Search

Start Over Subject photometry
3361. K-M stars of class I candidate RSGs in Gaia DR2
ID:
ivo://CDS.VizieR/J/AJ/158/20
Title:
K-M stars of class I candidate RSGs in Gaia DR2
Short Name:
J/AJ/158/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate individual distances and luminosities of a sample of 889 nearby candidate red supergiants (RSGs) with reliable parallaxes ({omega}/{sigma}_{omega}_>4 and RUWE<2.7) from Gaia Data Release 2 (DR2, Cat. I/345). The sample was extracted from the historical compilation of spectroscopically derived spectral types by Skiff (Cat. B/mk), and consists of K-M stars that are listed with class I at least once. The sample includes well-known RSGs from Humphreys (1978ApJS...38..309H), Elias et al. (1985ApJS...57...91E), Jura & Kleinmann (1990ApJS...73..769J), and Levesque et al. (2005ApJ...628..973L). Infrared and optical measurements from the Two Micron All Sky Survey, Catalog of Infrared Observations (CIO), Midcourse Space Experiment, Wide-field Infrared Survey Explorer, MIPSGAL, Galactic Legacy Infrared Midplane Extraordinaire (GLIMPSE), and The Naval Observatory Merged Astrometric Dataset catalogs allow us to estimate the stellar bolometric magnitudes. We analyze the stars in the luminosity versus effective temperature plane and confirm that 43 sources are highly probably RSGs with M_bol_< -7.1 mag. Of the stars in the sample, 43% have masses >7 M_{sun}_. Another ~30% of the sample consists of giant stars.
3362. KMT-2018-BLG-1025Lb I light curve
ID:
ivo://CDS.VizieR/J/A+A/649/A90
Title:
KMT-2018-BLG-1025Lb I light curve
Short Name:
J/A+A/649/A90
Date:
22 Feb 2022
Publisher:
CDS
Description:
We aim to find missing microlensing planets hidden in the unanalyzed lensing events of previous survey data. For this purpose, we conduct a systematic inspection of high-magnification microlensing events, with peak magnifications Apeak>~30, in the data collected from high-cadence surveys in and before the 2018 season. From this investigation, we identify an anomaly in the lensing light curve of the event KMT-2018-BLG-1025. The analysis of the light curve indicates that the anomaly is caused by a very low mass-ratio companion to the lens. We identify three degenerate solutions, in which the ambiguity between a pair of solutions (solutions B) is caused by the previously known close-wide degeneracy, and the degeneracy between these and the other solution (solution A) is a new type that has not been reported before. The estimated mass ratio between the planet and host is q~0.8x10^-4^ for the solution A and q~1.6x10^-4^ for the solutions B. From the Bayesian analysis conducted with measured observables, we estimate that the masses of the planet and host and the distance to the lens are (Mp, Mh, DL)~(6.1M_{sun}_, 0.22M_Earth_, 6.7kpc) for the solution A and ~(4.4M_{sun}_, 0.08M_Earth_, 7.5kpc) for the solutions B. The planet mass is in the category of a super-Earth regardless of the solutions, making the planet the eleventh super-Earth planet, with masses lying between those of Earth and the Solar system's ice giants, discovered by microlensing.
3363. KMTNet LCs of ~1000 main-belt asteroids
ID:
ivo://CDS.VizieR/J/ApJS/237/19
Title:
KMTNet LCs of ~1000 main-belt asteroids
Short Name:
J/ApJS/237/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present VRI spectrophotometry of 1003 main-belt asteroids (MBAs) observed with the Sutherland, South Africa node of the Korea Microlensing Telescope Network (KMTNet). All of the observed MBAs were serendipitously captured in KMTNet's large 2{deg}x2{deg} field of view during a separate targeted near-Earth Asteroid study. Our broadband spectrophotometry is reliable enough to distinguish among four asteroid taxonomies and we confidently categorize 836 of the 1003 observed targets as either a S-, C-, X-, or D-type asteroid by means of a machine learning algorithm approach. Our data show that the ratio between S-type MBAs and (C+X+D)-type MBAs, with H magnitudes between 12 and 18 (12km>~diameter>~0.75km), is almost exactly 1:1. Additionally, we report 0.5-3hr (median: 1.3hr) light-curve data for each MBA and we resolve the complete rotation periods and amplitudes for 59 targets. Of the 59 targets, 2 have rotation periods potentially below the theoretical zero-cohesion boundary limit of 2.2hr. We report lower limits for the rotation periods and amplitudes for the remaining targets. Using the resolved and unresolved light curves we determine the shape distribution for this population using a Monte Carlo simulation. Our model suggests a population with an average elongation b/a=0.74+/-0.07 and also shows that this is independent of asteroid size and taxonomy.
