of HII regions in M100 and the Spitzer IRAC images, we locate the selected HII regions in the IRAC image frames. By using the chi-squared non-linear fitting technique, we estimate the IRAC-3-band colour temperature T_col(IRAC)_ of selected HII regions, and calculate their near-IR luminosities.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A12
- Title:
- M5 (NGC5904) UBVRI photometry
- Short Name:
- J/A+A/558/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar evolution is modified if energy is lost in a "dark channel" similar to neutrino emission. Comparing modified stellar evolution sequences with observations provides some of the most restrictive limits on axions and other hypothetical low-mass particles and on non-standard neutrino properties. In particular, a putative neutrino magnetic dipole moment {mu}_{nu}_ enhances the plasmon decay process, postpones helium ignition in low-mass stars, and therefore extends the red-giant branch (RGB) in globular clusters (GCs). The brightness of the tip of the RGB (TRGB) remains the most sensitive probe for {mu}_{nu}_ and we revisit this argument from a modern perspective. Based on a large set of archival observations, we provide high-precision photometry for the Galactic GC M5 (NGC 5904) and carefully determine its TRGB position.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/113
- Title:
- Molecular clouds with GLIMPSE/MIPSGAL data
- Short Name:
- J/ApJ/839/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the star-formation (SF) law in 12 Galactic molecular clouds with ongoing high-mass star-formation (HMSF) activity, as traced by the presence of a bright IRAS source and other HMSF tracers. We define the molecular cloud (MC) associated with each IRAS source using ^13^CO line emission, and count the young stellar objects (YSOs) within these clouds using GLIMPSE and MIPSGAL 24{mu}m Spitzer databases. The masses for high-luminosity YSOs (L_bol_>10L_{sun}_) are determined individually using pre-main-sequence evolutionary tracks and the evolutionary stages of the sources, whereas a mean mass of 0.5M_{sun}_ was adopted to determine the masses in the low-luminosity YSO population. The star-formation rate surface density ({Sigma}SFR) corresponding to a gas surface density ({Sigma}gas) in each MC is obtained by counting the number of the YSOs within successive contours of ^13^CO line emission. We find a break in the relation between {Sigma}SFR and {Sigma}gas, with the relation being a power law ({Sigma}SFR{propto}{Sigma}gas^N^) with the index N varying between 1.4 and 3.6 above the break. The {Sigma}gas at the break is between 150-360M_{sun}_/pc^2^ for the sample clouds, which compares well with the threshold gas density found in recent studies of Galactic star-forming regions. Our clouds treated as a whole lie between the Kennicutt relation and the linear relation for Galactic and extra-galactic dense star-forming regions. We find a tendency for the high- mass YSOs to be found preferentially in dense regions at densities higher than 1200M_{sun}_/pc^2^ (~0.25g/cm^2^).
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/675
- Title:
- Monitoring low-mass stars in NGC 2362
- Short Name:
- J/MNRAS/384/675
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the results of a time-series photometric survey of NGC 2362, carried out using the CTIO 4-m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 271(*) candidate cluster members over the mass range 0.1~<M/M_{sun}_<~1.2. The rotation period distributions show a clear mass-dependent morphology, qualitatively similar to that in NGC 2264, as would be expected from the age of this cluster. Using models of angular momentum evolution, we show that angular momentum losses over the ~1-5Myr age range appear to be needed in order to reproduce the evolution of the slowest rotators in the sample from the ONC to NGC 2362, as found by many previous studies. By incorporating Spitzer IRAC mid-infrared (mid-IR) measurements, we found that three to four objects showing mid-IR excesses indicative of the presence of circumstellar discs were all slow rotators, as would be expected in the disc regulation paradigm for early pre-main-sequence angular momentum evolution, but this result is not statistically significant at present, given the extremely limited sample size. (*) The abstract indicates 271 clusters, but the actual number is 272.
