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J/A+A/410/905  Interstellar reddening parameter measurements (Patriarchi+, 2003)

A study of RV in galactic O stars from the 2MASS catalogue. Patriarchi P., Morbidelli L., Perinotto M. <Astron. Astrophys. 410, 905 (2003)> =2003A&A...410..905P
ADC_Keywords: Stars, O ; Photometry, infrared ; Interstellar medium ; Reddening Keywords: ISM: dust, extinction Abstract: We present new measurements of the interstellar reddening parameter RV=AV/E(B-V) towards 185 O stars, using J, H, Ks photometry from the 2MASS project. The average RV from these is of 3.19±0.50. All objects whose RV departs from this value by more than 2 sigma have been recognized. Ten objects have RV higher than this value and two lower. In the Cygnus region RV values follow the behaviour of the general interstellar medium, while in the Carina arm, in spite of the relatively larger distance, local cloud effects prevail. The relatively few stars of our sample whose Hipparcos parallaxes are reliable, are found to have distances systematically smaller than the distances derived by the spectroscopic parallaxes. We argue that this effect is consistent with the recently claimed discovery of grey extinction towards OB stars. Description: The photometric data of the J, H, Ks filters of the 185 stars are reported in Table 1 together with their photometric errors, as given in the 2MASS catalogues. The quantity AV was then determined from the J, H, Ks and V photometry using the method developed by Cardelli et al. (1989ApJ...345..245C), who assumed that the shape of the IR extinction law is invariant. We report in Table 2 the full set of relevant quantities. From AV in Table 2 and V in Table 1 we have derived the distances making use of the calibration Mv vs. spectral type from Panagia (1973AJ.....78..929P). The lines of sight with "anomalous" RV are marked in Table 2 with "s" and "l" for small and large RV, respectively. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 65 185 J, H, Ks photometry of O stars from 2MASS table2.dat 74 185 Extinction parameters and distance from spectroscopic parallax
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
2- 12 A11 --- Name Star identification 16- 20 F5.2 mag Vmag Visual magnitude 25- 29 F5.2 mag Jmag J magnitude (1) 32- 35 F4.2 mag e_Jmag Error of J magnitude 40- 44 F5.2 mag Hmag H magnitude (1) 47- 50 F4.2 mag e_Hmag Error of H magnitude 55- 59 F5.2 mag Ksmag Ks magnitude (1) 62- 65 F4.2 mag e_Ksmag Error of Ks magnitude
Note (1): The above values come from the Point Source Catalogues of the First and the Second Data Releases.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Name Star identification 12 A1 --- n_Name [*] Individual note (1) 14- 20 A7 --- SpType MK Spectral type 23- 26 F4.2 mag E(B-V) E(B-V) colour excess 32- 35 F4.2 mag Av Extinction at V 38- 41 F4.2 mag e_Av Error of Av 44- 47 F4.2 --- Rv Total-to-selective extinction ratio, Rv=Av/E(B-V) 50- 53 F4.2 --- e_Rv Error of Rv 57- 63 A7 --- Assoc Stellar association name 67- 70 F4.1 kpc Dist Distance derived from spectroscopic parallax 74 A1 --- u_Rv [sl] See Note (2)
Note (1): - HD 1337 is an eclipsing binary of Beta Lyr type and it is known to have irregular variations. Polarization data indicate an envelope possibly related to mass exchange. - HD 35921 is an eclipsing binary of Beta Lyr type Note (2): Flag for Rv values that depart the average value by more than 2 sigma: "s" when Rv<3.19-2*0.50, "l" when Rv>3.19+2*0.50
Acknowledgements: Patrizio Patriarchi
(End) Patricia Bauer [CDS] 02-Sep-2003
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