Home > Science Articles > Peer Reviewed Articles > New NIR light-curve templates for classical Cepheids > MARC |

000002114 001__ 2114 000002114 005__ 20160706150439.0 000002114 0247_ $$2DOI$$a10.1051/0004-6361/201424396 000002114 037__ $$aASTROimport-271 000002114 100__ $$aInno, L. 000002114 245__ $$aNew NIR light-curve templates for classical Cepheids 000002114 260__ $$c2015 000002114 520__ $$aAims: We present new near-infrared (NIR) light-curve templates for fundamental (FU, J, H, KS) and first overtone (FO, J) classical Cepheids. The new templates together with period-luminosity and period-Wesenheit (PW) relations provide Cepheid distances from single-epoch observations with a precision only limited by the intrinsic accuracy of the method adopted. Methods: The templates rely on a very large set of Galactic and Magellanic Cloud Cepheids (FU, ~600; FO, ~200) with well-sampled NIR (IRSF data set) and optical (V, I; OGLE data set) light-curves. To properly trace the change in the shape of the light-curve as a function of pulsation period, we split the sample of calibrating Cepheids into ten different period bins. The templates for the first time cover FO Cepheids and the short-period range of FU Cepheids (P = 5 days). Moreover, the phase zero-point is anchored to the phase of the mean magnitude along the rising branch. The new approach has several advantages in sampling the light-curve of bump Cepheids when compared with the canonical phase of maximum light. We also provide new empirical estimates of the NIR-to-optical amplitude ratios for FU and FO Cepheids. We perform detailed analytical fits using seventh-order Fourier series and multi-Gaussian periodic functions. The latter are characterized by fewer free parameters (nine vs. fifteen). Results: The mean NIR magnitudes based on the new templates are up to 80% more accurate than single-epoch NIR measurements and up to 50% more accurate than the mean magnitudes based on previous NIR templates, with typical associated uncertainties ranging from 0.015 mag (J band) to 0.019 mag (KS band). Moreover, we find that errors on individual distance estimates for Small Magellanic Cloud Cepheids derived from NIR PW relations are essentially reduced to the intrinsic scatter of the adopted relations. Conclusions: Thus, the new templates are the ultimate tool for estimating precise Cepheid distances from NIR single-epoch observations, which can be safely adopted for future interesting applications, including deriving the 3D structure of the Magellanic Clouds. Full Tables 2 and 4 are available in electronic form at http://www.aanda.org 000002114 700__ $$aMatsunaga, N. 000002114 700__ $$aRomaniello, M. 000002114 700__ $$aBono, G. 000002114 700__ $$aMonson, A. 000002114 700__ $$aFerraro, I. 000002114 700__ $$aIannicola, G. 000002114 700__ $$aPersson, E. 000002114 700__ $$aBuonanno, R. 000002114 700__ $$aFreedman, W. 000002114 700__ $$aGieren, W. 000002114 700__ $$aGroenewegen, M. A. T. 000002114 700__ $$aIta, Y. 000002114 700__ $$aLaney, C. D. 000002114 700__ $$aLemasle, B. 000002114 700__ $$aMadore, B. F. 000002114 700__ $$aNagayama, T. 000002114 700__ $$aNakada, Y. 000002114 700__ $$aNonino, M. 000002114 700__ $$aPietrzynski, G. 000002114 700__ $$aPrimas, F. 000002114 700__ $$aScowcroft, V. 000002114 700__ $$aSoszynski, I. 000002114 700__ $$aTanabé, T. 000002114 700__ $$aUdalski, A. 000002114 773__ $$cA30$$pAstronomy and Astrophysics$$v576$$y2015 000002114 85642 $$ahttp://esoads.eso.org/abs/2015A%26A...576A..30I 000002114 905__ $$apublished in 000002114 980__ $$aREFERD