Monitoring and identification of the variable components of HD 83742 / HD 302301
Abstract:
HD 83742 / HD 302301 is a visual binary, one component of which is an eclipsing binary and one of which shows delta Scuti (DSCT) pulsations. This small amplitude eclipsing binary was discovered by data-mining the TESS and ASAS-3 databases as a 9.2 d. eccentric binary with very fast apsidal motion and milimagnitude pulsations. There are three main goals for this campaign: 1) Identifying which component of this 11" visual binary is the actual eclipsing binary (that hasn't been resolved by TESS and ASAS); 2) Monitoring the eclipses to determine the apsidal motion period; 3) Identifying which of the two stars shows the observed DSCT pulsations.
Justification:
AAVSO observers able to separate objects 11" apart will be able to determine the identifications of the involved variable stars and provide long-term coverage of the eclipse changes in order to determine the apsidal motion and improve the orbital period. Milimagnitude precision will be required to detect the 0.003 mag. pulsations in one of the stars and identify it.
Requested Data Types:
Photometry
Targets
| Name | Magnitude | Variability Type | Photometry Notes | Spectroscopy Notes |
|---|---|---|---|---|
| HD 83742 | 7.17 | EA+DSCT |
Cadence: Custom Precision: 100 |
Not Requested |
| HD 302301 | 8.18 | None |
Cadence: Custom Precision: 100 |
Not Requested |
Spectroscopy Lines:
No spectroscopy lines provided
Photometry Filters:
V (Johnson), Other (Please Specify)
Comparison Stars:
Finder charts with comparison stars may be created using the AAVSO's Variable Star Plotter (VSP; https://apps.aavso.org/vsp/)
Co-Authorship
Observers are not eligible for co-authorship.
Additional Observer Input:
Please obtain observations of both HD 83742 and HD 302301, until we determine the correct identifications. Once the identification is established we will update the strategy in the campaign page.
Additional Submission Location:
Not provided
Forum URL
N/A
Notes:
Cadence will vary depending on the stage of the project. Hourly observations around the eclipse times will be enough to identify the correct variable. When the identification is established and the long-term monitoring campaign starts, continuous observations around the time of the eclipse (keep in mind that the ephemeris will have an increasing error with time due to the star behaviour) are encouraged. Dense time series with the aim of obtaining a precision close to 0.001 mag. are needed to detect the DSCT variations (P= 0.14 d.) V data are preferred but milticolor observations are welcomed. You can also submit unfiltered observations if you do not have standard filters, since the first goal of this campaign is identifying the object showing the eclipses. But do not submit them if you are not going to obtain time series or monitor the star in the long term, so your observations can be shifted to the standard V zero point. That is, a single unfiltered point is not useful. Ephemeris for the primary eclipse (August 2024 - July 2025) HJD mideclipse DD/MM/YYYY UT midecl DoW 2460526.9232 4/8/2024 10:09:24 Sunday 2460536.1146 13/8/2024 14:45:01 Tuesday 2460545.3060 22/8/2024 19:20:38 Thursday 2460554.4974 31/8/2024 23:56:15 Saturday 2460563.6888 10/9/2024 4:31:52 Tuesday 2460572.8802 19/9/2024 9:07:29 Thursday 2460582.0716 28/9/2024 13:43:06 Saturday 2460591.2630 7/10/2024 18:18:43 Monday 2460600.4544 16/10/2024 