3364. KMTNet, MOA and OGLE light curve of KMT-2019-BLG-0371
ID:
ivo://CDS.VizieR/J/AJ/162/17
Title:
KMTNet, MOA and OGLE light curve of KMT-2019-BLG-0371
Short Name:
J/AJ/162/17
Date:
16 Mar 2022 00:13:06
Publisher:
CDS
Description:
We show that the perturbation at the peak of the light curve of microlensing event KMT-2019-BLG-0371 is explained by a model with a mass ratio between the host star and planet of q~0.08. Due to the short event duration (t_E_~6.5days), the secondary object in this system could potentially be a massive giant planet. A Bayesian analysis shows that the system most likely consists of a host star with a mass M_h_=0.09_-0.05_^+0.14^Msun and a massive giant planet with a mass M_p_=7.70_-3.90_^+11.34^M_Jup_. However, the interpretation of the secondary as a planet (i.e., as having M_p_<13M_Jup_) rests entirely on the Bayesian analysis. Motivated by this event, we conduct an investigation to determine which constraints meaningfully affect Bayesian analyses for microlensing events. We find that the masses inferred from such a Bayesian analysis are determined almost entirely by the measured value of {theta}_E_ and are relatively insensitive to other factors such as the direction of the event (l, b), the lens-source relative proper motion {mu}_rel_, or the specific Galactic model prior.
3365. KMTNet & OGLE I-band photometry of KMT-2019-BLG-0842
ID:
ivo://CDS.VizieR/J/AJ/160/255
Title:
KMTNet & OGLE I-band photometry of KMT-2019-BLG-0842
Short Name:
J/AJ/160/255
Date:
09 Mar 2022
Publisher:
CDS
Description:
We report the discovery of a cold planet with a very low planet/host mass ratio of q=(4.09{+/-}0.27)x10^-5^, which is similar to the ratio of Uranus/Sun (q=4.37x10^-5^) in the solar system. The Bayesian estimates for the host mass, planet mass, system distance, and planet-host projected separation are M_host_=0.76{+/-}0.40M{sun}, M_planet_=10.3{+/-}5.5M{Earth}, D_L_=3.3{+/-}1.3kpc, and a{perp}=3.3{+/-}1.4 au, respectively. The consistency of the color and brightness expected from the estimated lens mass and distance with those of the blend suggests the possibility that the most blended light comes from the planet host, and this hypothesis can be established if high-resolution images are taken during the next (2020) bulge season. We discuss the importance of conducting optimized photometry and aggressive follow-up observations for moderately or very high magnification events to maximize the detection rate of planets with very low mass ratios.
3366. KMTNet-SAAO observation of near-Earth asteroids
ID:
ivo://CDS.VizieR/J/AJ/154/162
Title:
KMTNet-SAAO observation of near-Earth asteroids
Short Name:
J/AJ/154/162
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present here VRI spectrophotometry of 39 near-Earth asteroids (NEAs) observed with the Sutherland, South Africa, node of the Korea Microlensing Telescope Network (KMTNet). Of the 39 NEAs, 19 were targeted, but because of KMTNet's large 2{deg}x2{deg} field of view, 20 serendipitous NEAs were also captured in the observing fields. Targeted observations were performed within 44 days (median: 16 days, min: 4 days) of each NEA's discovery date. Our broadband spectrophotometry is reliable enough to distinguish among four asteroid taxonomies and we were able to confidently categorize 31 of the 39 observed targets as either an S-, C-, X-, or D-type asteroid by means of a Machine Learning algorithm approach. Our data suggest that the ratio between "stony" S-type NEAs and "not-stony" (C+X+D)-type NEAs, with H magnitudes between 15 and 25, is roughly 1:1. Additionally, we report ~1 hr light curve data for each NEA, and of the 39 targets, we were able to resolve the complete rotation period and amplitude for six targets and report lower limits for the remaining targets.
3367. Known Galactic field Blazhko stars
ID:
ivo://CDS.VizieR/J/A+A/549/A101
Title:
Known Galactic field Blazhko stars
Short Name:
J/A+A/549/A101
Date:
21 Oct 2021
Publisher:
CDS
Description:
A list of known Galactic field stars exhibiting Blazhko effect containing 242 stars is presented. All the entries including their designations, positions, pulsation, and Blazhko periods were collected from the available literature. The actual values of parameters are given.
