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J/MNRAS/448/464    JHK lightcurves of red giants in the SMC    (Takayama+, 2015)

Using broad-band photometry to examine the nature of long secondary periods in red giants. Takayama M., Wood P.R., Ita Y. <Mon. Not. R. Astron. Soc., 448, 464-483 (2015)> =2015MNRAS.448..464T (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, giant ; Photometry, VRI ; Photometry, infrared ; Effective temperatures ; Spectral types Keywords: circumstellar matter - infrared: stars Abstract: Long-term JHK light curves have recently become available for large numbers of the more luminous stars in the Small Magellanic Cloud (SMC). We have used these JHK light curves, along with OGLE (Optical Gravitational Lensing Experiment) V and I light curves, to examine the variability of a sample of luminous red giants in the SMC which show prominent long secondary periods (LSPs). The origin of the LSPs is currently unknown. In oxygen-rich stars, we found that while most broad-band colours (e.g. V- I) get redder when an oxygen-rich star dims during its LSP cycle, the J-K colour barely changes and sometimes becomes bluer. We interpret the J-K colour changes as being due to increasing water vapour absorption during declining light caused by the development of a layer of dense cool gas above the photosphere. This result and previous observations which indicate the development of a chromosphere between minimum to maximum light suggest that the LSP phenomenon is associated with the ejection of matter from the stellar photosphere near the beginning of light decline. We explore the possibility that broad-band light variations from the optical to the near-infrared regions can be explained by either dust absorption by ejected matter or large spots on a rotating stellar surface. However, neither model is capable of explaining the observed light variations in a variety of colour-magnitude diagrams. We conclude that some other mechanism is responsible for the light variations associated with LSPs in red giants. Description: This is JHK light curves of 7 oxygen rich stars and 14 carbon stars which show the variability of prominent long secondary periods (LSPs). Those stars are cross-identified with OGLE LSP variables in the Small Magellanic Cloud (Soszynski et al. 2011, J/AcA/61/217). A long-term multiband near-IR photometric survey for variable stars in the Large and Small Magellanic Clouds has been carried out at the South African Astronomical Observatory at Sutherland (Ita et al., in preparation). The SIRIUS camera attached to the IRSF 1.4 m telescope was used for this survey and more than 10 yr of observations in the near-IR bands J(1.25 µm), H(1.63 µm) and KS(2.14 µm) band were obtained. In this work, we select the SMC stars from the SIRIUS data base. We obtained the V- and I-band time series of SMC red giants from the OGLE project (Soszynski et al. 2011, J/AcA/61/217). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 90 21 Basic parameters of the program stars at maximum light phot/* 57 123 Individual J, H and K band time-series of stars
See also: II/288 : IRSF Magellanic Clouds Point Source Catalog (Kato+ 2007) J/A+A/401/873 : The SMC in the Far Infrared (Wilke+, 2003) J/AcA/61/217 : VI light curves of SMC long-period variables (Soszynski+, 2011) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 18 A18 --- Name Name (OGLE SMC-LPV-NNNNN in Simbad) 20- 28 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000) 30- 38 F9.5 deg DEdeg Declination in decimal degrees (J2000) 40- 44 F5.2 mag Vmag ? OGLE V-band magnitude 46- 50 F5.2 mag Imag OGLE I-band magnitude 52- 56 F5.2 mag Jmag IRSF J-band magnitude 58- 62 F5.2 mag Hmag IRSF H-band magnitude 64- 68 F5.2 mag Ksmag IRSF KS-band magnitude 70- 73 I4 Lsun L Luminosity derived by applying a bolometric correction to Ks (see Section 4.1) 75- 78 I4 K TBB Blackbody temperature derived from J-KS 80- 83 I4 K Teff Effective temperature derived from J-KS using the formula in Bessell, Wood & Evans (1983MNRAS.202...59B) 85- 88 I4 d PLSP Prominent long secondary period (LSP) 90 A1 --- SpType [OC] Spectral type (Oxygen or Carbon-rich)
Byte-by-byte Description of file: phot/*
Bytes Format Units Label Explanations
1- 14 F14.6 d JD Julian date 16- 21 F6.3 mag mag 2MASS J-, H- or K-band magnitude 23- 28 F6.3 mag Errana Error in deferential image analysis 31- 35 F5.3 mag Errmag Error in reference magnitude 38- 42 F5.3 mag Erroff Error in conversion offset 44- 55 A12 --- Reg Name of the survey region in which the variable star is detected (SMCNNNN-NNNN) 57 A1 --- Subreg [ABCDEFGH] Name of the survey subregion in which the variable star is detected (1)
Note (1): For more details, see Ita et al., in prep.
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 14-Nov-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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