Researchers: Richard Gorby, Hanbit Lee

Observations suggest that NSVS 3350218 is an eclipsing variable star of W Ursae Majoris type. This star is located at α=22:11:14.54 δ=+66:02:16.19 and has the following alternate stellar designations:  2MASS J22111454+6602162, Gaia DR2 2218887449236109824.  Star field with the target star and comparison stars used in ensemble differential photometry are shown in Figure 1.

Star Field
Figure 1: Star field including marked ensemble stars. The variable star NSVS 3350218 is marked by the green aperture (T1). Ensemble stars (C2-C11) are marked by red apertures.

Best fitting Wilson-Devinney (WD) Models

All modeling is performed using the PHysics Of Eclipsing BinariEs (PHOEBE) (v0.31a) software package. PHOEBE is a graphical user interface (gui) to the WD code that is used to model binary stars. Figure 3 shows the best fit WD model with two star spots included. Figure 4 shows a graphical representation of the stellar surface.

Derived System Parameters
Below is a Table 3, which lists parameters and their values derived in the analysis of this system via the methods discussed above.

No Spots Spots
Parameter Symbol [unit] Value Error Value Error
(1) (2) (3) (4) (5) (6)
Period P [days] 0.316778 0.000382
Epoch T0 [HJD]
Inclination i [deg]
Surface Temp. Teff,1 [K] 9616 1133
Teff,2 [K]
Surface Potential Ω1,2 [-]
Mass Ratio q [-] 0.863
Stellar Mass‡ M1 [M☉]
M2 [M☉]
Semi-major Axis‡ a [R☉]

Table 3: System parameters of NSVS 3350218.  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 (no spots), while (5) and (6) give the parameter value and error with spots (spots). Any blanks in the table denote data which is, as of the last edit, unknown and/or unavailable. Please note that these parameters may change as the modeling of the system progresses.
‡These values were calculated using the 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.

Presentations
Poster presentations and talks given by Richard Gorby at national, regional and local conferences for NSVS 3350218 are given below.

  1. A Photometric Study of the Eclipsing Binary Star NSVS 3350218. Ball State University Physics & Astronomy colloquium, November 21, 2019.

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.