Scaling K2. IV. A Uniform Planet Sample for Campaigns 1–8 and 10–18

Abstract We provide the first full K2 transiting exoplanet sample, using photometry from Campaigns 1–8 and 10–18, derived through an entirely automated procedure. This homogeneous planet candidate catalog is crucial to perform a robust demographic analysis of transiting exoplanets with K2. We identify 747 unique planet candidates and 57 multiplanet systems. Of these candidates, 366 have not been previously identified, including one resonant multiplanet system and one system with two short-period gas giants. By automating the construction of this list, measurements of sample biases (completeness and reliability) can be quantified. We carried out a light-curve-level injection/recovery test of artificial transit signals and found a maximum completeness of 61%, a consequence of the significant detrending required for K2 data analysis. Through this operation we attained measurements of the detection efficiency as a function of signal strength, enabling future population analysis using this sample. We assessed the reliability of our planet sample by testing our vetting software EDI-Vetter against inverted transit-free light curves. We estimate that 91% of our planet candidates are real astrophysical signals, increasing up to 94% when limited to the FGKM dwarf stellar population. We also constrain the contamination rate from background eclipsing binaries to less than 5%. The presented catalog, along with the completeness and reliability measurements, enable robust exoplanet demographic studies to be carried out across the fields observed by the K2 mission for the first time.

Download Full-text

SuperWASP variable stars: classifying light curves using citizen science

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab140 ◽

2021 ◽

Vol 502 (1) ◽

pp. 1299-1311

Author(s):

Heidi B Thiemann ◽

Andrew J Norton ◽

Hugh J Dickinson ◽

Adam McMaster ◽

Ulrich C Kolb

Keyword(s):

Variable Stars ◽

Eclipsing Binaries ◽

Light Curves ◽

Data Set ◽

Resultant Data ◽

Sky Survey ◽

Short Period ◽

Contact Binaries ◽

Analysis Of Results

ABSTRACT We present the first analysis of results from the SuperWASP variable stars Zooniverse project, which is aiming to classify 1.6 million phase-folded light curves of candidate stellar variables observed by the SuperWASP all sky survey with periods detected in the SuperWASP periodicity catalogue. The resultant data set currently contains >1 million classifications corresponding to >500 000 object–period combinations, provided by citizen–scientist volunteers. Volunteer-classified light curves have ∼89 per cent accuracy for detached and semidetached eclipsing binaries, but only ∼9 per cent accuracy for rotationally modulated variables, based on known objects. We demonstrate that this Zooniverse project will be valuable for both population studies of individual variable types and the identification of stellar variables for follow-up. We present preliminary findings on various unique and extreme variables in this analysis, including long-period contact binaries and binaries near the short-period cut-off, and we identify 301 previously unknown binaries and pulsators. We are now in the process of developing a web portal to enable other researchers to access the outputs of the SuperWASP variable stars project.

Download Full-text

A survey for high-mass eclipsing binaries

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2953 ◽

2019 ◽

Vol 490 (4) ◽

pp. 5147-5173

Author(s):

F Pozo Nuñez ◽

R Chini ◽

A Barr Domínguez ◽

Ch Fein ◽

M Hackstein ◽

...

Keyword(s):

Eclipsing Binaries ◽

Light Curves ◽

High Mass ◽

System Component ◽

Fundamental Parameters ◽

Average Value ◽

Short Period ◽

Orbital Periods ◽

Photometric Monitoring ◽

Period System

ABSTRACT We report results from a search for Galactic high-mass eclipsing binaries. The photometric monitoring campaign was performed in Sloan r and i with the robotic twin refractor RoBoTT at the Universitätssternwarte Bochum in Chile and complemented by Johnson UBV data. Comparison with the SIMBAD data base reveals 260 variable high-mass stars. Based on well-sampled light curves, we discovered 35 new eclipsing high-mass systems and confirm the properties of six previously known systems. For all objects, we provide the first light curves and determine orbital periods through the Lafler–Kinman algorithm. Apart from GSC 08173-0018 and Pismis 24-13 ($P = 19.47\, d$ and $20.14\, d$) and the exceptional short-period system TYC 6561-1765-1 ($P = 0.71\, d$), all systems have orbital periods between 1 and 9 d. We model the light curves of 26 systems within the framework of the Roche geometry and calculate fundamental parameters for each system component. The Roche lobe analysis indicates that 14 systems have a detached geometry, while 12 systems have a semidetached geometry; seven of them are near-contact systems. The deduced mass ratios q = M2/M1 reach from 0.4 to 1.0 with an average value of 0.8. The similarity of masses suggests that these high-mass binaries were created during the star formation process rather than by tidal capture.

