Eclipsing binaries in local group galaxies: Physical properties of the stars and calibration of the zero-point of the cosmic distance scale

AbstractWe report on the progress of the program to study eclipsing binaries (EBs) in the Local Group galaxies. The primary goals of the program are to determine accurate distances and physical properties of the stars, and to probe the structure and evolution of the host galaxies. In particular, the distance to the Large Magellanic Cloud (LMC) is critically important because this nearby galaxy is used to calibrate most of the important cosmic distance indicators such as Cepheid and RR Lyr variables. Over the last several years, we have demonstrated that the distance of the LMC can be reliably measured using selected eclipsing binaries. The combined analyses of the UV/optical spectrophotometry, radial velocities, and light curves yield the stars’ physical properties (mass, radius, Teff, luminosity, metal abundance) and accurate (2–3%) distances. So far, the physical properties and distances of four LMC EBs have been completed and give a distance to the centroid of the LMC of 48.3 ± 1.6 kpc. Several additional EBs in the LMC and the Small Magellanic Cloud have been observed and are being analyzed. Also several LMC EBs have been observed with FUSE (92 – 119 nm) to further refine values of Teff and interstellar absorption. As an extension of these studies, 19–20th mag EBs in M31 are being observed photometrically and spectroscopically. The results of this extragalactic EB program are discussed along with plans to use EBs to study the host galaxy structure.

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Period–luminosity–metallicity relation of classical Cepheids

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038714 ◽

2020 ◽

Vol 642 ◽

pp. A230

Author(s):

V. Ripepi ◽

G. Catanzaro ◽

R. Molinaro ◽

M. Marconi ◽

G. Clementini ◽

...

Keyword(s):

Near Infrared ◽

Data Gathering ◽

Hubble Constant ◽

Zero Point ◽

Total Sample ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Point Of View ◽

Classical Cepheids ◽

Metal Abundance

Context. Classical Cepheids (DCEPs) are the most important primary indicators for the extragalactic distance scale. Establishing the dependence on metallicity of their period–luminosity and period–Wesenheit (PL and PW) relations has deep consequences for the estimate of the Hubble constant (H0). Aims. We investigate the dependence on metal abundance ([Fe/H]) of the PL and PW relations for Galactic DCEPs. Methods. We combined proprietary and literature photometric and spectroscopic data, gathering a total sample of 413 Galactic DCEPs (372 fundamental mode, DCEP_F, and 41 first-overtone, DCEP_1O) and constructed new metallicity-dependent PL and PW relations in the near-infrared adopting the astrometry-based luminosity. Results. We find indications that the slopes of the PL(KS) and PW(J, KS) relations for Galactic DCEPs might depend on metallicity on the basis of the comparison with the Large Magellanic Cloud relationships. Therefore we used a generalized form of the PL and PW relations to simultaneously take the metallicity dependence of the slope and intercept of these relations into account. Conclusions. We calculated PL and PW relations that for the first time explicitly include a metallicity dependence of the slope and intercept terms. The quality of the available data is insufficient, however, and we cannot yet present conclusive results, but they are relevant from a methodological point of view. The new relations are linked to the geometric measurement of the distance to the Large Magellanic Cloud and allowed us to estimate a Gaia DR2 parallax zero-point offset Δϖ = 0.0615 ± 0.004 mas from the dataset of DCEPs used in this work.

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Period-Age-Metallicity and Period-Age-Color-Metallicity relations for Classical Cepheids: an application to the Gaia EDR3 sample

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2611 ◽

2021 ◽

Author(s):

Giulia De Somma ◽

Marcella Marconi ◽

Santi Cassisi ◽

Vincenzo Ripepi ◽

Adriano Pietrinferni ◽

...

