Polarization towards the young open cluster NGC 6823

Medhi, Biman J.; Maheswar, G.; Pandey, J. C.; Tamura, Motohide; Sagar, Ram

doi:10.1111/j.1365-2966.2010.16221.x

Cited by 24 publications

(22 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The instrumental polarization of AIMPOL on the 1.04-m ST has been monitored since 2004 for different projects and is 0.1% in different bands (e.g., Rautela et al 2004;Medhi et al 2007Medhi et al , 2008Medhi et al , 2010Eswaraiah et al 2011Eswaraiah et al , 2012. No correction for the instrumental polarization was applied to the data obtained with IFOSC since the instrumental polarization of the instrument on the 2-m telescope is <0.05 per cent.…”

Section: Polarimetrymentioning

confidence: 99%

A study of the starless dark cloud LDN 1570: Distance, dust properties, and magnetic field geometry

Eswaraiah

Maheswar

Pandey

et al. 2013

A&A

View full text Add to dashboard Cite

Aims. We aim to map the magnetic field geometry and to study the dust properties of the starless cloud, L1570, using multi-wavelength optical polarimetry and photometry of the stars projected on the cloud. Methods. The direction of the magnetic field component parallel to the plane of the sky of a cloud can be obtained using polarimetry of the stars projected on and located behind the cloud. It is believed that the unpolarized light from the stars background to the cloud undergoes selective extinction while passing through non-spherical dust grains that are aligned with their minor axes parallel to the cloud magnetic field. The emerging light becomes partially plane polarized. The observed polarization vectors trace the direction of the projected magnetic field of the cloud. We made R-band imaging polarimetry of the stars projected on a cloud, L1570, to trace the magnetic field orientation. We also made multi-wavelength polarimetric and photometric observations to constrain the properties of dust in L1570. Results. We estimated a distance of 394 ± 70 pc to the cloud using 2MASS JHK s colors. Using the values of the Serkowski parameters, σ 1 , , λ max , and the position of the stars on the near-infrared color-color diagram, we identified 13 stars that could possibly have intrinsic polarization and/or rotation in their polarization angles. One star, 2MASS J06075075+1934177, which is a B4Ve spectral type, shows diffuse interstellar bands in the spectrum in addition to the Hα line in emission. There is an indication for slightly bigger dust grains toward L1570 on the basis of the dust grain size-indicators such as λ max and R V values. The magnetic field lines are found to be parallel to the cloud structures seen in the 250 μm images (also in the 8 μm and 12 μm shadow images) of L1570. Based on the magnetic field geometry, the cloud structure, and the complex velocity structure, we conclude that L1570 is in the process of formation due to the converging flow material mediated by the magnetic field lines. A structure function analysis showed that in the L1570 cloud region the large-scale magnetic fields are stronger than the turbulent component of the magnetic fields. The estimated magnetic field strengths suggest that the L1570 cloud region is subcritical and hence could be strongly supported by the magnetic field lines.

show abstract

Section: Polarimetrymentioning

confidence: 99%

A study of the starless dark cloud LDN 1570: Distance, dust properties, and magnetic field geometry

Eswaraiah

Maheswar

Pandey

et al. 2013

A&A

View full text Add to dashboard Cite

show abstract

“…In the majority of polarimetric studies of open clusters, it was found that the alignments of polarization vectors are almost parallel to the direction of the Galactic plane (e.g. Martínez et al 2004;Vergne et al 2007;Medhi et al 2007;Orsatti et al 2010;Medhi et al 2010;Eswaraiah et al 2011), while toward some other lines of sight, the second component of the magnetic field was also found, which was slightly inclined to the Galactic plane (Medhi et al 2008;Eswaraiah et al 2012). Davis & Greenstein (1951) suggested the dominant mechanism for alignment of dust grains in the ISM could be due to the presence of the small non-conservative torque produced by paramagnetic relaxation, and that this torque tends to align the short axis of the rapidly spinning grain along the magnetic field.…”

Section: Results Analysis and Discussionmentioning

confidence: 99%

Optical Linear Polarization toward the Open Star Cluster Casado Alessi 1

Singh

Pandey

Yadav

et al. 2020

Self Cite

View full text Add to dashboard Cite

We present B-, V-, R-, and I-bands linear polarimetric observations of 73 stars in the direction of open star cluster Casado Alessi 1 (hereafter Alessi 1). We aim to use polarimetry as a tool to investigate the properties and distribution of dust grains toward the direction of the cluster. The polarimetric observations were carried out using the ARIES IMaging POLarimeter mounted at the 104 cm telescope of ARIES, Nainital (India). Using the Gaia photometric data the age and distance of the cluster are estimated to be 0.8 ± 0.1 Gyr and 673 ± 98 pc, respectively. A total of 66 stars with a 26 radius from the cluster are identified as members of the cluster using the astrometric approach. Out of these 66 members, 15 stars were observed polarimetrically and found to have the same value of polarization. The majority of the stars in the region follow the general law of the polarization for the interstellar medium, indicating that polarization toward the cluster Alessi 1 is dominated by foreground dust grains. The average values of the maximum polarization (P max ) and the wavelength corresponding to the maximum polarization (λ max ) toward the cluster are found to be 0.83±0.03 % and 0.59±0.04 µm, respectively. Also, dust grains toward the cluster appear to be aligned, possibly due to the galactic magnetic field.

show abstract

“…The gain and the read-out noise of the CCD are 11.98 e − /ADU and 7.0 e − , respectively. Four sets of exposures of each 60 s were made on both the nights of observation.The detailed description of the instrument is given in Rautela et al (2004) and Medhi et al (2008Medhi et al ( , 2010.…”

Section: Observation and Data Reductionmentioning

confidence: 99%