Search

Start Over Subject polarimetry Capability Type Simple Cone Search
121. NGC6334 850um I, Q, U Stokes parameter maps
ID:
ivo://CDS.VizieR/J/A+A/647/A78
Title:
NGC6334 850um I, Q, U Stokes parameter maps
Short Name:
J/A+A/647/A78
Date:
21 Oct 2021
Publisher:
CDS
Description:
Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. We present new observations of the dust polarized emission at 850mum toward the 2pcx10pc map of NGC 6334 at a spatial resolution of 0.09pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-the-sky (POS) B-field angle ({chi}B_POS_) toward the whole region, along the 10pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and {chi}B_POS_ along the ridge crest and compared them with the results obtained from simulated filaments. The observations span ~3 orders of magnitude in I and PI and ~2 orders of magnitude in PF (from ~0.2% to ~20%). A large scatter in PI and PF is observed for a given value of I. Our analyzes show a complex B-field structure when observed over the whole region (~10pc); however, at smaller scales (~1pc), {chi}B_POS_ varies coherently along the crests of the filament network. The observed power spectrum of {chi}B_POS_ can be well represented with a power law function with a slope of -1.33+/-0.23, which is ~20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, {chi}B_POS_ rotates from being mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (N_H2_>~10^23^cm^-2^) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure. These observational results reveal for the first time the characteristics of the small-scale (down to ~0.1pc) B-field structure of a 10pc-long hub-filament system. Our analyzes show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.
122. NIR observations of GF 9/LDN 1082C field stars
ID:
ivo://CDS.VizieR/J/ApJ/867/79
Title:
NIR observations of GF 9/LDN 1082C field stars
Short Name:
J/ApJ/867/79
Date:
21 Oct 2021
Publisher:
CDS
Description:
The orientation of the magnetic field (B field) in the filamentary dark cloud GF 9 was traced from the periphery of the cloud into the L1082C dense core that contains the low-mass, low-luminosity Class 0 young stellar object (YSO) GF 9-2 (IRAS 20503+6006). This was done using SOFIA HAWC+ dust thermal emission polarimetry (TEP) at 216{mu}m in combination with Mimir near-infrared background starlight polarimetry (BSP) conducted in the H band (1.6{mu}m) and K band (2.2{mu}m). These observations were augmented with published I-band (0.77{mu}m) BSP and Planck 850{mu}m TEP to probe B-field orientations with offset from the YSO in a range spanning 6000au to 3pc. No strong B-field orientation change with offset was found, indicating remarkable uniformity of the B-field from the cloud edge to the YSO environs. This finding disagrees with weak-field models of cloud core and YSO formation. The continuity of inferred B-field orientations for both TEP and BSP probes is strong evidence that both are sampling a common B field that uniformly threads the cloud, core, and YSO region. Bayesian analysis of Gaia DR2 stars matched to the Mimir BSP stars finds a distance to GF 9 of 270+/-10pc. No strong wavelength dependence of B-field orientation angle was found, contrary to previous claims.
123. NIR photometry and polarization in NGC 2264
ID:
ivo://CDS.VizieR/J/ApJ/741/35
Title:
NIR photometry and polarization in NGC 2264
Short Name:
J/ApJ/741/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
Near-infrared imaging polarimetry in the J, H, and Ks bands has been carried out for the protostellar cluster region around NGC 2264 IRS 2 in the Monoceros OB1 molecular cloud. Various infrared reflection nebula clusters (IRNCs) associated with NGC 2264 IRS 2 and the IRAS 12 S1 core, as well as local infrared reflection nebulae (IRNe), were detected. The illuminating sources of the IRNe were identified with known or new near- and mid-infrared sources. In addition, 314 point-like sources were detected in all three bands and their aperture polarimetry was studied. Using a color-color diagram, reddened field stars and diskless pre-main-sequence stars were selected to trace the magnetic field (MF) structure of the molecular cloud. The mean polarization position angle of the point-like sources is 81+/-29{deg} in the cluster core, and 58+/-24{deg} in the perimeter of the cluster core, which is interpreted as the projected direction on the sky of the MF in the observed region of the cloud. The Chandrasekhar-Fermi method gives a rough estimate of the MF strength to be about 100uG. A comparison with recent numerical simulations of the cluster formation implies that the cloud dynamics is controlled by the relatively strong MF. The local MF direction is well associated with that of CO outflow for IRAS 12 S1 and consistent with that inferred from submillimeter polarimetry. In contrast, the local MF direction runs roughly perpendicular to the Galactic MF direction.
124. NIR polarimetry in the Central Molecular Zone
ID:
ivo://CDS.VizieR/J/ApJS/213/22
Title:
NIR polarimetry in the Central Molecular Zone
Short Name:
J/ApJS/213/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out near-infrared polarimetry toward the boundary of the Central Molecular Zone, in the field of (-1.{deg}4<~l<~-0.{deg}3 and 1.{deg}0<~l<~2.{deg}9,|b|<~0.{deg}1), using the near-infrared polarimetric camera SIRPOL on the 1.4m Infrared Survey Facility telescope. We have selected 112 intrinsically polarized sources on the basis of the estimate of interstellar polarization on Stokes Q/I-U/I planes. The selected sources are brighter than K_S_=14.5mag and have polarimetric uncertainty {delta}P<1%. Ten of these distinctive polarized sources are fit well with spectral energy distributions of young stellar objects when using the photometry in the archive of the Spitzer Space Telescope mid-infrared data. However, many sources have spectral energy distributions of normal stars suffering from heavy interstellar extinction; these might be stars behind dark clouds. Due to the small number of distinctive polarized sources and candidates of young stellar objects, we cannot judge if they are declining in number outside the Central Molecular Zone. Many massive candidates for young stellar objects in the literature have only small intrinsic polarization. This might suggest that their masses are 4-15M_{sun}_, whose intrinsic polarization has been expected to be small.