3368. Known LT dwarfs in the Gaia DR1
ID:
ivo://CDS.VizieR/J/MNRAS/469/401
Title:
Known LT dwarfs in the Gaia DR1
Short Name:
J/MNRAS/469/401
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify and investigate known ultracool stars and brown dwarfs that are being observed or indirectly constrained by the Gaia mission. These objects will be the core of the Gaia ultracool dwarf sample composed of all dwarfs later than M7 that Gaia will provide direct or indirect information on. We match known L and T dwarfs to the Gaia first data release, the Two Micron All Sky Survey and the Wide-field Infrared Survey Explorer AllWISE survey and examine the Gaia and infrared colours, along with proper motions, to improve spectral typing, identify outliers and find mismatches. There are 321 L and T dwarfs observed directly in the Gaia first data release, of which 10 are later than L7. This represents 45 per cent of all the known LT dwarfs with estimated GaiaG magnitudes brighter than 20.3mag. We determine proper motions for the 321 objects from Gaia and the Two Micron All Sky Survey positions. Combining the Gaia and infrared magnitudes provides useful diagnostic diagrams for the determination of L and T dwarf physical parameters. We then search the Tycho-Gaia astrometric solution, Gaia first data release subset, to find any objects with common proper motions to known L and T dwarfs and a high probability of being related. We find 15 new candidate common proper motion systems.
3369. K2 observations of type Ia supernova SN 2018oh
ID:
ivo://CDS.VizieR/J/ApJ/870/L1
Title:
K2 observations of type Ia supernova SN 2018oh
Short Name:
J/ApJ/870/L1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an exquisite 30minute cadence Kepler (K2) light curve of the Type Ia supernova (SNIa) 2018oh All-Sky Automated Survey for Supernovae (ASASSN-18bt), starting weeks before explosion, covering the moment of explosion and the subsequent rise, and continuing past peak brightness. These data are supplemented by multi-color Panoramic Survey Telescope (Pan-STARRS1) and Rapid Response System 1 and Cerro Tololo Inter-American Observatory 4m Dark Energy Camera (CTIO 4-m DECam) observations obtained within hours of explosion. The K2 light curve has an unusual two-component shape, where the flux rises with a steep linear gradient for the first few days, followed by a quadratic rise as seen for typical supernovae (SNe) Ia. This "flux excess" relative to canonical SNIa behavior is confirmed in our i-band light curve, and furthermore, SN2018oh is especially blue during the early epochs. The flux excess peaks 2.14{+/-}0.04 days after explosion, has a full width at half maximum (FWHM) of 3.12{+/-}0.04 days, a blackbody temperature of T=17500_-9000_^+11500^K, a peak luminosity of 4.3{+/-}0.2x10^37^erg/s, and a total integrated energy of 1.27{+/-}0.01x10^43^erg. We compare SN2018oh to several models that may provide additional heating at early times, including collision with a companion and a shallow concentration of radioactive nickel. While all of these models generally reproduce the early K2 light curve shape, we slightly favor a companion interaction, at a distance of ~2x10^12^cm based on our early color measurements, although the exact distance depends on the uncertain viewing angle. Additional confirmation of a companion interaction in future modeling and observations of SN2018oh would provide strong support for a single-degenerate progenitor system.
3370. KOINet. Study of exoplanet systems via TTVs
ID:
ivo://CDS.VizieR/J/A+A/615/A79
Title:
KOINet. Study of exoplanet systems via TTVs
Short Name:
J/A+A/615/A79
Date:
21 Oct 2021
Publisher:
CDS
Description:
During its four years of photometric observations, the Kepler space telescope detected thousands of exoplanets and exoplanet candidates. One of Kepler's greatest heritages has been the confirmation and characterization of hundreds of multi-planet systems via transit timing variations (TTVs). However, there are many interesting candidate systems displaying TTVs on such long timescales that the existing Kepler observations are of insufficient length to confirm and characterize them by means of this technique. To continue with Kepler's unique work, we have organized the "Kepler Object of Interest Network" (KOINet), a multi-site network formed of several telescopes located throughout America, Europe, and Asia. The goals of KOINet are to complete the TTV curves of systems where Kepler did not cover the interaction timescales well, to dynamically prove that some candidates are true planets (or not), to dynamically measure the masses and bulk densities of some planets, to find evidence for non-transiting planets in some of the systems, to extend Kepler's baseline adding new data with the main purpose of improving current models of TTVs, and to build a platform that can observe almost anywhere on the northern hemisphere, at almost any time. KOINet has been operational since March 2014. Here we show some promising first results obtained from analyzing seven primary transits of KOI-0410.01, KOI-0525.01, KOI-0760.01, and KOI-0902.01, in addition to the Kepler data acquired during the first and second observing seasons of KOINet. While carefully choosing the targets we set demanding constraints on timing precision (at least 1 min) and photometric precision (as good as one part per thousand) that were achieved by means of our observing strategies and data analysis techniques. For KOI-0410.01, new transit data revealed a turnover of its TTVs. We carried out an in-depth study of the system, which is identified in the NASA Data Validation Report as a false positive. Among others, we investigated a gravitationally bound hierarchical triple star system and a planet-star system. While the simultaneous transit fitting of ground- and space-based data allowed for a planet solution, we could not fully reject the three-star scenario. New data, already scheduled in the upcoming 2018 observing season, will set tighter constraints on the nature of the system.