Physical parameters and the projection factor of the classical Cepheid in the binary system OGLE-LMC-CEP-0227

Pilecki, B.; Graczyk, D.; Pietrzyński, G.; Gieren, W.; Thompson, I. B.; Freedman, Wendy L.; Scowcroft, Victoria; Madore, Barry F.; Udalski, A.; Soszyński, I.; Konorski, P.; Smolec, R.; Nardetto, N.; Bono, G.; Moroni, P. G. Prada; Storm, J.; Gallenne, A.

doi:10.1093/mnras/stt1529

Cited by 73 publications

(83 citation statements)

References 44 publications

(51 reference statements)

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“…The uncertainty of p was computed from the combination of the error bars of the independent measurements of OGLE-LMC-CEP-0227 (P = 3.80 d, p = 1.21 ± 0.05, Pilecki et al 2013), δ Cep (P = 5.37 d, p = 1.288 ± 0.054, Mérand et al 2015), and the present measurement of RS Pup (P = 41.5 d, p = 1.250 ± 0.064). We did not average the error bars of the different p-factor measurements from the HST/FGS distances as the degree of correlation between them and the possible associated systematics are uncer- Pilecki et al (2013) and Gieren et al (2015), and we selected only the best p-factor of δ Cep derived by Mérand et al (2015). In agreement with the present results, Breitfelder et al (2016) also concluded from a fit to the complete sample of measured p-factors that a constant value of p = 1.324 ± 0.024 (1σ from our value) reproduces the measurements.…”

Section: Discussionmentioning

confidence: 99%

“…Even for distant Cepheids, however, whose angular diameters cannot be measured directly, the robustness of the SPIPS algorithm will enable an accurate calibration of their physical properties, including the p-factor, once their parallaxes are known. (Benedict et al 2002(Benedict et al , 2007, the orange points are the LMC eclipsing Cepheids (Pilecki et al 2013;Gieren et al 2015). The solid line and orange shaded area represent the weighted average p = 1.293 ± 0.039.…”

Section: Discussionmentioning

confidence: 99%

“…Recent observational efforts have produced accurate measurements of the p-factor of Cepheids (Mérand et al 2005b;Pilecki et al 2013;Breitfelder et al 2015;Gieren et al 2015;Breitfelder et al 2016), with the objective to reduce this source of systematic uncertainty. However, these p-factor calibrations up to now were essentially obtained on low-luminosity, relatively short-period Cepheids (P 10 days) that are the most common in the Galaxy.…”

Section: Introductionmentioning

confidence: 99%

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Observational calibration of the projection factor of Cepheids

Kervella

Trahin

Bond

et al. 2017

A&A

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The projection factor (p-factor) is an essential component of the classical Baade-Wesselink (BW) technique, which is commonly used to determine the distances to pulsating stars. It is a multiplicative parameter used to convert radial velocities into pulsational velocities. As the BW distances are linearly proportional to the p-factor, its accurate calibration for Cepheids is of critical importance for the reliability of their distance scale. We focus on the observational determination of the p-factor of the long-period Cepheid RS Pup (P = 41.5 days). This star is particularly important as this is one of the brightest Cepheids in the Galaxy and an analog of the Cepheids used to determine extragalactic distances. An accurate distance of 1910 ± 80 pc (±4.2%) has recently been determined for RS Pup using the light echoes propagating in its circumstellar nebula. We combine this distance with new VLTI/PIONIER interferometric angular diameters, photometry, and radial velocities to derive the p-factor of RS Pup using the code Spectro-Photo-Interferometry of Pulsating Stars (SPIPS). We obtain p = 1.250 ± 0.064 (±5.1%), defined for cross-correlation radial velocities. Together with measurements from the literature, the p-factor of RS Pup confirms the good agreement of a constant p = 1.293 ± 0.039 (±3.0%) model with the observations. We conclude that the p-factor of Cepheids is constant or mildly variable over a broad range of periods (3.7 to 41.5 days).