Download Full-text

Barlenses in the CALIFA survey: Combining photometric and stellar population analyses

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833138 ◽

2018 ◽

Vol 618 ◽

pp. A34 ◽

Cited By ~ 3

Author(s):

E. Laurikainen ◽

H. Salo ◽

J. Laine ◽

J. Janz

Keyword(s):

Stellar Population ◽

Population Analysis ◽

Sloan Digital Sky Survey ◽

Central Component ◽

Time Period ◽

Stellar Ages ◽

Sky Survey ◽

First Time ◽

Field Area ◽

Integral Field

Aims: It is theoretically predicted that, at low galaxy inclinations, boxy/peanut bar components have a barlens appearance of a round central component embedded in the narrow bar. We investigate barlenses in the Calar Alto Legacy Integral Field Area (CALIFA) survey galaxies, studying their morphologies, stellar populations, and metallicities. We show that, when present, barlenses account for a significant portion of light of photometric bulges, i.e., the excess light on top of the disks, which highlights the importance of bars in accumulating central galaxy mass concentrations in the cosmic timescale. Methods: We made multi-component decompositions for a sample of 46 barlens galaxies drawn from the CALIFA survey, where M⋆/M⊙ = 109.7 − 1011.4 and z = 0.005 − 0.03. Unsharp masks of the Sloan Digital Sky Survey (SDSS) r′-band mosaics were used to identify the boxy/peanut or X-shaped features. Barlenses are identified in the images using our simulation snapshots as an additional guide. Our decompositions with GALFIT include bulges, disks, and bars as well as barlenses as a separate component. For 26 of the decomposed galaxies the CALIFA DR2 V500 grating data cubes were used to explore stellar ages and metallicities at the regions of various structure components. Results: We find that 25 ± 2% of the 1064 galaxies in the whole CALIFA sample show either X-shaped or barlens features. In the decomposed galaxies with barlenses, on average 13% ± 2% of the total galaxy light belongs to this component, leaving less than 10% for possible separate bulge components. Most importantly, bars and barlenses are found to have similar cumulative stellar age and metallicity distributions. The metallicities in barlenses are on average near solar, but exhibit a large range. In some of the galaxies barlenses and X-shaped features appear simultaneously, in which case the bar origin of the barlens is unambiguous. Conclusion: This is the first time that a combined morphological and stellar population analysis is used to study barlenses. We show that their stars are accumulated in a prolonged time period concurrently with the evolution of the narrow bar.

Download Full-text

The Evolution of Binary Stars into Contact States

International Astronomical Union Colloquium ◽

10.1017/s0252921100087881 ◽

1989 ◽

Vol 107 ◽

pp. 289-297

Author(s):

R W Hilditch

Keyword(s):

Mass Transfer ◽

Binary Stars ◽

Light Curves ◽

Transfer Rates ◽

Empirical Results ◽

Short Period ◽

Contact Binaries ◽

Low Mass ◽

Evolutionary Paths ◽

First Time

AbstractGood-quality empirical results on 62 short-period binary stars recently summarised by Hilditch & Bell (1987) and Hilditch, King & McFarlane (1988) are discussed in terms of evolutionary paths from detached to semi-detached and contact states. These data suggest two evolutionary paths to the contact binaries - from detached systems directly into contact to form initially shallow-contact systems, and via case A mass transfer to semi-detached states, thence to contact systems. These empirical results support previous arguments based on evolutionary models and less detailed observational data.Concern is expressed about the paucity of high-quality spectroscopic data, particularly for low-mass systems displaying EB-type light curves and the resultant limitations on analyses of those light curves. Such systems provide tests of evolution into contact for the first time, or of broken-contact phases for WUMa-type binaries. The crucial importance of long-term monitoring (decades) of times of minima as indicators of mass transfer rates amongst these interacting binaries is also noted.

