scholarly journals Polarization measurements in B5, L1 34 and Heiles Cloud 2 and evidence of newly born stars

1987 ◽  
Vol 122 ◽  
pp. 137-139
Author(s):  
U. C. Joshi ◽  
P. V. Kulkarni ◽  
M. R. Deshpande ◽  
A. Sen ◽  
A. K. Kulshrestha
Keyword(s):  
Magnetic Field ◽  
Polarization Measurement ◽  
Indian Institute ◽  
Dark Clouds ◽  
Polarization Measurements ◽  
University Of Arizona ◽  
Field Geometry ◽  
Formation And Evolution ◽  
The Magnetic Field

Polarization measurement of the background stars in the region of dark globules is important to study the magnetic field geometry and grants characteristics in the globule. These parameters are important for the formation and evolution of dark globules. We made Polarimetric observations of stars in three nearby dark clouds - B5, L134 and Heiles Cloud 2. Polarization measurements of stars in the region of B5 were made with ‘MINIPOL’ (Frecker and Serkowski, 1976) on 61″ telescope of University of Arizona. Observations for the stars in the region of L134 and Heiles Cloud 2 were made using PRL Polarimeter (Deshpande et al. 1985) on 1 meter telescope of Indian Institute of Astrophysics, Bangalore. Results are presented and discussed here. Figure 1 shows the polarization vectors projected on the sky plane for the above globules.

scholarly journals Dust properties and magnetic field geometry towards LDN 1570

2012 ◽  
Vol 10 (H16) ◽  
pp. 385-385
Author(s):  
C. Eswaraiah ◽  
G. Maheswar ◽  
A. K. Pandey
Keyword(s):  
Magnetic Field ◽  
Field Structure ◽  
Material Flows ◽  
Magnetic Field Structure ◽  
Cloud Structure ◽  
Photometric Observations ◽  
Field Geometry ◽  
Formation And Evolution ◽  
Field Lines ◽  
The Magnetic Field

AbstractWe have performed both optical linear polarimetric and photometric observations of an isolated dark globule LDN 1570 aim to study the dust polarizing and extinction properties and to map the magnetic field geometry so as to understand not only the importance of magnetic fields in formation and evolution of clouds but also the correlation of the inferred magnetic field structure with the cloud structure and its dynamics. Dust size indicators (RV and λmax) reveal for the presence of slightly bigger dust grains towards the cloud region. The inferred magnetic field geometry, which closely follows the cloud structure revealed by Herschel images, suggest that the cloud could have been formed due to converging material flows along the magnetic field lines.

scholarly journals Magnetic Field Structure in Dark Clouds

1987 ◽  
Vol 115 ◽  
pp. 48-50
Author(s):  
M. Tamura ◽  
T. Nagata ◽  
S. Sato ◽  
M. Tanaka ◽  
N. Kaifu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Mode ◽  
Polarization Degree ◽  
List Type ◽  
Dark Cloud ◽  
Dark Clouds ◽  
Central Regions ◽  
Field Geometry ◽  
Cloud Complex ◽  
The Magnetic Field

The magnetic field geometry in the central regions of two dark clouds has been mapped by measuring the polarization at 2.2 μm of background stars and of stars embedded in the clouds. The observations were done with the Kyoto polarimeter on the Agematsu 1m IR telescope in December 1984 for Heiles Cloud 2 in the Taurus dark cloud complex, and on the UKIRT 3.8m in May and July 1985 for the ρ Ophiuchus dark cloud core. The main results are: i)Most of the stars in both regions show polarization and their maxima are 2.7% in Heiles Cloud 2 and 7.6% in ρ Oph, respectively. There are similar positive relations between polarization degree and extinct ion Av's.ii)The distribution of position angles for Heiles Cloud 2 shows a single mode at about 50° and that for ρ Oph shows a bimode, at about 50° and 150°.iii)The magnetic fields, as delineated by the infrared polarization, appear perpendicular to the flattened elongations of the molecular clouds.