Keyword(s):

Age Distribution ◽

Zero Point ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Helium Abundance ◽

Classical Cepheids ◽

Self Consistent ◽

Data Release ◽

Metal Abundance ◽

The Individual

Abstract Based on updated pulsation models for Classical Cepheids, computed for various assumptions about the metallicity and helium abundance, roughly representative of pulsators in the Small Magellanic Cloud (Z=0.004 and Y=0.25), Large Magellanic Cloud (Z=0.008 and Y=0.25), and M31 (Z=0.03 and Y=0.28), and self-consistent updated evolutionary predictions, we derived Period-Age and multi-band Period-Age-Color relations that also take into account variations in the Mass-Luminosity relation. These results, combined with those previously derived for Galactic Cepheids, were used to investigate the metallicity effect when using these variables as age indicators. In particular, we found that a variation in the metal abundance affects both the slope and the zero point of the above-mentioned relations. The new relations were applied to a sample of Gaia Early Data Release 3 Classical Cepheids. The retrieved distribution of the individual ages confirms that a brighter Mass-Luminosity relation produces older ages and that First Overtone pulsators are found to be concentrated towards older ages with respect to the Fundamental ones at a fixed Mass-Luminosity relation. Moreover, the inclusion of a metallicity term in the Period-Age and Period-Age-Color relations slightly modifies the predicted ages. In particular, the age distribution of the selected sample of Galactic Cepheids is found to be shifted towards slightly older values, when the F-mode canonical relations are considered, with respect to the case at a fixed solar chemical composition. A marginally opposite dependence can be found in the noncanonical F-mode and canonical FO-mode cases.

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Light Curves and Metal Abundances of RR Lyrae Variables in the Bar of the Large Magellanic Cloud

International Astronomical Union Colloquium ◽

10.1017/s0252921100057481 ◽

2000 ◽

Vol 176 ◽

pp. 172-175 ◽

Cited By ~ 1

Author(s):

G. Clementini ◽

A. Bragaglia ◽

L. Di Fabrizio ◽

E. Carretta ◽

R. G. Gratton

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Light Curves ◽

Photometric System ◽

Rr Lyrae Stars ◽

Rr Lyrae ◽

Visual Magnitude ◽

Metal Abundance ◽

Definition Of ◽

Lyrae Stars

AbstractThe Large Magellanic Cloud (LMC) is widely considered a corner-stone of the astronomical distance scale. However, a difference of 0.2−0.3 mag exists in its distance as predicted by the short and long distance scales. Distances to the LMC from Population II objects are founded on the RR Lyrae variables. We have undertaken an observational campaign devoted to the definition of the average apparent luminosity, and to the study of the mass–metallicity relation for RR Lyrae stars in the bar of the LMC. These are compared with analogous quantities for cluster RR Lyrae stars. The purpose is to see whether an intrinsic difference in luminosity, possibly due to a difference in mass, might exist between field and cluster RR Lyrae stars, which could be responsible for the well-known dichotomy between short and long distance scales. Preliminary results are presented on the V and B − V light curves, the average apparent visual magnitude, and the pulsational properties of 102 RR Lyrae stars in the bar of the LMC, observed at ESO in January 1999. The photometric data are accurately tied to the Johnson photometric system. Comparison is presented with the photometry of RR Lyrae stars in the bar of the LMC obtained by the MACHO collaboration (Alcock et al. 1996). Our sample includes 9 double-mode RR Lyrae stars selected from Alcock et al. (1997) for which an estimate of the metal abundance from the ΔS method is presented.

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Fundamental Properties and Distances of Large Magellanic Cloud Eclipsing Binaries. IV. HV 5936

The Astrophysical Journal ◽

10.1086/368309 ◽

2003 ◽

Vol 587 (2) ◽

pp. 685-700 ◽

Cited By ~ 72

Author(s):

E. L. Fitzpatrick ◽

I. Ribas ◽

E. F. Guinan ◽

F. P. Maloney ◽

A. Claret

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Eclipsing Binaries ◽

Fundamental Properties

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Obscured AGN at 1.5 < z < 3.0 from the zCOSMOS-deep Survey

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935062 ◽

2019 ◽

Vol 626 ◽

pp. A9 ◽

Cited By ~ 12

Author(s):

M. Mignoli ◽

A. Feltre ◽

A. Bongiorno ◽

F. Calura ◽

R. Gilli ◽

...

