J/A+A/576/A30 NIR light-curve templates for classical Cepheids (Inno+, 2015)
New NIR light-curve templates for classical Cepheids.
Inno L., Matsunaga N., Romaniello M., Bono G., Monson A., Ferraro I.,
Iannicola G., Persson E., Buonanno R., Freedman W., Gieren W.,
Groenewegen M.A.T., Ita Y., Laney C.D., Lemasle B., Madore B.F.,
Nagayama T., Nakada Y., Nonino M., Pietrzynski G., Primas F., Scowcroft V.,
Soszynski I., Tanabe T., Udalski A.
<Astron. Astrophys., 576, A30-30 (2015)>
=2015A&A...576A..30I 2015A&A...576A..30I
ADC_Keywords: Stars, variable; Photometry, infrared
Keywords: stars: variables: Cepheids - stars: distances - stars: oscillations
Abstract:
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. 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). 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 0.015mag
(J band) to 0.019mag (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. 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.
Description:
Our analysis is based on the largest available sample of
fundamental-mode Cepheids with well-covered light-curves in the NIR
and in optical (V, I) bands. This sample covers a very broad period
range (1-100 days). We collected J, H, and KS band observations from
four different data sets: Laney & Stobie (1992A&AS...93...93L 1992A&AS...93...93L, 51) and
Monson & Pierce (2011ApJS..193...12M 2011ApJS..193...12M, 131) for Galactic Cepheids,
Persson et al. (2004AJ....128.2239P 2004AJ....128.2239P, 92) for LMC Cepheids, and the
IRSF survey catalog for ∼500 Small Magellanic Cloud (SMC) Cepheids.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 103 275 Pulsation parameters for FU calibrating Cepheids
table3.dat 99 10 Pulsation parameters for FO calibrating Cepheids
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See also:
J/AJ/128/2239 : JHKs photometry of 92 LMC Cepheids (Persson+, 2004)
J/ApJS/193/12 : JHK photometry of Northern Galactic Cepheids (Monson+, 2011)
J/AcA/58/163 : VI light curves of LMC classical Cepheids (Soszynski+, 2008)
J/AcA/60/17 : VI light curves of SMC classical Cepheids (Soszynski+, 2010)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Gal Galaxy (MW, LMC or SMC)
5- 13 A9 --- ID Primary identification
15- 19 A5 --- --- [OGLE-]
20- 31 A12 --- OID OGLE identification for LMC and SMC Cepheids
(LMC-CEP-NNNN or SMC-CEP-NNNN)
33- 39 F7.5 [d] logP [0.15/1.84] log(Period)
41- 46 F6.3 mag <Vmag> Average V magnitude
48- 53 F6.3 mag <Jmag> ?=- Average J magnitude
55- 60 F6.3 mag <Hmag> ?=- Average H magnitude
62- 67 F6.3 mag <Ksmag> ?=- Average Ks magnitude
69- 72 F4.2 mag Vamp Amplitude of pulsation in V band
74- 77 F4.2 mag Jamp ?=- Amplitude of pulsation in J band
79- 82 F4.2 mag Hamp ?=- Amplitude of pulsation in H band
84- 87 F4.2 mag Kamp ?=- Amplitude of pulsation in Ks band
89- 99 F11.3 d JD0 Zero-point, defined as the epoch of the mean
magnitude along the rising branch
101-103 A3 --- Sam Sample designation (1)
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Note (1): Sample as follows:
LS = Laney and Stobie, 1992A&AS...93...93L 1992A&AS...93...93L
MP = Monson and Pierce, 2011ApJS..193...12M 2011ApJS..193...12M, Cat. J/ApJS/193/12
P04 = Persson et al., 2004AJ....128.2239P 2004AJ....128.2239P, Cat. J/AJ/128/2239
SMC = IRSF/OGLE sample
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 27-May-2015