DISCOVERY OF POLARIZED EMISSION FROM TWO SOFT X-RAY-EMITTING INTERMEDIATE POLARS: UU Col AND NY Lup

Journal Article · Sat Nov 20 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/724/1/165· OSTI ID:21471204

Katajainen, S; Lehto, H J; Berdyugin, A ^[1]; Butters, O; Norton, A J ^[2]; Piirola, V ^[3]

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1. Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Vaisalantie 20, FI-21500, Piikkio (Finland)
2. Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)
3. Finnish Centre for Astronomy with ESO, Vaisalantie 20, FI-21500, Piikkio (Finland)

We aim to investigate the magnetic field strengths and cyclotron emission of the two soft X-ray-emitting intermediate polars (IPs) UU Col and NY Lup. We study the connection between polars and soft X-ray-emitting IPs by searching for evidence of circularly polarized light in these two systems, which may be examples of progenitors of polars. We carried out photopolarimetric observations of our targets using the Very Large Telescope (UT2) and FORS1 at Paranal. Imaging polarimetry with good signal-to-noise and relatively high time resolution is possible for these targets using such a large telescope. Detection of circular polarization, modulated according to a white dwarf (WD) spin period, is clear evidence of cyclotron emission processes near the WD surface. The color dependence of the polarization allows us to make estimates of the magnetic field strength. We found that both UU Col and NY Lup emit circularly polarized light in the B and I bands, modulated at the spin period of the WD in each case. We add further confirmation to the idea that soft X-ray-emitting IPs emit circularly polarized light and that cyclotron emission plays an important role in these systems. This also suggests that some soft X-ray-emitting IPs might be progenitors of polars.

• OSTI ID: 21471204
• Journal Information: Astrophysical Journal, Vol. 724, Issue 1; Other Information: DOI: 10.1088/0004-637X/724/1/165; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTROPHYSICS
EMISSION
MAGNETIC FIELDS
NOVAE
POLARIMETRY
POLARIZATION
SOFT X RADIATION
TELESCOPES
TIME RESOLUTION
WHITE DWARF STARS
BINARY STARS
DWARF STARS
ELECTROMAGNETIC RADIATION
ERUPTIVE VARIABLE STARS
IONIZING RADIATIONS
PHYSICS
RADIATIONS
RESOLUTION
STARS
TIMING PROPERTIES
VARIABLE STARS
X RADIATION