Keyword(s):

Physical Properties ◽

Emission Line ◽

Metal Content ◽

High Redshift ◽

Strong Relationship ◽

Emission Lines ◽

Host Galaxy ◽

Host Galaxies ◽

Uv Emission

Context. The physics and demographics of high-redshift obscured active galactic nuclei (AGN) is still scarcely investigated. New samples of such objects, selected with different techniques, can provide useful insights into their physical properties. Aims. With the goal to determine the properties of the gas in the emitting region of type 2 AGN, in particular, the gas metal content, we exploit predictions from photoionization models, including new parameterizations for the distance of gas distribution from the central source and internal microturbulence in the emitting clouds, to interpret rest-frame UV spectral data. Methods. We selected a sample of 90 obscured (type 2) AGN with 1.45 ≤ z ≤ 3.05 from the zCOSMOS-deep galaxy sample by 5σ detection of the high-ionization C IV λ1549 narrow emission line. This feature in a galaxy spectrum is often associated with nuclear activity, and the selection effectiveness has also been confirmed by diagnostic diagrams based on utraviolet (UV) emission-line ratios. We applied the same selection technique and collected a sample of 102 unobscured (type 1) AGN. Taking advantage of the large amount of multiband data available in the COSMOS field, we investigated the properties of the C IV-selected type 2 AGN, focusing on their host galaxies, X-ray emission, and UV emission lines. Finally, we investigated the physical properties of the ionized gas in the narrow-line region (NLR) of this type 2 AGN sample by combining the analysis of strong UV emission lines with predictions from photoionization models. Results. We find that in order to successfully reproduce the relative intensity of UV emission lines of the selected high-z type 2 AGN, two new ingredients in the photoionization models are fundamental: small inner radii of the NLR (≈90 pc for LAGN = 1045 erg s−1), and the internal dissipative microturbulence of the gas-emitting clouds (with vmicr ≈ 100 km s−1). With these modified models, we compute the gas-phase metallicity of the NLR, and our measurements indicate a statistically significant evolution of the metal content with redshift. Finally, we do not observe a strong relationship between the NLR gas metallicity and the stellar mass of the host galaxy in our C IV-selected type 2 AGN sample.

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Velocity profiles of [CII], [CI], CO, and [OI] and physical conditions in four star-forming regions in the Large Magellanic Cloud

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833398 ◽

2019 ◽

Vol 621 ◽

pp. A62 ◽

Cited By ~ 9

Author(s):

Yoko Okada ◽

Rolf Güsten ◽

Miguel Angel Requena-Torres ◽

Markus Röllig ◽

Jürgen Stutzki ◽

...

Keyword(s):

Physical Properties ◽

High Redshift ◽

Line Emission ◽

Chemical Species ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Continuum Emission ◽

