J/A+A/690/A49 Linear polarization of 5 open clusters (Uppal+, 2024)
Linear polarization study of open clusters towards the anticenter direction:
Signature of the spiral arms.
Uppal N., Ganesh S., Pelgrims V., Joshi S., Sarkar M.
<Astron. Astrophys. 690, A49 (2024)>
=2024A&A...690A..49U 2024A&A...690A..49U (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, open ; Interstellar medium ; Polarization
Keywords: methods: observational - techniques: polarimetric - dust, extinction -
open clusters and associations: general - Galaxy: structure
Abstract:
Our objective is to investigate the distribution of dust and
associated large-scale structures of the Galaxy using optical linear
polarization measurements of various open clusters located at
different distances in the Galactic anticenter direction.We present
R-band linear polarization observations of stars towards five open
clusters: Kronberger 1, Berkeley 69, Berkeley 71, Berkeley 19, and
King 8 in the anticenter direction. The polarization observations were
carried out using ARIES IMaging POLarimeter mounted on the 104cm
Sampurnanand telescope of ARIES, Nainital, making it the first study
to target the polarization observations towards distant clusters
(∼6kpc). We combined the observed polarization data with the distance
information from the Gaia space telescope to infer the dust
distribution along the line of sight.The variation in the degree of
polarization and extinction with distance reveals the presence of
multiple dust layers along each cluster direction. In addition, common
foreground dust layers detected towards different cluster directions
highlight the presence of global features such as spiral arms. Our
results show that the dust clouds at 2kpc towards Berkeley 69 and
Berkeley 71 coincide with the Perseus arm, while the dust layer at
∼4kpc towards distant clusters, Berkeley 19 and King 8, indicates the
presence of the Outer arm. The large-scale dust distribution obtained
by combining our polarization results with the previous polarization
studies of nearby open clusters suggests that the anticenter direction
is characterized by low extinction, homogeneous dust distribution with
somewhat uniform orientation of the plane-of-sky component of the
magnetic field along the line of sight.Our study demonstrates the
utility of polarization as a tool to study the large-scale dust
distribution and structural features where the kinematic distance
methods are inadequate to provide accurate distances to the dust
clouds. The global dust distribution towards the anticenter direction
shows signatures of the intervening spiral arms.
Description:
We present five tables corresponding to the R-band linear polarization
measurements of stars observed towards five open clusters,
Kronberger 1, Berkeley 69, Berkeley 71, King 8, and Berkeley 19. These
observations were carried out using ARIES IMaging POLarimeter (AIMPOL)
mounted on 1.04 m Sampunanand telescope at Aryabhatta Research
Institute of Observational Sciences (ARIES), Nainital, India from
October 19, 2022 to October 23, 2022. Each file named after the
respective cluster, contain the polarization measurements of all the
stars observed towards that cluster with polarization signal-to-noise
more than 3. The Source column in all the files corresponds to the
Gaia DR3 Source IDs (Cat. I/355).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
kron1.dat 89 158 Kronberger 1 polarization measurements
berk69.dat 89 151 Berkeley 69 polarization measurements
berk71.dat 89 80 Berkeley 71 polarization measurements
king8.dat 89 161 King 8 polarization measurements
berk19.dat 89 88 Berkeley 19 polarization measurements
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia collaboration, 2022)
Byte-by-byte Description of file: *.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 Source ID
21- 28 F8.5 deg RAdeg Right Ascension (J2000)
30- 37 F8.5 deg DEdeg Declination (J2000)
39- 42 F4.2 % Pobs Degree of polarization
44- 47 F4.2 % e_Pobs Degree of polarization error
49- 52 F4.2 % P Debiased degree of polarization
54- 58 F5.1 deg theta Polarization angle
60- 63 F4.1 deg e_theta Polarization angle error
65- 70 F6.3 --- q q normalized Stokes parameter
72- 76 F5.3 --- e_q q Stokes parameter error
78- 83 F6.3 --- u u normalized Stokes parameter
85- 89 F5.3 --- e_u u normalized Stokes parameter error
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Acknowledgements:
Namita Uppal, namita(at)ia.forth.gr
(End) Patricia Vannier [CDS] 12-Aug-2024