Researchers: Melanie Isenbarger, Ashlee Martin

Observations suggest that NSVS 6103255 is an eclipsing variable star of W Ursae Majoris type. This star is located at α=22:29:35.20 δ=+37:57:31.44 and has the following alternate stellar designations: HD 213271, AG+37 2224, BD+37 4591, GSC 0200-01872, 2MASS J22293519+3757313, PPM 87838, SAO 72394, TIC 120530488, TYC 3200-1872-1, V* V678 Lac, Gaia DR2 1907779946960802944, Gaia DR1 1907779942662517120, Gaia DR3 1907779946960802944.
We have observed this star with the Ball State University Observatory (BSUO) 20-inch (0.5m) telescope in the Johnson B (B) & V (V), and Cousins R (Rc) bandpasses. All data collected is from September 3rd, 2019, to October 1st, 2019. All stellar photometry is performed by the AstroImageJ (AIJ) software package using similar ensemble stars. A radec file of known calibrated magnitudes for possible comparison stars is downloaded from the Eclipsing Binaries Software Package. Known magnitudes are then utilized by AIJ to calibrate the magnitude of the target star. All photometry is done in magnitude and BJD_TDB. The star field from the R band with the target star and comparison stars used in ensemble differential photometry is shown in Figure 1. Using Eclipsing Binaries, Transiting Exoplanet Satellite Survey (TESS) data was found for NSVS 6103255. Out of three sectors, only one was usable, Sector 16. This data was taken from September 12th, 2019, to October 6th, 2019. The star field from the TESS data with the target star and comparison stars used in ensemble differential photometry is shown in Figure 2.

Figure 1 (Left): BSUO star field with ensemble stars used for differential photometry marked. The eclipsing variable star NSVS 6103255 is marked by the green target (T1). All ensemble stars are marked by the red apertures and designated C2-C5. If a B, V, or Rc band magnitude is known, it is given with each comparison star in Table 1.

Figure 2 (Right): TESS star field with ensemble stars used for differential photometry marked. The eclipsing variable star NSVS 6103255 is marked by the green target (T1). All ensemble stars are marked by the red apertures and designated C2-C5. If a TESS band magnitude is known, it is given with each comparison star in Table 2.
(J2000.0) Magnitudes
Star Catalog α δ B V Rc
T1 HD 231271 22:29:35.20 +37:57:31.45 9.53 9.06 9.13
C2 TYC 3200-616-1 22:29:35.21 +37:58:10.98 12.84 11.25 10.43
C3 — 22:29:13.22 +38:02:12.19 12.82 12.35 12.07
C4 — 22:29:09.02 +38:02:55.05 12.57 11.84 11.41
C5 TYC 3201-471-1 22:30:27.02 +38:06:08.51 12.37 11.34 10.79

Table 1: BSUO target and comparison stars catalogs, right ascensions, declinations, and magnitudes.
(J2000.0) Magnitudes
Star Catalog α δ T
T1 HD 231271 22:29:35.33 +37:57:48.63 10.05
C2 — 22:30:34.41 +37:49:26.45 12.35
C3 — 22:30:33.53 +37:54:08.30 99.99
C4 — 22:28:23.17 +37:55:17.89 10.74
C5 — 22:29:03.51 +38:04:48.41 99.99
Table 2: TESS target and comparison stars catalogs, right ascensions, declinations, and magnitudes. Notice there are no catalogs for these stars, as most are multiple stars in one cluster, making it hard to determine which stars are being analyzed.
Color Light Curve

Figure 3: Color light curve of B, V, and Rc bands. The B band is blue, the V band is green, and the Rc band is red. The B-V and V-Rc plots are also shown. The B-V plot was used to determine the temperature of the primary star to be 7279 ± 120.1678 K.
Observed-Minus-Calculated Plot
Figure 4: O-C Plot of NSVS 6103255. We plotted the O-C values versus the epoch number with their errors from both BSUO, in orange, and TESS, in blue, data of NSVS 6103255. These values show that the determined period reported in the conclusion section is consistent with the observed data. There is little evidence for a slight offset in determining the epoch.

Best fitting PHysics of Eclipsing BinariEs (PHOEBE) Models
All modeling is performed using the PHysics Of Eclipsing BinariEs (PHOEBE) (v2.4.22) software package. PHOEBE is a graphical user interface (GUI) to the WD code that is used to model binary stars. Figure 5 shows the best-fit PHOEBE model with seven star spots included. Figure 6 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] 0.62637363
Epoch T0 [HJD]
Inclination i [deg]
Surface Temp. Teff,1 [K] 6800
Teff,2 [K]
Surface Potential Ω1,2 [-]
Mass Ratio q [-]
Stellar Mass‡ M1 [M☉] 1.4
M2 [M☉]
Semi-major Axis‡ a [R☉]

Table 3: System parameters of NSVS 6103255.  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 Melanie Isenbarger at national, regional, and local conferences for NSVS 6103255 are given below.

  1. NSVS 6103255. Ball State University Physics & Astronomy colloquium, December 5, 2019.

Poster presentations and talks given by Ashlee Martin at national, regional, and local conferences for NSVS 6103255 are given below.

  1. O-C and Period Analysis of NSVS 6103255. Indiana Academy of Science, March 22nd, 2025.
  2. O-C Period Analysis of NSVS 6103255. Ball State University Physics & Astronomy colloquium, April 17th, 2025.
  3. Numerical Modeling of the Third Light in NSVS 6103255. Indiana Academy of Science, March 21st, 2026.

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.