J/A+AS/144/195 UBVRI polarimetric observations in NGC 6611 (Orsatti+, 2000)
Dust properties in NGC 6611
Orsatti A.M., Vega E.I., Marraco H.G.
<Astron. Astrophys. Suppl. Ser. 144, 195 (2000)>
=2000A&AS..144..195O 2000A&AS..144..195O
ADC_Keywords: Clusters, open ; Polarization ; Photometry, UBVRI
Keywords: dust - extinction - ISM: HII regions - ISM: magnetic fields -
Galaxy: open clusters and associations: individual: NGC 6611
Abstract:
An investigation on dust properties in the NW portion of NGC 6611 has
been conducted polarimetrically to test the existence of abnormal
extinction in that section of the open cluster in an independent way.
As previously suggested for the η Carinae nebula by Tapia et al.
(1988, in Conference on Dust in the Universe, Bailey M.E. and Williams
D.A. (eds.) Cambridge University Press, Cambridge, p.19) and
subsequently confirmed by Marraco et al. (1993), the canonical
relation between EV-K/EB-V and λmax (the wavelength of
maximum interstellar polarization) is not valid for stars belonging to
dusty HII regions, as is the case for the observed portion of M 16.
This may arise mainly from the presence of silicate grains of a
slightly larger size than the standard ISM and also from a
considerable increase in mean graphite grain size, according to
previous results from Chini & Wargau (1990A&A...227..213C 1990A&A...227..213C). About 50%
of the observed stars in NGC 6611 present indications of intrinsic
polarization in their measurements; a similar percentage was found in
IC 2944 (Vega et al., 1994AJ....108.1834V 1994AJ....108.1834V), another young open cluster
in close relation with an HII region.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
object.dat 26 39 Object positions from Simbad
table1.dat 81 195 UBVRI polarimetric observations
table1.tex 103 397 LaTeX version of table1
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See also:
J/A+AS/134/525 : NGC 6611 compiled catalog (Belikov+ 1999)
J/A+AS/121/223 : Multiphotometry of NGC 6611 (de Winter+ 1997)
Byte-by-byte Description of file: object.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- NGC6611 Star number (Walker, 1961ApJ...133..438W 1961ApJ...133..438W)
6- 7 I2 h RAh Right ascension (J2000.0)
9- 10 I2 min RAm Right ascension (J2000.0)
12- 15 F4.1 s RAs Right ascension (J2000.0)
17 A1 --- DE- Declination sign (J2000.0)
18- 19 I2 deg DEd Declination (J2000.0)
21- 22 I2 arcmin DEm Declination (J2000.0)
24- 25 I2 arcsec DEs Declination (J2000.0)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- NGC6611 Star number (Walker, 1961ApJ...133..438W 1961ApJ...133..438W)
NGC 6611 NNN in Simbad
4 A1 --- f_NGC6611 [*] *: star considered as being "frontside"
6- 32 A27 --- Name HD, BD or H designation (1)
34 A1 --- Band [UBVRI] Band (2)
36- 40 F5.2 % Pol Observed percentage polarisation
42- 45 F4.2 % e_Pol rms uncertainty on Pol
47- 51 F5.1 deg PA Observed position angle of the electric vector
53- 56 F4.1 deg e_PA rms uncertainty on PA
58- 59 I2 --- n ? Number of integrations
61- 64 F4.2 % PolI ? Intracluster percentage polarisation
66- 69 F4.2 % e_PolI ? rms uncertainty on PolI
71- 75 F5.1 deg PAI ? Intracluster position angle of the
electric vector
77- 81 F5.2 deg e_PAI ? rms uncertainty on PAI
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Note (1): Identifications from Henry Draper, Cat. III/135,
Bonner Durchmusterung, Cat. I/122 or
Hoag et al., 1961PUSNO..17..343H 1961PUSNO..17..343H.
Note (2): Wavelengths of the bands for which Pol and PA are measured:
U: 0.360µm
B: 0.440µm
V: 0.53µm
R: 0.690µm
I: 0.830µm
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Acknowledgements: Hugo Marraco
(End) Patricia Bauer [CDS] 04-May-2000