Romanov V48: unusual intermediate polar in the period gap

TL;DR

Romanov V48 is identified as an unusual intermediate polar within the period gap, exhibiting large spin variations and spectral features that suggest it may be an intermediate object between polars and intermediate polars.

Contribution

This study reclassifies Romanov V48 as an intermediate polar in the period gap, revealing unique spectral and variability characteristics that challenge existing classifications.

Findings

Romanov V48 has an orbital period of 0.102312 days.

The system exhibits a large spin variation amplitude of 0.6 mag.

Infrared emission suggests similarities to polars, indicating a possible intermediate nature.

Abstract

We studied Romanov V48, which had been considered as a possible polar below the period minimum (orbital period of 0.0420991 d). We analyzed the publicly available Zwicky Transient Facility data and found that this object is an intermediate polar with an orbital period of 0.102312 d (in the period gap) and a spin period of 0.0420991 d. The amplitude of the spin variation was very large (0.6 mag) and the profile has been confirmed to vary with the beat period of 0.071534 d. The ratio between the spin and orbital periods was large and the system resembles the intermediate polar DW Cnc below the period gap. Infrared emission from Romanov V48, however, could not be explained by radiation from the secondary. The infrared excess and the shape of the spectral energy distribution resembled those of polars, suggesting that the emission mechanism in Romanov V48 is similar to those of polars. Romanov V48 may be an intermediate object between intermediate polars and polars.