The OGLE Collection of Variable Stars. Nearly 66,000 Mira stars in the Milky Way
Patryk Iwanek, Igor Soszyński, Szymon Kozłowski, Radosław Poleski, Paweł Pietrukowicz, Jan Skowron, Marcin Wrona, Przemysław Mróz, Andrzej Udalski, Michał K. Sz… 展开作者
Patryk Iwanek, Igor Soszyński, Szymon Kozłowski, Radosław Poleski, Paweł Pietrukowicz, Jan Skowron, Marcin Wrona, Przemysław Mróz, Andrzej Udalski, Michał K. Szymański, Dorota M. Skowron, Krzysztof Ulaczyk, Mariusz Gromadzki, Krzysztof Rybicki, Milena Ratajczak
We present a collection of 65,981 Mira-type variable stars found in the Optical Gravitational Lensing Experiment (OGLE) project database. Two-thirds of our sample (40,356 objects) are located in the Galactic bulge fields, whereas 25,625 stars are in the Galactic disk. The vast majority of the collection (47,532 objects) are new discoveries. We provide basic observational parameters of the Mira variables: equatorial coordinates, pulsation periods, $I$-band and $V$-band mean magnitudes, $I$-band brightness amplitudes, and identifications in other catalogs of variable stars. We also provide the $I$-band and $V$-band time-series photometry collected since 1997 during the OGLE-II, OGLE-III, and OGLE-IV phases. The classical selection process, i.e., mostly based on the visual inspection of light curves by experienced astronomers, led us to the high purity of the catalog. As a result, this collection can be used as a training set in the machine learning classification algorithms. Using overlapping parts of adjacent OGLE fields, we estimate the completeness of the catalog to be about 96%. We compare and discuss the statistical features of Miras located in different regions of the Milky Way. We show examples of stars that change their type over time, from a semi-regular variable to Mira and vice versa. This dataset is perfectly suited to study the three-dimensional structure of the Milky Way, and it may help to explain the puzzle of the X-shaped bulge.
We investigate infrared properties of OGLE4 Mira variables in our Galaxy. For each object, we cross-identify the AllWISE, 2MASS, Gaia, and IRAS counterparts. We present various IR two-color diagrams (2CDs) and period-magnitude and period-color relations for the Mira variables. Generally, the Mira variables with longer periods are brighter in the IR fluxes and redder in the IR colors. In this work, we also revise and update the previous catalog of AGB stars in our Galaxy using the new sample of OGLE4 Mira variables. Now, we present a new catalog of 74,093 (64,609 O-rich and 9484 C-rich) AGB sta…
New Mira Variables from the MACHO Galactic Bulge Fields, part II
我们提出了一个新的样本525米拉变量的方向的银河系隆起，扩大以前的样本69和500个对象，分别，从而结束我们的搜索新的米拉变量在银河系隆起领域。本样本中的364颗Mira是首次报道的变星。我们将我们的样本与银河系隆起中OGLE-III长周期变星目录（LPV）中的Mira星样本进行了交叉相关，发现了146个匹配项; OGLE和OGLE的周期总体上非常一致。我们目前的样本的所有恒星的摘要数据，并给出一个统计概述，比较的性质的CASTO和OGLE样本和扩大我们以前的论文中的分析。光变曲线、折叠光变曲线和更多细节可通过AAVSO国际变星索引（http：//www.aavso.org/vsx/）获得。我们的论文（Bernhard，2011; Huemmerich and Bernhard，2012和本论文）中提供的来自1990年银河隆起场的Mira变星的完整样本数据可以在附录中找到。
Long-period variable stars (LPVs) are pulsating red giants, primarily in the asymptotic giant branch phase, and they include both Miras and semi-regular variables (SRVs). Their period-age and period-luminosity relations enable us to trace different stellar populations, as they are intrinsically very bright and cover a wide range in distances and ages. The purpose of this study is to establish a census of LPV stars in a region close to the Galactic center, using the six-year database of the Vista Variables in the Vía Láctea (VVV) ESO Public Survey, as well as to describe the methodology that wa…
We present the largest collection of delta Scuti-type stars in the Milky Way. Together with the recently published OGLE collection of delta Sct variables in the inner Galactic bulge, our sample consists of 24 488 objects distributed along the Milky Way plane, over galactic longitudes ranging from about -170 deg to +60 deg. The collection data include the I- and V-band time-series photometry collected since 1997 during the OGLE-II, OGLE-III, and OGLE-IV surveys. We show the on-sky distribution of delta Sct stars in the Galactic bulge and disk, discuss their period, luminosity and amplitude dist…
We study the three-dimensional structure of the Milky Way using 65,981 Mira variable stars discovered by the Optical Gravitational Lensing Experiment (OGLE) survey. The spatial distribution of the Mira stars is analyzed with a model containing three barred components that include the X-shaped boxy component in the Galactic center (GC), and an axisymmetric disk. We take into account the distance uncertainties by implementing the Bayesian hierarchical inference method. The distance to the GC is $R_0 = 7.66 \pm 0.01 \mathrm{(stat.)} \pm 0.39 \mathrm{(sys.)}$ kpc, while the inclination of the majo…
We comprehensively study the variability of Miras in the Large Magellanic Cloud (LMC) by simultaneous analysing light curves in 14 bands in the range of 0.5$-$24 microns. We model over 20-years-long, high cadence $I$-band light curves collected by The Optical Gravitational Lensing Experiment (OGLE) and fit them to light curves collected in the remaining optical/near-infrared/mid-infrared bands to derive both the variability amplitude ratio and phase-lag as a function of wavelength. We show that the variability amplitude ratio declines with the increasing wavelength for both oxygen-rich (O-rich…