Download Full-text

Photometric Evidence of Instability in Eclipsing Systems

Symposium - International Astronomical Union ◽

10.1017/s0074180900018738 ◽

1957 ◽

Vol 3 ◽

pp. 144-158

Author(s):

Frank Bradshaw Wood

Keyword(s):

Eclipsing Binaries ◽

Light Curves ◽

Stable System ◽

Physical Conditions ◽

Short Period

Many eclipsing variables exhibit characteristics that indicate lack of stability. Physically, these systems range from certain short-period dwarfs, which show irregular brightness fluctuations unexplainable by any normal eclipse hypothesis, to systems such as AO Cassiopeiae: class O super-giants whose periods, velocity curves, and light curves have shown remarkable variations. Included are systems having one Wolf-Rayet component and probably one old nova. Many eclipsing binaries show erratic changes of period that are difficult to explain on any concept of a stable system. Indeed, when we consider the physical conditions which must prevail when two stars are located with their surfaces only a few hundred thousand miles from each other, perhaps we should be surprised that the irregularities are not larger.

Download Full-text

The asymmetric light curves of the GSC 2764 1417 (And), GSC 3355 0394 (Per) and GSC 2537 0520 (Psc)

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309992407 ◽

2009 ◽

Vol 5 (S264) ◽

pp. 75-77

Author(s):

Ronald G. Samec ◽

Evan R. Figg ◽

Reid Melton ◽

Christa M. Labadorf ◽

Jess Miller ◽

...

Keyword(s):

Eclipsing Binaries ◽

Light Curves ◽

Close Binaries ◽

Short Period ◽

Solar Type

AbstractSolar-type variability is enhanced in short period close binaries with increased dynamo driven activity. This activity is studied in our analysis of recent light curves taken of the newly discovered eclipsing binaries GSC 2764 1417 (And), GSC 3355 0394 (Per) and GSC 2537 0775 (CVn).

Download Full-text

Light curve analysis of six totally eclipsing W UMa binaries

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psaa109 ◽

2020 ◽

Author(s):

Olivera Latković ◽

Atila Čeki

Keyword(s):

Light Curve ◽

Parameter Space ◽

Curve Analysis ◽

Light Curves ◽

Evolutionary Status ◽

Search Procedure ◽

Light Curve Analysis ◽

Short Period ◽

Mass Ratios ◽

First Time

Abstract We analyze multicolor light curves of six totally eclipsing, short-period W UMa binaries and derive, for the first time, their orbital and stellar parameters. The mass ratios are established robustly through an automated q-search procedure that performs an heuristic survey of the parameter space. Five stars belong to the W and one to the A subtype. The mass ratios range from 0.23 to 0.51 and the fillouts from $10\%$ to $15\%$. We estimate the ages and discuss the evolutionary status of these objects in comparison with a sample of other short-period W UMa binaries from the literature.

Download Full-text

Keck Cosmic Web Imager (KCWI) spectra of globular clusters and ultracompact dwarfs in the halo of M87

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1924 ◽

2020 ◽

Vol 497 (1) ◽

pp. 765-775

Author(s):

Duncan A Forbes ◽

Anna Ferré-Mateu ◽

Mark Durré ◽

Jean P Brodie ◽

Aaron J Romanowsky

Keyword(s):

Globular Clusters ◽

Stellar Population ◽

Velocity Dispersion ◽

Population Analysis ◽

Stellar Populations ◽

Element Abundances ◽

Dispersion Profile ◽

Self Consistent ◽

First Time

ABSTRACT Using the Keck Cosmic Web Imager, we obtain spectra of several globular clusters (GCs), ultracompact dwarfs (UCDs), and the inner halo starlight of M87, at a similar projected galactocentric radius of ∼5 kpc. This enables us, for the first time, to apply the same stellar population analysis to the GCs, UCDs, and starlight consistently to derive ages, metallicities, and alpha-element abundances in M87. We find evidence for a dual stellar population in the M87 halo light, i.e. an ∼80 per cent component by mass that is old and metal-rich and a ∼20 per cent component that is old but metal-poor. Two red GCs share similar stellar populations to the halo light suggesting they may have formed contemporaneously with the dominant halo component. Three UCDs, and one blue GC, have similar stellar populations, with younger mean ages, lower metallicities, and near solar alpha-element abundances. Combined with literature data, our findings are consistent with the scenario that UCDs are the remnant nucleus of a stripped galaxy. We further investigate the discrepancy in the literature for M87’s kinematics at large radii, favouring a declining velocity dispersion profile. This work has highlighted the need for more self-consistent studies of galaxy haloes.