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observational calibration of the projection factor of Cepheids

Kervella

Trahin

Bond

et al. 2017

A&A

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“…We used RaveSpan (Pilecki et al 2012(Pilecki et al , 2013 to measure the radial velocities of both stars in the system using the broadening function (BF) formalism (Rucinski 1992(Rucinski , 1999. We used templates from the library of synthetic LTE spectra by Coelho et al (2005) matching the mean values of estimated effective temperature and gravity of the stars in the binary.…”

Section: Radial Velocitiesmentioning

confidence: 99%

A solar twin in the eclipsing binary LL Aquarii

Graczyk

Smolec

Pavlovski

et al. 2016

A&A

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Aims. In the course of a project to study eclipsing binary stars in vinicity of the Sun, we found that the cooler component of LL Aqr is a solar twin candidate. This is the first known star with properties of a solar twin existing in a non-interacting eclipsing binary, offering an excellent opportunity to fully characterise its physical properties with very high precision. Methods. We used extensive multi-band, archival photometry and the Super-WASP project and high-resolution spectroscopy obtained from the HARPS and CORALIE spectrographs. The spectra of both components were decomposed and a detailed LTE abundance analysis was performed. The light and radial velocity curves were simultanously analysed with the Wilson-Devinney code. The resulting highly precise stellar parameters were used for a detailed comparison with PARSEC, MESA, and garstec stellar evolution models.Results. LL Aqr consists of two main-sequence stars (F9 V + G3 V) with masses of M 1 = 1.1949 ± 0.0007 and M 2 = 1.0337 ± 0.0007 M , radii R 1 = 1.321±0.006 and R 2 = 1.002±0.005 R , temperatures T 1 = 6080±45 and T 2 = 5703±50 K and solar chemical composition [M/H] = 0.02 ± 0.05. The absolute dimensions, radiative and photometric properties, and atmospheric abundances of the secondary are all fully consistent with being a solar twin. Both stars are cooler by about 3.5σ or less metal abundant by 5σ than predicted by standard sets of stellar evolution models. When advanced modelling was performed, we found that full agreement with observations can only be obtained for values of the mixing length and envelope overshooting parameters that are hard to accept. The most reasonable and physically justified model fits found with MESA and garstec codes still have discrepancies with observations but only at the level of 1σ. The system is significantly younger that the Sun, with an age between 2.3 Gyr and 2.7 Gyr, which agrees well with the relatively high lithium abundance of the secondary, A(Li) = 1.65 ± 0.10 dex.

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“…The 'non-spotted' sample contains 14 LMC and SMC systems (Graczyk et al 2012;Pietrzyński et al 2013;Pilecki et al 2013;Graczyk et al 2014), KIC 8410673 (Frandsen et al 2013), AI Phe (Andersen et al 1988;He lminiak et al 2009), TZ For (Andersen et al 1991), OW Gem (Ga lan et al 2008), α Aur (Torres et al 2009(Torres et al , 2015, CF Tau (Lacy et al 2012), V432 Aur (Siviero et al 2004), HD187669 (He lminiak et al 2015), ASAS J180057-2333.8, (Suchomska et al 2015), ASAS J182510-2435.5 (Ratajczak et al 2013), and two more systems we have analysed but not published yet (ASAS-061, V64). We want to note, that the 'non-spotted' systems may also be active, but the activity level must be lower than for the 'spotted' ones, as there is no clear sign of variability in the published photometry, usually more precise than the ASAS data.…”

Section: Giants With and Without Spots In Eclipsing Binariesmentioning

confidence: 99%

Orbital and physical parameters of eclipsing binaries from the ASAS catalogue – IX. Spotted pairs with red giants

Ratajczak

Hełminiak

Konacki

et al. 2016

Mon. Not. R. Astron. Soc.

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We present spectroscopic and photometric solutions for three spotted systems with red giant components. Absolute physical and orbital parameters for these double-lined detached eclipsing binary stars are presented for the first time. These were derived from the V -, and I -band ASAS and WASP photometry, and new radial velocities calculated from high quality optical spectra we obtained with a wide range of spectrographs and using the two-dimensional cross-correlation technique (TODCOR). All of the investigated systems (ASAS J184949-1518.7, BQ Aqr, and V1207 Cen) show the differential evolutionary phase of their components consisting of a main sequence star or a subgiant and a red giant, and thus constitute very informative objects in terms of testing stellar evolution models. Additionally, the systems show significant chromospheric activity of both components. They can be also classified as classical RS CVn-type stars. Besides the standard analysis of radial velocities and photometry, we applied spectral disentangling to obtain separate spectra for both components of each analysed system which allowed for a more detailed spectroscopic study. We also compared the properties of red giant stars in binaries that show spots, with those that do not, and found that the activity phenomenon is substantially suppressed for stars with Rossby number higher than ∼1 and radii larger than ∼20 R ⊙ .

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Physical parameters and the projection factor of the classical Cepheid in the binary system OGLE-LMC-CEP-0227

Cited by 73 publications

References 44 publications

Observational calibration of the projection factor of Cepheids

Observational calibration of the projection factor of Cepheids

A solar twin in the eclipsing binary LL Aquarii

Orbital and physical parameters of eclipsing binaries from the ASAS catalogue – IX. Spotted pairs with red giants

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