22:54:20 Wednesday 2460609.6458 26/10/2024 3:29:57 Saturday 2460618.8372 4/11/2024 8:05:34 Monday 2460628.0286 13/11/2024 12:41:11 Wednesday 2460637.2200 22/11/2024 17:16:48 Friday 2460646.4114 1/12/2024 21:52:25 Sunday 2460655.6028 11/12/2024 2:28:02 Wednesday 2460664.7942 20/12/2024 7:03:39 Friday 2460683.1770 7/1/2025 16:14:53 Tuesday 2460692.3684 16/1/2025 20:50:30 Thursday 2460701.5598 26/1/2025 1:26:07 Sunday 2460710.7512 4/2/2025 6:01:44 Tuesday 2460719.9426 13/2/2025 10:37:21 Thursday 2460729.1340 22/2/2025 15:12:58 Saturday 2460738.3254 3/3/2025 19:48:35 Monday 2460747.5168 13/3/2025 0:24:12 Thursday 2460756.7082 22/3/2025 4:59:48 Saturday 2460765.8996 31/3/2025 9:35:25 Monday 2460775.0910 9/4/2025 14:11:02 Wednesday 2460784.2824 18/4/2025 18:46:39 Friday 2460793.4738 27/4/2025 23:22:16 Sunday 2460802.6652 7/5/2025 3:57:53 Wednesday 2460811.8566 16/5/2025 8:33:30 Friday 2460821.0480 25/5/2025 13:09:07 Sunday 2460830.2394 3/6/2025 17:44:44 Tuesday 2460839.4308 12/6/2025 22:20:21 Thursday 2460848.6222 22/6/2025 2:55:58 Sunday 2460857.8136 1/7/2025 7:31:35 Tuesday 2460867.0050 10/7/2025 12:07:12 Thursday 2460876.1964 19/7/2025 16:42:49 Saturday 2460885.3878 28/7/2025 21:18:26 Monday The primary eclipse lasts 10 hours, it starts 5 hours before the published mideclipse time and ends 5 hours later. Ephemeris for the secondaryary eclipse (August 2024 - July 2025) 2460530.9022 8/8/2024 9:39:10 Thursday 2460540.0864 17/8/2024 14:04:25 Saturday 2460549.2706 26/8/2024 18:29:40 Monday 2460530.9022 8/8/2024 9:39:10 Thursday 2460540.0864 17/8/2024 14:04:25 Saturday 2460549.2706 26/8/2024 18:29:40 Monday 2460558.4548 4/9/2024 22:54:55 Wednesday 2460567.6390 14/9/2024 3:20:10 Saturday 2460576.8232 23/9/2024 7:45:24 Monday 2460586.0074 2/10/2024 12:10:39 Wednesday 2460604.3758 20/10/2024 21:01:09 Sunday 2460613.5600 30/10/2024 1:26:24 Wednesday 2460622.7442 8/11/2024 5:51:39 Friday 2460631.9284 17/11/2024 10:16:54 Sunday 2460650.2968 5/12/2024 19:07:24 Thursday 2460659.4810 14/12/2024 23:32:38 Saturday 2460668.6652 24/12/2024 3:57:53 Tuesday 2460677.8494 2/1/2025 8:23:08 Thursday 2460687.0336 11/1/2025 12:48:23 Saturday 2460696.2178 20/1/2025 17:13:38 Monday 2460705.4020 29/1/2025 21:38:53 Wednesday 2460714.5862 8/2/2025 2:04:08 Saturday 2460723.7704 17/2/2025 6:29:23 Monday 2460732.9546 26/2/2025 10:54:37 Wednesday 2460742.1388 7/3/2025 15:19:52 Friday 2460751.3230 16/3/2025 19:45:07 Sunday 2460760.5072 26/3/2025 0:10:22 Wednesday 2460769.6914 4/4/2025 4:35:37 Friday 2460778.8756 13/4/2025 9:00:52 Sunday 2460788.0598 22/4/2025 13:26:07 Tuesday 2460797.2440 1/5/2025 17:51:22 Thursday 2460806.4282 10/5/2025 22:16:36 Saturday 2460815.6124 20/5/2025 2:41:51 Tuesday 2460824.7966 29/5/2025 7:07:06 Thursday 2460833.9808 7/6/2025 11:32:21 Saturday 2460843.1650 16/6/2025 15:57:36 Monday 2460852.3492 25/6/2025 20:22:51 Wednesday 2460861.5334 5/7/2025 0:48:06 Saturday 2460870.7176 14/7/2025 5:13:21 Monday 2460879.9018 23/7/2025 9:38:36 Wednesday The secondary eclipse lasts 12 hours and 20 minutes, it starts 6 hours and 10 minutes before the published mideclipse time and ends 6 hours and 10 minutes later. Combined range recorded by surveys is V= 7.17 - 7.27. If the eclipsing binary is HD 83742 (09 38 26.33 -57 31 50.8, J2000.0), the corrected range will be V= 7.72 - 7.89 (Min II= 7.87). If the eclipsing binary is HD 302301 (09 38 25.20 -57 31 45.0, J2000.0), the corrected range will be V= 8.17 - 8.44 (Min II= 8.41).