125. NIR polarimetry of sources near SgrA*
ID:
ivo://CDS.VizieR/J/A+A/534/A117
Title:
NIR polarimetry of sources near SgrA*
Short Name:
J/A+A/534/A117
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Galactic Center offers unique opportunities to study stellar and bow-shock polarization effects in a dusty environment. The goals of this work are to provide near-infrared (NIR) polarimetry of the stellar sources in the central parsec at the resolution of an 8m telescope for the first time, along with new insights into the nature of the known bright bow-shock sources. We use adaptive-optics assisted observations obtained at the ESO VLT in the H- and Ks-band, applying both high-precision photometric methods specifically developed for crowded fields and a newly established polarimetric calibration for NACO to produce polarization maps of the central 3"x10", in addition to spatially resolved polarimetry and a flux variability analysis on the extended sources in this region.
126. NIR sources in the northeastern part of LMC
ID:
ivo://CDS.VizieR/J/ApJS/222/2
Title:
NIR sources in the northeastern part of LMC
Short Name:
J/ApJS/222/2
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a near-infrared band-merged photometric and polarimetric catalog for the 39'x69' fields in the northeastern part of the Large Magellanic Cloud (LMC), which were observed using SIRPOL, an imaging polarimeter of the InfraRed Survey Facility. This catalog lists 1858 sources brighter than 14mag in the H band with a polarization signal-to-noise ratio greater than three in the J, H, or K_s_ bands. Based on the relationship between the extinction and the polarization degree, we argue that the polarization mostly arises from dichroic extinctions caused by local interstellar dust in the LMC. This catalog allows us to map polarization structures to examine the global geometry of the local magnetic field, and to show a statistical analysis of the polarization of each field to understand its polarization properties. In the selected fields with coherent polarization position angles, we estimate magnetic field strengths in the range of 3-25{mu}G using the Chandrasekhar-Fermi method. This implies the presence of large-scale magnetic fields on a scale of around 100 parsecs. When comparing mid- and far-infrared dust emission maps, we confirmed that the polarization patterns are well aligned with molecular clouds around the star-forming regions.
127. Observations of O and B stars
ID:
ivo://CDS.VizieR/J/ApJS/2/389
Title:
Observations of O and B stars
Short Name:
J/ApJS/2/389
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalog of O and B stars contains magnitudes, colors, spectral types and polarization for 1259 stars. In addition to observations, the catalogue contains the derived absorption and distance modulus. A photoelectric photometer attached to the 82-inch (2m) reflector of the McDonald Observatory was used for the polarization observations. The photometric UBV observations were made over a period of 4 years with the 13-inch (33cm) and the 82-inch telescopes at McDonald. The spectroscopic classification was made with a new camera installed on the Cassegrain spectrograph, with a dispersion of 86{AA}/mm at H{delta}.
128. Optical linear polarization at McDonald Obs.
ID:
ivo://CDS.VizieR/J/ApJS/194/19
Title:
Optical linear polarization at McDonald Obs.
Short Name:
J/ApJS/194/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 976 previously unpublished optical linear polarization measurements of quasars, active galactic nuclei, and some stars observed for interstellar polarization. The observations, covering the period 1981-2000, were made with McDonald Observatory's 2.1m Struve reflector and the Breger photopolarimeter.
129. Optically selected BL Lac candidates polarimetry
ID:
ivo://CDS.VizieR/J/A+A/529/A162
Title:
Optically selected BL Lac candidates polarimetry
Short Name:
J/A+A/529/A162
Date:
21 Oct 2021
Publisher:
CDS
Description:
195 polarimetric measurements of 182 BL Lac candidates from the SDSS taken with 3 different telescopes are presented. For each candidate the J2000 coordinates, its redshift, whether a source is listed in NED, the SDSS r-mag, the telescope for the observations used, the date of the observations, the exposure time for an individual exposure per position angle, the measured degree of polarization, the position angle and references to previous measurements of the sources are given. 13 objects have been observed twice. Here no entry for the coordinates is given. The redshifts, NED-listing and SDSS r-mags have been taken from Collinge et al. (2005, Cat. J/AJ/129/2542).
130. Optical Polarimetric Catalog for the SMC
ID:
ivo://org.gavo.dc/polcatsmc/q/cone
Title:
Optical Polarimetric Catalog for the SMC
Short Name:
PolCatSMC
Date:
27 Dec 2024 08:31:13
Publisher:
The GAVO DC team
Description:
An optical polarimetric catalog for the Small Magelanic Cloud (SMC) is presented. It gives intrinsic and observed polarizations in the V-band for a total of 7207 stars located in the Northeast and Wing sections of the SMC and part of the Magellanic Bridge.