The properties of the Milky Way's nuclear stellar disc give crucial information on the epoch of bar formation. Mira variables are promising bright candidates to study the nuclear stellar disc, and through their period-age relation dissect its star formation history. We report on a sample of $1782$ Mira variable candidates across the central $3\times3\,\mathrm{deg}^2$ of the Galaxy using the multi-epoch infrared VISTA Variables in Via Lactea (VVV) survey. We describe the algorithms employed to select candidate variable stars and then model their light curves using periodogram and Gaussian proce…
We analyzed the light curves of 165 AGB variables, mostly Miras, in the sky area centered between M16 and M17 (l=16, b=0), using the OGLE GVS database in the I_C band. Comparison with the published light curves, derived about 50 years earlier by P.~Maffei using Kodak I-N photographic plates, allowed us to find no significant period changes in any star. Remarkably, a few stars of the sample appear to have substantially changed their average luminosity, the most striking case being KZ Ser. We provide a better identification for three stars: IX Ser, NSV 10522, and NSV 10326, all of them being Mir…
We present an analysis of high latitude $δ$ Scuti stars ($\left|b\right|> 1^{\circ}$) in the Galactic bulge region ($-8^{\circ}.3< l<9^{\circ}.4$) using a clean sample of the photometric data of $7,440$ stars recently released by the OGLE-IV project. The geometrical parameters of the bulge are determined based on Maximum Likelihood (ML) analysis in five-dimensional parameter space. More refined values of these parameters as well as their uncertainties are obtained from a fully Bayesian Markov Chain Monte Carlo (MCMC) analysis. Approximating the bulge as an ellipsoid, the distribution of the nu…
The number and properties of observed gravitational microlensing events depend on the distribution and kinematics of stars and other compact objects along the line of sight. In particular, precise measurements of the microlensing optical depth and event rate toward the Galactic bulge enable strict tests of competing models of the Milky Way. Previous estimates, based on samples of up to a few hundred events, gave larger values than expected from the Galactic models and were difficult to reconcile with other constraints on the Galactic structure. Here we used long-term photometric observations o…
We present Period-Luminosity and Period-Luminosity-Color relations at maximum-light for Mira variables in the Magellanic Clouds using time-series data from the Optical Gravitational Lensing Experiment (OGLE-III) and {\it Gaia} data release 2. The maximum-light relations exhibit a scatter typically up to $\sim 30\%$ smaller than their mean-light counterparts. The apparent magnitudes of Oxygen-rich Miras at maximum-light display significantly smaller cycle-to-cycle variations than at minimum-light. High-precision photometric data for Kepler Mira candidates also exhibit stable magnitude variation…
Many open clusters listed in modern catalogues were initially reported by visual astronomers as apparent overdensities of bright stars. As observational techniques and analysis methods continue to improve, some of them have been shown to be chance alignments of stars and not true clusters. Recent publications have provided membership lists for over a thousand clusters, however, many nearby objects listed in the literature have so far evaded detection. We aim to update the Gaia DR2 cluster census by performing membership determinations for known clusters that had been missed by previous studies…
Semi-regular variables (SRVs) are similar to Miras in brightness, and they also follow PLRs, though not necessarily the same as Miras. As potential standard candles they are more challenging than Miras due to their smaller variability amplitudes and less regular light curves, but they are substantially more numerous and especially promising to probe old stellar populations. We aim to characterize the variability of SRVs, with focus on their connection with Miras, in order to prepare the ground for investigating their potential as distance indicators. We examine SRVs and Miras in the Magellanic…
We present an upgrade of the OGLE Collection of RR Lyrae stars in the Galactic bulge and disk. The size of our sample has been doubled and reached 78 350 RR Lyr variables, of which 56 508 are fundamental-mode pulsators (RRab stars), 21 321 pulsate solely in the first-overtone (RRc stars), 458 are classical double-mode pulsators (RRd stars), and 63 are anomalous RRd variables (including five triple-mode pulsators). For all the newly identified RR Lyr stars, we publish time-series photometry obtained during the OGLE Galaxy Variability Survey. We present the spatial distribution of RR Lyr stars o…