scholarly journals Near Infrared Polarimetry of Dark Clouds and Star Forming Regions - Two Micron Polarization Survey of T Tauri Stars

1990 ◽  
Vol 140 ◽  
pp. 327-328
Author(s):  
M. Tamura ◽  
S. Sato
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Near Infrared ◽  
Background Field ◽  
Star Forming ◽  
Dark Clouds ◽  
Star Forming Regions ◽  
Stellar Sources ◽  
Geometrical Relationship ◽  
The Magnetic Field

Infrared polarimetry is one of the most useful methods to delineate the magnetic field structure in dark clouds and star-forming regions, where the intracloud extinction is so large that optical polarimetry is inaccessible. We have been conducting a near-infrared polarization survey of background field stars and embedded sources toward nearby dark clouds and star-forming regions (Tamura 1988). Particularly, the magnetic field structure in the denser regions of the clouds are well revealed in Heiles Cloud 2 in Taurus, ρ Oph core, and NGC1333 region in Perseus (Tamura et al. 1987; Sato et al. 1988; Tamura et al. 1988). This survey also suggests an interesting geometrical relationship between magnetic field and star-formation: the IR polarization of young stellar sources associated with mass outflow phenomena is perpendicular to the magnetic fields. This relationship suggests a presence of circumstellar matter (probably dust disk) with its plane perpendicular to the ambient magnetic field. Combining with another geometrical relationship that the elongation of the denser regions of the cloud is perpendicular to the magnetic field, the geometry suggests that the cloud contraction and subsequent star-formation have been strongly affected by the magnetic fields. Thus, it is important to study the universality of such geometrical relationship between IR polarization of young stellar sources and magnetic fields. In this paper, we report the results on a 2 micron polarization survey of 39 T Tauri stars, 8 young stellar objects and 11 background field stars in Taurus dark cloud complex.

The magnetic field geometry of HD 215441

1978 ◽  
Vol 222 ◽  
pp. 226 ◽  
Author(s):  
E. F. Borra ◽  
J. D. Landstreet
Keyword(s):  
Magnetic Field ◽  
Field Geometry ◽  
The Magnetic Field

The Magnetic Field Geometry in DR 21

2003 ◽  
Vol 125 (3) ◽  
pp. 1418-1425 ◽  
Author(s):  
Terry Jay Jones ◽  
Hassib Amini
Keyword(s):  
Magnetic Field ◽  
Field Geometry ◽  
The Magnetic Field

scholarly journals Large-Scale Internal Magnetic Field of the Sun

1990 ◽  
Vol 138 ◽  
pp. 391-394
Author(s):  
A.E. Dudorov ◽  
V.N. Krivodubskij ◽  
A.A. Ruzmaikin ◽  
T.V. Ruzmaikina
Keyword(s):  
Magnetic Field ◽  
Differential Rotation ◽  
Large Scale ◽  
The Sun ◽  
Poloidal Magnetic Field ◽  
The Core ◽  
Torsional Waves ◽  
Formation And Evolution ◽  
Field Lines ◽  
The Magnetic Field

The behaviour of the magnetic field during the formation and evolution of the Sun is investigated. It is shown that an internal poloidal magnetic field of the order of 104 − 105 G near the core of the Sun may be compatible with differential rotation and with torsional waves, travelling along the magnetic field lines (Dudorov et al., 1989).

scholarly journals High-resolution spectropolarimetry of κ Cet: A proxy for the young Sun

2013 ◽  
Vol 9 (S302) ◽  
pp. 142-143
Author(s):  
J. D. do Nascimento ◽  
P. Petit ◽  
M. Castro ◽  
G. F. Porto de Mello ◽  
S. V. Jeffers ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Atmospheric Model ◽  
Longitudinal Component ◽  
Least Square ◽  
Doppler Imaging ◽  
Inversion Method ◽  
Radial Magnetic Field ◽  
Field Geometry ◽  
The Magnetic Field