Download Full-text

Light Curves Analysis and Period Study of Two Eclipsing Binaries UZ Lyr and BR Cyg

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/ac3e5f ◽

2021 ◽

Author(s):

Kazem Yoosefi Roobiat ◽

Reza Pazhouhesh

Keyword(s):

Mass Transfer ◽

Radial Velocity ◽

Orbital Period ◽

Binary Systems ◽

Eclipsing Binaries ◽

Light Curves ◽

Secondary Component ◽

Physical Parameters ◽

Time Effects ◽

First Time

Abstract Two eclipsing binary systems UZ Lyr and BR Cyg are the semi-detached types whose secondary component fill its Roche lobe. Although radial velocity and light curves of these systems have already been investigated separately, both radial velocity and light curves of them are analyzed simultaneously for the first time in the present study . Also, the orbital period changes of these systems are studied. Our results show that the mass transfer between components have negligible effects on the orbital period changes of these systems, but two light-time effects are the reasons of the periodic behavior of the O-C curve for UZ Lyr. We could not remark more information about orbital period changes for BR Cyg, but we find a new orbital period for it. By radial velocity and light curves analysis we find a clod spot on the secondary components of BR Cyg. The new geometrical and physical parameters of both systems are obtained and their positions on H-R diagram demonstrated.

Download Full-text

tfaw survey – I. Wavelet-based denoising of K2 light curves. Discovery and validation of two new Earth-sized planets in K2 campaign 1

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2509 ◽

2020 ◽

Vol 498 (2) ◽

pp. 2778-2797

Author(s):

D del Ser ◽

O Fors

Keyword(s):

Detection Efficiency ◽

Light Curves ◽

Type Star ◽

Posterior Distributions ◽

Denoising Method ◽

Low Snr ◽

The One ◽

Almost All ◽

First Time ◽

Better Than

ABSTRACT The wavelet-based detrending and denoising method tfaw is applied for the first time to EVEREST 2.0-corrected light curves to further improve the photometric precision of almost all K2 observing campaigns (C1–C8, C12–C18). The performance of both methods is evaluated in terms of 6 h combined differential photometric precision (CDPP), simulated transit detection efficiency, and planet characterization in different SNR regimes. On average, tfaw median 6 h CDPP is ${\sim} 30{\rm {per \, cent}}$ better than the one achieved by EVEREST 2.0 for all observing campaigns. Using the transit least-squares (tls) algorithm, we show that the transit detection efficiency for simulated Earth–Sun-like systems is ∼8.5× higher for tfaw-corrected light curves than that for EVEREST 2.0 ones. Using the light curves of two confirmed exoplanets, K2-44 b (high SNR) and K2-298 b (low SNR), we show that tfaw yields better Markov chain Monte Carlo posterior distributions, transit parameters compatible with the catalogued ones but with smaller uncertainties, and narrows the credibility intervals. We use the combination of tfaw’s improved photometric precision and tls enhancement of the signal detection efficiency for weak signals to search for new transit candidates in K2 observing campaign 1. We report the discovery of two new K2-C1 Earth-sized planets statistically validated, using the vespa software: EPIC 201170410.02, with a radius of 1.047$^{+0.276}_{-0.257}\mathrm{ R}_{\oplus }$ planet orbiting an M-type star, and EPIC 201757695.02, with a radius of 0.908$^{+0.059}_{-0.064}\mathrm{ R}_{\oplus }$ planet orbiting a K-type star. EPIC 201757695.02 is the 9th smallest planet ever discovered in K2-C1, and the 39th smallest in all K2 campaigns.

Download Full-text