We present a collection of 10 111 genuine delta Sct-type pulsating variable stars detected in the OGLE-IV Galactic bulge fields. In this sample, 9835 variables are new discoveries. For most of the stars photometric data cover the whole decade 2010-2019. We illustrate a huge variety of light curve shapes of delta Sct variables. Long-term observations have allowed us to spot objects with evident period, amplitude, and mean brightness variations. Our analysis indicates that about 28% of the stars are single-mode pulsators. Fourteen delta Sct stars show additional eclipsing or ellipsoidal binary m…
We share the most up-to-date, carefully verified list of classical Cepheids residing in the Galaxy. Based on long-term OGLE experience in the field of variable stars, we have inspected candidates for Cepheids from surveys such as ASAS, ASAS-SN, ATLAS, Gaia, NSVS, VVV, WISE, ZTF, among others, and also known sources from the General Catalogue of Variable Stars. Only objects confirmed in the optical range as classical Cepheids are included in the list. We provide Gaia EDR3 identifications of the stars. Purity of the sample exceeds 97 per cent, while its completeness is of about 88 per cent down …
Mapping the Inner Milky Way with Infrared-Derived Distances to AGB Stars
University of New Mexico（新墨西哥大学）；Inter-University Centre for Astronomy and Astrophysics (IUCAA)（大学间天文学与天体物理学中心）；National Radio Astronomy Observatory（国家射电天文台）
Anomalous Cepheids (ACs) are metal-deficient, core-helium-burning pulsating stars with masses in the range 1.2-2.2 M_S. Until recently, all known ACs were pure single-mode pulsators. The first candidate for an AC pulsating in more than one radial mode - OGLE-GAL-ACEP-091 - was recently identified in the Milky Way based on the photometric database of the Optical Gravitational Lensing Experiment (OGLE) survey. We analyze this object showing that it is actually a triple-mode pulsator. Its position in the Petersen diagram, the light-curve morphology quantified by Fourier coefficients, and absolute…
We report on the results of a comprehensive search for Cepheid variable stars in the fields photometricallymonitored by the OGLE Galaxy Variability Survey. We identify 742 Cepheids not included in the first release of the OGLE Collection of Galactic Cepheids and reclassify several dozen previously published variables. The upgraded collection comprises 1974 classical, 1625 type II, and 119 anomalous Cepheids located in the area of about 3000 square degrees covering the disk and bulge of the Milky Way. We present the most interesting objects in our sample: an isolated group of long-period double…
We present an updated three dimensional map of the Milky Way based on a sample of 2431 classical Cepheid variable stars, supplemented with about 200 newly detected classical Cepheids from the OGLE survey. The new objects were discovered as a result of a dedicated observing campaign of the ~280 square degree extension of the OGLE footprint of the Galactic disk during 2018-2019 observing seasons. These regions cover the main part of the northern Galactic warp that has been deficient in Cepheids so far. We use direct distances to the sample of over 2390 classical Cepheids to model the distributio…
Light curve spectral energy distribution fitting of 13 carbon-rich Mira variables stars in the Small Magellanic Cloud
National and Kapodistrian University of Athens（雅典国立卡波迪斯特里安大学）；Università di Padova（帕多瓦大学）；INAF-Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；University of Geneva（日内瓦大学）；Koninklijke Sterrenwacht van België（比利时皇家天文台）；SISSA（的里雅斯特国际高等研究学院）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）
The Cepheid variables in SMC, LMC, the Milky Way, M33 and M31 are used to examine the dependence of pulsation mode on metallicity which was previously found in red supergiants. The initial samples of Cepheids are collected from the Cepheid catalogs identified from the OGLE, PS1, DIRECT, WISE and ZTF surveys. The contaminants are removed with the help of the Gaia/EDR3 astrometric information for extra galaxies or by comparing the geometric distance and the distance from the P-L relation for the Milky Way. The division of fundamental and first-overtone mode is refined according to the gap betwee…
In order to characterize 22 new globular cluster (GC) candidates in the Galactic bulge, we present their colour-magnitude diagrams (CMDs) and Ks-band luminosity functions (LFs) using the near-infrared VVV database as well as Gaia-DR2 proper motion dataset. CMDs were obtained, on one hand, after properly decontaminating the observed diagrams from background/foreground disc stars and other sources. On the other hand, CMDs were also obtained based upon star selection in proper motion diagrams. Taking into account our deep CMDs and LFs analyses, we find that 17 out of 22 new GC candidates may be r…
The advancement in the field of data science especially in machine learning along with vast databases of variable star projects like the Optical Gravitational Lensing Experiment (OGLE) encourages researchers to analyse as well as classify light curves of different variable stars automatically with efficiency. In the present work, we have demonstrated the relative performances of principal component analysis (PCA) and independent component analysis (ICA) applying to huge databases of OGLE variable star light curves after obtaining 1000 magnitudes between phase 0 to 1 with step length 0.001 for …