Abstractκ1 Cet (HD 20630, HIP 15457, d = 9.16 pc, V = 4.84) is a dwarf star approximately 30 light-years away in the equatorial constellation of Cetus. Among the solar proxies studied in the Sun in Time, κ1 Cet stands out as potentially having a mass very close to solar and a young age. On this study, we monitored the magnetic field and the chromospheric activity from the Ca II H & K lines of κ1 Cet. We used the technique of Least-Square-Deconvolution (LSD, Donati et al. 1997) by simultaneously extracting the information contained in all 8,000 photospheric lines of the echelogram (for a linelist matching an atmospheric model of spectral type K1). To reconstruct a reliable magnetic map and characterize the surface differential rotation of κ1 Cet we used 14 exposures spread over 2 months, in order to cover at least two rotational cycles (Prot ~9.2 days). The Least Square deconvolution (LSD) technique was applied to detect the Zeeman signature of the magnetic field in each of our 14 observations and to measure its longitudinal component. In order to reconstruct the magnetic field geometry of κ1 Cet, we applied the Zeeman Doppler Imaging (ZDI) inversion method. ZDI revealed a structure in the radial magnetic field consisting of a polar magnetic spot. On this study, we present the fisrt look results of a high-resolution spectropolarimetric campaign to characterize the activity and the magnetic fields of this young solar proxy.

scholarly journals Magnetic field topology and chemical spot distributions of the Ap star HD 119419

2018 ◽  
Vol 609 ◽  
pp. A88 ◽  
Author(s):  
N. Rusomarov ◽  
O. Kochukhov ◽  
A. Lundin
Keyword(s):  
Magnetic Field ◽  
Open Cluster ◽  
Doppler Imaging ◽  
Clear Correlation ◽  
Stokes Vector ◽  
Chemical Abundance ◽  
Surface Field ◽  
Local Strength ◽  
Field Geometry ◽  
The Magnetic Field

Context. Analysis of high-resolution spectropolarimetric time-series observations of early-type magnetic stars is currently the most advanced method of obtaining detailed information on their surface magnetic field topologies and horizontal spot distributions. Aims. In this study we analyse a new set of high-quality full Stokes vector observations of the magnetic Ap star HD 119419 – a member of the 14 Myr old Lower Cen-Cru association – for the purpose of studying the surface field topology and mapping the chemical abundance spots. Methods. We made use of the circular and linear polarisation data collected for HD 119419 with the HARPSpol instrument at the ESO 3.6-m telescope. These observations were analysed with a multi-line magnetic diagnostic technique and modelled in detail with a Magnetic Doppler imaging (MDI) code. Results. We present a new set of high-precision mean longitudinal magnetic field measurements and derive a revised stellar rotational period by comparing our measurements with the literature data. We also redetermine the basic stellar atmospheric parameters. Our four Stokes parameter magnetic inversions reveal a moderately complex surface field topology with a mean field strength of 18 kG and a maximum local strength of 24 kG. A poloidal dipolar component dominates the magnetic energy spectrum of the surface field in HD 119419. However, significant contributions of the higher-order spherical harmonic components are also present. We show that the dipole plus quadrupole part of the reconstructed field geometry is incapable of reproducing the observed amplitudes and shapes of the Stokes Q and U profiles. The chemical abundance distributions of Fe, Cr, Ti, and Nd, derived self-consistently with the magnetic field geometry, are characterised by large abundance gradients and a lack of clear correlation with the magnetic field structure. Conclusions. This full Stokes vector analysis of HD 119419 extends the modern hot-star magnetic mapping investigations to an open cluster Ap star with a well-determined age. Further, MDI studies of cluster members will allow us to study the field topologies and chemical abundance spots as a function of stellar age.

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