Time-resolved Spectroscopy of the Polar EU Cancri in the Open Cluster Messier 67

Abstract

We present time-resolved spectroscopic and polarimetric observations of the AM Her system EU Cnc. EU Cnc is located near the core of the old open cluster Messier 67; new proper motion measurements indicate that EU Cnc is indeed a member of the star cluster, this system therefore is useful to constrain the formation and evolution of magnetic cataclysmic variables. The spectra exhibit two-component emission features with independent radial velocity variations as well as time-variable cyclotron emission indicating a magnetic field strength of 41 MG. The period of the radial velocity and cyclotron hump variations are consistent with the previously-known photometric period, and the spectroscopic flux variations are consistent in amplitude with previous photometric amplitude measurements. The secondary star is also detected in the spectrum. We also present polarimetric imaging measurements of EU Cnc that show a clear detection of polarization, and the degree of polarization drops below our detection threshold at phases when the cyclotron emission features are fading or not evident. The combined data are all consistent with the interpretation that EU Cnc is a low-state polar in the cluster Messier 67. The mass function of the system gives an estimate of the accretor mass of M_WD >= 0.68 M_sun with M_WD ~ 0.83 M_sun for an average inclination. We are thus able to place a lower limit on the progenitor mass of the accreting WD of >= 1.43 M_sun.

Accepted for publication in the Astronomical Journal. 9 pages, 5 figures, uses emulateapj

References in corpus (8)

• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• The Initial-Final Mass Relation: Direct Constraints at the Low Mass End
• Found: The missing blue opacity in atmosphere models of cool hydrogen white dwarfs
• Deep MMT Transit Survey of the Open Cluster M37 II: Variable Stars
• The initial-final mass relationship from white dwarfs in common proper motion pairs
• The end of the white dwarf cooling sequence in M 67
• Variable stars in the open cluster NGC 6791 and its surrounding field
• VV Pup in a low state: secondary-star irradiation or stellar activity?

Cited by in corpus (3)

• Magnetic White Dwarfs
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• One thousand cataclysmic variables from the Catalina Real-time Transient Survey