J/ApJ/786/29 Catalog of distances to molecular clouds (Schlafly+, 2014)
A large catalog of accurate distances to molecular clouds from PS1 photometry.
Schlafly E.F., Green G., Finkbeiner D.P., Rix H.-W., Bell E.F.,
Burgett W.S., Chambers K.C., Draper P.W., Hodapp K.W., Kaiser N.,
Magnier E.A., Martin N.F., Metcalfe N., Price P.A., Tonry J.L.
<Astrophys. J., 786, 29 (2014)>
=2014ApJ...786...29S 2014ApJ...786...29S
ADC_Keywords: Diffuse clouds ; Molecular clouds ; Stars, distances
Keywords: dust, extinction; ISM: clouds
Abstract:
Distance measurements to molecular clouds are important but are often
made separately for each cloud of interest, employing very different
data and techniques. We present a large, homogeneous catalog of
distances to molecular clouds, most of which are of unprecedented
accuracy. We determine distances using optical photometry of stars
along lines of sight toward these clouds, obtained from PanSTARRS-1.
We simultaneously infer the reddenings and distances to these stars,
tracking the full probability distribution function using a technique
presented in Green et al. (2014ApJ...783..114G 2014ApJ...783..114G). We fit these
star-by-star measurements using a simple dust screen model to find the
distance to each cloud. We thus estimate the distances to almost all
of the clouds in the Magnani et al. (1985ApJ...295..402M 1985ApJ...295..402M, MBM)
catalog, as well as many other well-studied clouds, including Orion,
Perseus, Taurus, Cepheus, Polaris, California, and Monoceros R2,
avoiding only the inner Galaxy. Typical statistical uncertainties in
the distances are 5%, though the systematic uncertainty stemming from
the quality of our stellar models is about 10%. The resulting catalog
is the largest catalog of accurate, directly measured distances to
molecular clouds. Our distance estimates are generally consistent with
available distance estimates from the literature, though in some cases
the literature estimates are off by a factor of more than two.
Description:
Distance estimates to molecular clouds along 232 lines of sight,
chosen to pass through MBM clouds and major molecular clouds at high
Galactic latitudes and in the outer Galaxy. Along each line of sight,
parameters describing the distance to the cloud, the foreground
reddening, and the cloud reddening have been measured. The full Markov
Chain Monte Carlo (MCMC) chain in the analysis is also provided.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
bigcloud.dat 142 125 Distances to major molecular clouds
mbmcloud.dat 142 107 Distances to MBM clouds (1985ApJ...295..402M 1985ApJ...295..402M)
bigcloud.fits 2880 27788 *FITS version with arrays (78154KB)
mbmcloud.fits 2880 23787 *FITS version with arrays (66901KB)
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Note on bigcloud.fits and mbmcloud.fits:
The last columns (chain and lnprob, not included in the .dat versions)
contain two arrays:
* chain, array of 3x20000, lists the 3 parameters (distance modulus,
normalization, and foreground reddening) of each of the 20000 points
of the Markov Chain Monte Carlo (MCMC) chain;
* lnprob, array of 20000, corresponds to the lof of the likelihood of
the points on the chain.
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Byte-by-byte Description of file: bigcloud.dat mbmcloud.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of sky region of sight line
12- 19 F8.4 deg GLON Galactic longitude (l)
21- 28 F8.4 deg GLAT Galactic latitude (b)
30- 38 F9.7 mag E(B-V) Median E(B-V) of Planck map toward stars (medebv)
40- 48 F9.6 mag m16 16th percentile distance modulus
50- 58 F9.6 mag m50 50th percentile distance modulus
60- 68 F9.6 mag m84 84th percentile distance modulus
70- 78 F9.7 --- n16 16th percentile map normalization factor
80- 88 F9.7 --- n50 50th percentile map normalization factor
90- 98 F9.7 --- n84 84th percentile map normalization factor
100-111 F12.10 mag f16 16th percentile foreground reddening
113-123 F11.9 mag f50 50th percentile foreground reddening
125-135 F11.9 mag f84 84th percentile foreground reddening
137 I1 --- ft [1/2] fit type: 1=small beam (0.2°) used,
2=large beam (0.7°) used (fittype)
139-142 I4 --- N* [20/1083] Number of stars used in analysis
(nstar_tot)
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Acknowledgements:
Eddie Schlafly, schlafly(at)mpia.de
(End) Eddie Schlafly [MPIA, Germany], Patricia Vannier [CDS] 10-Sep-2014