- ID:
- ivo://CDS.VizieR/J/AJ/147/82
- Title:
- Monitoring of disk-bearing stars in NGC 2264
- Short Name:
- J/AJ/147/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Coordinated Synoptic Investigation of NGC 2264, a continuous 30 day multi-wavelength photometric monitoring campaign on more than 1000 young cluster members using 16 telescopes. The unprecedented combination of multi-wavelength, high-precision, high-cadence, and long-duration data opens a new window into the time domain behavior of young stellar objects. Here we provide an overview of the observations, focusing on results from Spitzer and CoRoT. The highlight of this work is detailed analysis of 162 classical T Tauri stars for which we can probe optical and mid-infrared flux variations to 1% amplitudes and sub-hour timescales. We present a morphological variability census and then use metrics of periodicity, stochasticity, and symmetry to statistically separate the light curves into seven distinct classes, which we suggest represent different physical processes and geometric effects. We provide distributions of the characteristic timescales and amplitudes and assess the fractional representation within each class. The largest category (>20%) are optical "dippers" with discrete fading events lasting ~1-5 days. The degree of correlation between the optical and infrared light curves is positive but weak; notably, the independently assigned optical and infrared morphology classes tend to be different for the same object. Assessment of flux variation behavior with respect to (circum)stellar properties reveals correlations of variability parameters with H{alpha} emission and with effective temperature. Overall, our results point to multiple origins of young star variability, including circumstellar obscuration events, hot spots on the star and/or disk, accretion bursts, and rapid structural changes in the inner disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/101
- Title:
- Monoceros Overdensity deep imaging with Subaru
- Short Name:
- J/ApJ/754/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive distance, density, and metallicity distribution of the stellar Monoceros Overdensity (MO) in the outer Milky Way, based on deep imaging with the Subaru Telescope. We applied color-magnitude diagram fitting techniques in three stripes at galactic longitudes, l~130{deg}, 150{deg}, 170{deg}, and galactic latitudes, +15{deg}<=b<=+25{deg}. The MO appears as a wall of stars at a heliocentric distance of ~10.1+/-0.5kpc across the observed longitude range with no distance change. The MO stars are more metal-rich ([Fe/H]~-1.0) than the nearby stars at the same latitude. These data are used to test three different models for the origin of the MO: a perturbed disk model, which predicts a significant drop in density adjacent to the MO that is not seen; a basic flared disk model, which can give a good match to the density profile but the MO metallicity implies the disk is too metal-rich to source the MO stars; and a tidal stream model, which, from the literature, brackets the distances and densities we derive for the MO, suggesting that a model can be found that would fully fit the MO data. Further data and modeling will be required to confirm or rule out the MO feature as a stream or as a flaring of the disk.
- ID:
- ivo://CDS.VizieR/J/AJ/140/533
- Title:
- Morphologies of selected AGN
- Short Name:
- J/AJ/140/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the optical morphologies of candidate active galaxies identified at radio, X-ray, and mid-infrared wavelengths. We use the Advanced Camera for Surveys General Catalog (ACS-GC) to identify 372, 1360, and 1238 active galactic nucleus (AGN) host galaxies from Very Large Array, XMM-Newton, and Spitzer Space Telescope observations of the COSMOS field, respectively. We investigate both quantitative (GALFIT) and qualitative (visual) morphologies of these AGN host galaxies, split by brightness in their selection band.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/3015
- Title:
- Morphologies of S4G galaxies
- Short Name:
- J/MNRAS/444/3015
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue and images of visually detected features, such as asymmetries, extensions, warps, shells, tidal tails, polar rings, and obvious signs of mergers or interactions, in the faint outer regions (at and outside of R_25_) of nearby galaxies. This catalogue can be used in future quantitative studies that examine galaxy evolution due to internal and external factors. We are able to reliably detect outer region features down to a brightness level of 0.03MJy/sr/pixel at 3.6{mu}m in the Spitzer Survey of Stellar Structure in Galaxies (S4G). We also tabulate companion galaxies. We find asymmetries in the outer isophotes in 22+/-1% of the sample. The asymmetry fraction does not correlate with galaxy classification as an interacting galaxy or merger remnant, or with the presence of companions. We also compare the detected features to similar features in galaxies taken from cosmological zoom re-simulations. The simulated images have a higher fraction (33%) of outer disc asymmetries, which may be due to selection effects and an uncertain star formation threshold in the models. The asymmetries may have either an internal (e.g. lopsidedness due to dark halo asymmetry) or external origin.
- ID:
- ivo://CDS.VizieR/J/AJ/146/151
- Title:
- Morphology catalog of nearby galaxies from SDSS DR7
- Short Name:
- J/AJ/146/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the statistical properties of a volume-limited sample of 7429 nearby (z=0.033-0.044) galaxies from the Sloan Digital Sky Survey Data Release 7. Our database includes morphology distribution as well as the structural and spectroscopic properties of each morphology type based on the recent remeasurements of spectral line strengths by Oh and collaborators. Our database does not include galaxies that are apparently smaller and flatter because morphology classification of them turned out to be difficult. Our statistics confirmed the up-to-date knowledge of galaxy populations, e.g., correlations between morphology and line strengths as well as the derived ages. We hope that this database will be useful as a reference.