Line Profiles ◽

Star Forming ◽

Star Forming Regions

Aims. The aim of our study is to investigate the physical properties of the star-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. The LMC provides a unique local template to bridge studies in the Galaxy and high redshift galaxies because of its low metallicity and proximity, enabling us to study the detailed physics of the ISM in spatially resolved individual star-forming regions. Following Okada et al. (Okada, Y., Requena-Torres, M. A., Güsten, R., et al. 2015, A&A, 580, A54), we investigate different phases of the ISM traced by carbon-bearing species in four star-forming regions in the LMC, and model the physical properties using the KOSMA-τ PDR model. Methods. We mapped 3–13 arcmin2 areas in 30 Dor, N158, N160, and N159 along the molecular ridge of the LMC in [C II] 158 μm with GREAT on board SOFIA. We also observed the same area with CO(2-1) to (6-5), 13CO(2-1) and (3-2), [C I] 3P1–3P0 and 3P2–3P1 with APEX. For selected positions in N159 and 30 Dor, we observed [O I] 145 μm and [O I] 63 μm with upGREAT. All spectra are velocity resolved. Results. In all four star-forming regions, the line profiles of CO, 13CO, and [C I] emission are similar, being reproduced by a combination of Gaussian profiles defined by CO(3-2), whereas [C II] typically shows wider line profiles or an additional velocity component. At several positions in N159 and 30 Dor, we observed the velocity-resolved [O I] 145 and 63 μm lines for the first time. At some positions, the [O I] line profiles match those of CO, at other positions they are more similar to the [C II] profiles. We interpret the different line profiles of CO, [C II] and [O I] as contributions from spatially separated clouds and/or clouds in different physical phases, which give different line ratios depending on their physical properties. We modeled the emission from the CO, [C I], [C II], and [O I] lines and the far-infrared continuum emission using the latest KOSMA-τ PDR model, which treats the dust-related physics consistently and computes the dust continuum SED together with the line emission of the chemical species. We find that the line and continuum emissions are not well-reproduced by a single clump ensemble. Toward the CO peak at N159 W, we propose a scenario that the CO, [C II], and [O I] 63 μm emission are weaker than expected because of mutual shielding among clumps.

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Photometric study of eclipsing binaries in the Large Magellanic Cloud — I. W UMa type binaries in the Large Magellanic Cloud

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/11/2/005 ◽

2011 ◽

Vol 11 (2) ◽

pp. 175-180 ◽

Cited By ~ 4

Author(s):

Devarapalli Shanti Priya ◽

Kandulapati Sriram ◽

Pasagada Vivekananda Rao

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Eclipsing Binaries ◽

Photometric Study

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The MACHO Project Large Magellanic Cloud Variable Star Inventory. XII. Three Cepheid Variables in Eclipsing Binaries

The Astrophysical Journal ◽

10.1086/340560 ◽

2002 ◽

Vol 573 (1) ◽

pp. 338-350 ◽

Cited By ~ 26

Author(s):

C. Alcock ◽

R. A. Allsman ◽

D. R. Alves ◽

A. C. Becker ◽

D. P. Bennett ◽

...

Keyword(s):

Variable Star ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Eclipsing Binaries ◽

Cepheid Variables

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Eclipsing Binaries in the Magellanic Clouds

Highlights of Astronomy ◽

10.1017/s153929960001618x ◽

2005 ◽

Vol 13 ◽

pp. 451-451

Author(s):

Andrzej Udalski

Keyword(s):

Gravitational Lensing ◽

Direct Determination ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Eclipsing Binaries ◽

Physical Parameters ◽

Second Phase ◽

Internet Archive ◽

Pulsating Stars ◽

Eclipsing Stars

We present results of a search for eclipsing binaries in the Magellanic Cloud fields covering central parts of these galaxies. The data were collected during the second phase of the Optical Gravitational Lensing Experiment survey (OGLE-II) in 1997-2000. In total, about 1500 and 3000 eclipsing stars were found in the Small and Large Magellanic Cloud, respectively (Udalski et al. 1998, Wyrzykowski et al. 2003). The photometric data of all objects are available to the astronomical community from the OGLE Internet archive (http://sirius.astrouw.edu.pl/~ogle/). OGLE-II data contain a full variety of classical eclipsing objects of all types: Algol EA-type, β-Lyr EB-type and W UMA EW-type stars. Large samples of stars allow to study in detail statistical properties of eclipsing objects. OGLE data also contain many very unusual eclipsing stars. Examples include eclipsing variable B-type stars (Mennickent et al. 2003), many spotted stars or eclipsing stars with a Cepheid as a component (Udalski et al. 1999). Recently three objects from the LMC revealing simultaneously RR Lyr and eclipsing binary type variability were discovered (Soszyński et al 2003). If the follow-up observations confirm that both components are physically bound and not optical blends these stars will provide a unique opportunity of direct determination of physical parameters of RR Lyr pulsating stars.

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