J/ApJ/708/1628 Diffuse interstellar bands. IV. (McCall+, 2010)
Studies of the diffuse interstellar bands.
IV. The nearly perfect correlation between λλ6196.0 and 6613.6.
McCall B.J., Drosback M.M., Thorburn J.A., York D.G., Friedman S.D.,
Hobbs L.M., Rachford B.L., Snow T.P., Sonnentrucker P., Welty D.E.
<Astrophys. J., 708, 1628-1638 (2010)>
=2010ApJ...708.1628M 2010ApJ...708.1628M
ADC_Keywords: Interstellar medium ; Equivalent widths ; Spectroscopy ;
Stars, early-type
Keywords: ISM: lines and bands - ISM: molecules
Abstract:
In a sample of 114 diffuse cloud sightlines spanning a wide range of
interstellar environments, we find the equivalent widths of the
diffuse interstellar bands (DIBs) λ6196.0 and λ6613.6 to
be extremely well correlated, with a correlation coefficient of 0.986.
A maximum likelihood functional relationship analysis shows that the
observations are consistent with a perfect correlation if the
observational errors, which are dominated by continuum placement and
other systematics such as interfering lines, have been underestimated
by a factor of 2. The quality of this correlation far exceeds other
previously studied correlations, such as that between the
λ5780.5 DIB and either the color excess or the atomic hydrogen
column density. The unusually tight correlation between these two DIBs
would seem to suggest that they might represent the first pair of DIBs
known to be due to the same molecular carrier. However, further
theoretical work will be required to determine whether the different
linewidths and band shapes of these two DIBs can be consistent with a
common carrier. If the two DIBs do not in fact share the same
molecular carrier, their two carriers must be chemically very closely
related.
Description:
The data used in this study were obtained using the Astrophysical
Research Consortium Echelle Spectrograph (ARCES) at the 3.5m telescope
at Apache Point Observatory between 1999 and 2003. The ARCES
spectrograph has a resolving power of 38000 (corresponding to a
velocity resolution of approximately 8km/s).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 114 Physical properties and equivalent width
measurements for program stars
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See also:
II/135 : Suppl. to Diffuse Interstellar Band Measurements (Guarinos 1988)
II/149 : Diffuse Interstellar Band Measurements (Snow+ 1977)
J/ApJ/705/32 : Diffuse interstellar bands from HD 183143 (Hobbs+, 2009)
J/MNRAS/358/563 : Diffuse Interstellar Bands in 49 stars (Megier+, 2005)
J/A+A/414/949 : Interstellar bands and H2, CH, CO column densities
(Weselak+ 2004)
J/ApJS/93/211 : IUE survey of H I Lyα absorption. I. (Diplas+ 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name
12- 20 A9 --- SpType MK spectral type
22- 25 F4.2 mag E(B-V) (B-V) color excess (1)
27 A1 --- l_logNH Limit flag on NH
28- 32 F5.2 [cm-2] logNH ? Log of Hydrogen column density
34- 37 F4.2 [cm-2] e_logNH ? NH uncertainty
39- 43 F5.2 [cm-2] logNH2 ? Log of H2 column density
45- 48 F4.2 [cm-2] e_logNH2 ? NH2 uncertainty
50 I1 --- r_logNH ? Reference for N(H) (2)
52- 53 I2 --- r_logNH2 ? Reference for N(H2) (2)
55- 59 F5.1 10-13m W6196 6196.0 equivalent width (in mÅ)
61- 63 F3.1 10-13m e_W6196 W6196 uncertainty
65- 69 F5.1 10-13m W6613 6613.6 equivalent width (in mÅ)
71- 74 F4.1 10-13m e_W6613 W6613 uncertainty
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Note (1): The calculated E(B-V) values are based on the intrinsic colors from
Johnson, H.L. (1963, Basic Astronomical Data, ed. K. A. Strand
(Chicago, IL: Univ. Chicago Press), 214).
Note (2): References as follows :
1 = Diplas & Savage 1994, Cat. J/ApJS/93/211, Table 1;
2 = Diplas & Savage 1994, Cat. J/ApJS/93/211, Table 2;
3 = Shull & van Steenberg 1985ApJ...294..599S 1985ApJ...294..599S, Table 1;
4 = Shull & van Steenberg 1985ApJ...294..599S 1985ApJ...294..599S, Table 2;
5 = Bohlin et al. 1978ApJ...224..132B 1978ApJ...224..132B;
6 = Savage, et al. 1977ApJ...216..291S 1977ApJ...216..291S;
7 = Spitzer et al. 1974ApJS...28..373S 1974ApJS...28..373S;
8 = Rachford et al. 2002ApJ...577..221R 2002ApJ...577..221R;
9 = B. L. Rachford, private communication;
10 = Rachford et al. 2009ApJS..180..125R 2009ApJS..180..125R.
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History:
From electronic version of the journal
References:
Thorburn et al. Paper I. 2003ApJ...584..339T 2003ApJ...584..339T
Hobbs et al. Paper II. 2008ApJ...680.1256H 2008ApJ...680.1256H
Hobbs et al. Paper III. 2009ApJ...705...32H 2009ApJ...705...32H, Cat. J/ApJ/705/32
Friedman et al. Paper V. 2011ApJ...727...33F 2011ApJ...727...33F
(End) Emmanuelle Perret [CDS] 22-Feb-2012