Alert Notice 751: RU Lup and BP Tau to be observed by HST and XMM-Newton

August 3, 2021

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observation Reports: https://www.aavso.org/odysseus-iv-hst-xmm-ru-lup-bp-tau
- Young Stellar Objects: https//www.aavso.org/node/86789
Note that these forum threads are NOT ths same as for Alert Notices 741 and 748.

Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomer and by HQ. Join in the discussion or ask questions there!

 

Further to AAVSO Alert Notices 741 and 748, Dr. Frederick Walter (Stony Brook University) requests AAVSO observers' assistance in monitoring the classical T Tau stars RU Lup and BP Tau in support of observations with HST and XMM-Newton scheduled for August and September 2021.

Dr. Walter writes: "Part IV of the ODYSSEUS pre-main sequence star program starts this month. ODYSSEUS is an international collaborative campaign to understand the processes involved in the formation of low mass stars, their circumstellar disks, and their planets, via the time-variability of these systems.

"The HST will monitor the pre-main sequence stars RU Lup and BP Tau, obtaining 12 sets of ultra-violet spectra spread over roughly three rotation periods for each star. The window for RU Lup is August 10-20; the window for BP Tau is August 20 - September 12. Five of the RU Lup observations will be simultaneous with X-ray observations from XMM. Neither target will be observed simultaneously with TESS, so ground-based observations are critical if we are to place the HST and XMM observations in a long-term context.

"Thank you for your contributions to the first 3 parts of the ODYSSEUS campaign. Your participation in this campaign is a big part of its success."
 
Dr. Walter provides the following information and instructions:

1. RU Lup
Coordinates (2000.0, from VSX): R.A. 15 56 42.31  Dec. -37 49 15.5
Range (VSX): 9.8 - 12.9 V

This is a bright, highly active classical T Tauri star in the Lupus star formation region. The rotation period is about 3.7 days. The system is almost pole-on, so stochastic variability dominates over rotational modulation. The VSX catalog reports it as faint as V=12.9, but it is generally closer to its brightest level [as of August 3, 2021, it is ~10.3 V, according to the AAVSO International Database]. The TESS data from 2019 shown peak-to-peak variations of 0.8 mag.

Please try to get 1% BVRI CCD photometry (0.01 mag precision), we we can determine colors to 2% or better.

The current HST schedule is:
Date            Start (UT) End (UT)
2021
August 10   20:15:00 - 20:44:59
August 11   13:33:13 - 16:44:59  * overlap with XMM
August 12   11:56:15 - 22:16:47
August 13   10:09:45 - 16:44:59  * overlap with XMM
August 14   08:23:15 - 18:43:47
August 15   06:46:16 - 16:44:59  * overlap with XMM
August 16   04:59:46 - 15:20:18
August 17   03:13:16 - 13:33:48  * overlap with XMM
August 18   01:26:46 - 11:47:18
August 19   00:00:00 - 10:10:20  * overlap with XMM
August 19   22:03:18 - 08:23:50
August 20   20:16:48 - 06:37:20

While you should try to get data while HST and/or XMM are observing, it is also important to get as complete coverage as possible during this time period. Any observations August 9 through August 20 UT are valuable.

2. BP Tau
Coordinates (2000.0, from VSX): R.A. 04 19 15.83  Dec. +29 06 26.8
Range (VSX): 10.7 - 13.6 B
Midpoint (not mean): ~12.1 V

This is a bright, classical T Tauri star in the Taurus star formation region for you northern observers. The rotation period is about 8 days. This is not as active an accretor as RU Lup; the TESS observations 2 years ago showed quasi-sinusoidal modulation with a 0.4 mag amplitude and a period of about 4.4 days.

Please try to get 1% BVRI photometry (0.01 mag precision), we we can determine colors to 2% or better.

The current HST schedule is:
Date             Start (UT) End (UT)
2021
August 20   19:20:28 - 22:14:15
August 22   15:30:00 - 00:00:00
August 24   15:15:00 - 04:59:59
August 26   15:00:00 - 04:59:59
August 28   16:05:42 - 02:29:59
August 31   09:30:00 - 09:59:58
September 01   18:31:12 - 13:36:31
September 03   19:53:28 - 23:59:59
September 05   21:06:13 - 00:00:00
September 07   22:18:58 - 04:29:59
September 09   23:31:43 - 04:29:59
September 12   00:44:28 - 04:29:59

While you should try to get data while HST is observing, it is also important to get as complete coverage as possible during this time period. Any observations August 19 through September 12 UT are valuable.

Filter Requirements: It is important to use standard broadband filters. Concentrate on B and V, and then Rc and Ic. T Tauri stars tend to be more variable at shorter wavelengths.

Charts: Charts with comparison stars for RU Lup or BP Tau may be created using the AAVSO Variable Star Plotter (VSP).

Submit observations: Please submit observations using the name RU LUP or BP TAU to the AAVSO International Database.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using material provided by Frederick Walter.

----------------------------------------

SUBMIT OBSERVATIONS TO THE AAVSO

Information on submitting observations to the AAVSO may be found at:
 - Photometry/visual observations: https://www.aavso.org/webobs
 - Spectroscopy: https://www.aavso.org/apps/avspec/

ALERT NOTICE ARCHIVE AND SUBSCRIPTION INFORMATION

An Alert Notice archive is available at the following URL:
https://www.aavso.org/aavso-alert-notices-for-observing-campaigns-and-discoveries

Subscribing and Unsubscribing may be done at the following URL:
https://www.aavso.org/aavso-alert-notice-subscribe

-------------------------------------------------

Please support the AAVSO and its mission -- Join or donate today:
https://www.aavso.org/apps/donate/