Observations suggest that NSVS 254037 is an eclipsing variable star of W Ursae Majoris type. This star is located at α=00:28:28.0 δ=+78:57:42.7 and has the following alternate stellar designations: TYC 4500-730-1, NSVS 254037, [TNK2005] 3, GSC 04500-00730, 1RXS J002827.8+785750, 2MASS J00282798+7857426, [GGM2006] 254036, Gaia DR1 564727829363764992, and Gaia DR2 564727833661817472.  Star field with the target star and comparison stars used in ensemble differential photometry are shown in Figure 1.

Figure 1: Star field with ensemble stars used for differential photometry marked. The eclipsing variable star NSVS 254037 is marked by the green target (T₁). All ensemble stars are marked by the red apertures and designated the labels C₂-C₁₅. If a B band magnitude is known, it is given with each comparison. Field-scale is given on the left side of the image. Image is a representative image taken with the BSUO 20-inch telescope.

Observed Minus Calculated (O-C) Time of Minimum Analysis

Table 2: Heliocentric Julian dates [HJD] for times of minimum (first column) are reported along with 1σ error bars (second column). All times of minimum light are first determined for each filter (B, V, and R) light curve, and are determined by the method described by Kwee & van Woorden (1976). Similar times of minimum for differing filter light curves are averaged together and reported in column Times of Minimum. Eclipses are designated by primary for the primary eclipse and secondary for the secondary eclipse in the Eclipse column (third/middle column). Values of (O-C) (fourth column) are given in units of days along with 1σ errors (fifth column).

Best fitting Wilson-Devinney (WD) Models

Figure 4: Best-fit WD model fit with spots (red solid curve) to the folded light curve for differential B, V, and RC (from left to right) band magnitudes (top panel). The bottom panel shows the residuals from the best-fit WD model (red solid curve).

Derived System Parameters

Table 3: System parameters of NSVS 254037.  Column (1) gives the name of the parameter, (2) gives the parameter symbol and [units], (3) and (4) give the parameter value and error, respectively, without spots (ns), while (5) and (6) give the parameter value and error with spots (s). Some values aren’t dependent on spots and remain constant regardless, so the second instance is marked with a quotation mark (“). Any blanks in the table denote data which is, as of the last edit, unknown and/or unavailable.
^‡These values were calculated using the equations in Harmanec (1988). These equations assume our star(s) are main sequence, which is suspect. We only include the values as crude estimates, as spectral and radial velocity data will be required to obtain more certain values.

Table 4: Calculated O’Connell effect quanitites. The given filters are Johnson B (Filter 1), Johnson V (Filter 2), and Cousins
RC (Filter 3) with parameters an being specific Fourier fits. Paramters 2b1, IFT , and Iave are quantifying parameters in
terms of the difference in maxima of the light curve peaks (Figure 2). OER is the ratio of area under the light curve between
φ = 0.0 and φ = 0.5. The LCA measures deviance from symmetry of the two halves of the light curve as seen in Figure 2.

Presentations

Contact Information

All members of the Variable Star Research group are enthusiastic researchers with a passion for the work performed by the group. We are always happy to discuss any research projects and are always looking for like-minded and enthusiastic collaborators. For more information regarding any of the aforementioned research activities or the research activities of the Variable Star Research Group, please do not hesitate to contact Robert Berrington.