Interstellar Polarization Survey II: General Interstellar Medium

Abstract

Magnetic fields permeate the entire Galaxy and are essential to, for example, the regulation of several stages of the star formation process and cosmic ray transportation. Unraveling its properties, such as intensity and topology, is an observational challenge that requires combining different and complementary techniques. The polarization of starlight due to the absorption by field-aligned non-spherical dust grains provides a unique source of information about the interstellar magnetic field in the optical band. This work introduces a first analysis of a new catalog of optical observations of linearly polarized starlight in the diffuse interstellar medium (ISM), the Interstellar Polarization Survey, General ISM (IPS-GI). We used data from the IPS-GI, focusing on 38 fields sampling lines of sight in the diffuse medium. The fields are about 0.3${}^{\circ }$ by 0.3${}^{\circ }$ in size and each of them contains $\sim 1000$ stars on average. The IPS-GI catalog has polarimetric measurements of over 40000 stars, over 18000 of which have $P/{\sigma }_P>5$. We added distances and other parameters from auxiliary catalogs to over 36000 of these stars. We analyzed parameter distributions and correlations between parameters of a high-quality subsample of 10516 stars (i.e. $\sim 275$ stars per field). As expected, the degree of polarization tends to increase with the extinction, producing higher values of polarization at greater distances or at lower absolute Galactic latitudes. Furthermore, we find evidence for a large-scale ordered Galactic magnetic field.

arXiv comment19 pages, 15 figures, accepted for publication in AJ

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Cited by in corpus (6)

• Interstellar Polarization Survey III: Relation Between Optical Polarization and Reddening in the General Interstellar Medium
• Polarimeter to Unify the Corona and Heliosphere (PUNCH)
• The magnetic field of the Radcliffe Wave: starlight polarization at nearest approach to the Sun
• Multiwavelength high-resolution polarimetric imaging of second-generation disc around post-AGB binary IRAS 08544-4431 with SPHERE
• SPHERE/ZIMPOL insights into discs around evolved stars: arcs, asymmetries and dust properties
• TRIShUL: Technique for Reconstructing magnetic Interstellar Structure Using starLight polarization