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J/MNRAS/461/839        DIB 661.3nm in Cepheid spectra           (Kashuba+, 2016)

An investigation of the 661.3 nm diffuse interstellar band in Cepheid spectra. Kashuba S.V., Andrievsky S.M., Chekhonadskikh F.A., Luck R.E., Kovtyukh V.V., Korotin S.A., Krelowski J., Galazutdinov G.A. <Mon. Not. R. Astron. Soc., 461, 839-844 (2016)> =2016MNRAS.461..839K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Equivalent widths ; Stars, distances Keywords: stars: variables: Cepheids - ISM: lines and bands - ISM: molecules - ISM: structure Abstract: We have investigated the diffuse interstellar band (DIB) at 661.3nm seen in the spectra of Cepheid stars. After removal of the blending lines of ionized yttrium and neutral iron, we determined the equivalent widths (EWs) of the DIB and used these values to investigate the E(B-V)-DIB EW relation. The relation found from Cepheids matches that found in B stars. This relation can help to find the reddening for newly discovered Cepheids without extensive photometric data, and thus determine their distances. The relation between E(B - V) and the DIB EW does not yield precise reddening values. It is not a substitute for better photometric or spectroscopic methods. At best, it is indicative, but it provides some information that may not be otherwise available. Defining R*=E(B-V)/DIB EW, which we consider to be the analogue of R=E(B-V)/AV, we investigated the Galactic longitudinal dependence of R* assuming that the DIB EW value is representative of the interstellar absorption A$_v$. We found that there is an apparent increase of the R* value that corresponds to the abnormal absorption seen towards Cygnus constellation. Finally, we constructed a 2D map of the DIB EW distribution in the Galactic disc basing on our rather limited sample of 253 spectra of 176 Cepheids. Description: We used spectra of Northern hemisphere Cepheids obtained by REL - one of the co-authors of this paper, with the High Resolution Spectrograph of the Hobby-Eberly Telescope at the McDonald Observatory of the University of Texas at Austin (Texas, USA) with the resolving power of 30000, a typical signal-to-noise ratio of about 100, and wavelength range of 435-780nm. A total of 253 Cepheid spectra were used in the research. We performed an investigation of the 661.356 nm DIB profile in 253 spectra of 176 Cepheids. After removal of the blending YII line the EW of each DIB was calculated for each spectrum. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 85 276 List of the 185 observed stars, their parameters and DIB EWs
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 9 A9 --- Name Star name 11 A1 --- Nsp Spectrum number when more than one for the star 13- 22 A10 "date" Date Observation date 24- 28 F5.3 --- Phase ?=- Phase 30- 33 I4 K Teff Effective temperature 35- 37 F3.1 [m/s2] logg Surface gravity 39- 41 F3.1 km/s vt Microturbulent velocity 43- 47 I5 pc Dist ?=- Distance 49- 54 F6.2 deg GLON Galactic longitude 56- 61 F6.2 deg GLAT Galactic latitude 63- 67 F5.3 mag E(B-V) ?=- B-V colour excess 69- 76 E8.4 nm EW(Y+Fe) Y+Fe equivalent width 78- 85 E8.4 nm EW(DIB) DIB 661.356nm equivalent width
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 27-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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