Northern T Tau stars campaign

Affiliation
American Association of Variable Star Observers (AAVSO)
Fri, 11/13/2020 - 03:14

AAVSO Alert Notice 725 announces an observing campaign on 13 Northern T Tau stars beginning now. Please see the Notice for details and observing instructions.

There are threads for this campaign under the following forums:

- Campaigns and Observation Reports: https://www.aavso.org/northern-t-tau-stars-campaign
- Young Stellar Objects: https//www.aavso.org/northern-t-tau-stars-campaign-01

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! HST observations are planned for these objects and the dates of those observations will be posted in this forum (they will not be announced in new Alert Notices).

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ

Affiliation
American Association of Variable Star Observers (AAVSO)
Updated HST schedule for Northern T Tau stars (AN 725)

Below is a status report provided by Dr. Walter on the 13 Northern T Tau stars in this campaign. Please note the HST times as well as the Notes that follow the table.

Thank you for your observations to date! Please remember that all of the targets, including those already observed by HST, need a few observations throughout the TESS window (see the Alert Notice for full instructions).

Many thanks, and good observing,
Elizabeth

updated: 3 December 2020; 7 December 2020

Table 1: Scheduled Northern Targets

Target Alt name RA (2000) Dec (2000) meanV orbits HST times (UT)
V510 Ori   05 39 39.83 -02 31 21.9 14.3 2 Dec 07 12:34 - 15:04
          1 Dec 07 15:45 - 16:52
          2 Dec 08 12:24 - 14:54
V499 Ori CVSO-146 05 35 46.00 -00 57 52.2 14.0 1 Dec 09 20:10 - 21:17
          3 Dec 10 12:03 - 16:09
CVSO-165   05 39 02.57 -01 20 32.4 13.7 2 Dec 14 11:28 - 13:54
          2 Dec 14 14:38 - 17:04
          1 Dec 14 19:28 - 20:32
CVSO-90   05 31 20.63 -00 49 19.8 14.6 2 Dec 16 11:07 - 13:33
          1 Dec 16 14:22 - 15:21

HST observations completed

Target Alt name RA (2000) Dec (2000) meanV orbits HST times (UT)
NSV 2091 CVSO-104 05 32 06.38 -01 11 00.1 14.2 3 Nov 26 13:13 - 18:10
          1 Nov 27 04:51 - 05:55
V462 Ori CVSO-109 05 32 32.65 -01 13 45.8 14.0 2 Nov 28 01:26 - 03:54
          1 Nov 28 04:41 - 05:51
V609 Ori CVSO-176 05 40 24.15 -00 31 21.4 15.6 2 Nov 28 20:32 - 22:58
          2 Nov 29 02:53 - 05:17
          1 Nov 29 20:25 - 21:23
TX Ori   05 38 33.69 -02 44 14.1 12.1 3 Nov 30 12:10 - 16:16
          1 Dec 01 00:53 - 02:01
V505 Ori   05 38 27.26 -02 45 09.7 14.2 3 Nov 30 20:07 - 00:13 Dec 01
          1 Dec 01 02:28 - 03:36
CVSO-58   05 29 23.26 -01 25 15.5 14.9 3 Dec 01 11:59 - 16:05
          2 Dec 01 19:20 - 22:27
          1 Dec 01 23:07 - 00:14 Dec 02
CVSO-36   05 25 50.37 +01 49 37.1 16.1 3 Dec 03 11:40 - 15:45
          1 Dec 03 16:25 - 17:31
CVSO-107   05 32 25.78 -00 36 53.4 14.8 1 Dec 04 11:29 - 14:00
          2 Dec 04 14:40 - 17:10
          1 Dec 05 00:11 - 01:19
CVSO-17   05 23 04.70 +01 37 14.9 16.2 3 Dec 05 12:54 - 17:00
          1 Dec 05 20:51 - 21:57
          3 Dec 05 22:26 - 02:31 Dec 06

Not yet scheduled with HST

Target Alt name RA (2000) Dec (2000) meanV orbits HST times (UT)
all targets have been schedued            

Notes

Western hemisphere observers are encouraged to observed these targets as follows:

TX Ori Nov 29: anytime, Dec 01 0:53 - 2:01 UT (Nov 30 civil). Dec 01: anytime.

V505 Ori Nov 29: anytime. Nov 30 20:07 - 00:13 and Dec 01 2:28 - 3:36 UT (Nov 30 civil). Dec 01: anytime.

CVSO-58 Nov 30: anytime. Dec 01 23:07 - Dec 02 0:14 UT (Dec 01 civil). Dec 02 anytime.

CVSO-36 Dec 02: anytime. Dec 03: anytime, Dec 04: anytime.

CVSO-107 Dec 03: anytime. Dec 05: 00:11-01:19 UT (Dec 04 civil). Dec 05 anytime.

CVSO-17 Dec 04: anytime. Dec 05: 23:00 - Dec 06 02:31 UT (Dec 05 civil). Dec 06: anytime.

V510 Ori Dec 06: anytime. Dec 07: anytime, Dec 08: anytime, Dec 09: anytime. CVSO-146 Dec 08: anytime. Dec 09: anytime, Dec 10: anytime.
Notes:

  • In the above, a date without a UT attached refers to the civil date at the start of the night for an observer in the western hemisphere.

  • The first few scheduled minutes of each observation are used for target acquisition, so it is better to start a few minutes after the start of the HST observations than right at the stated start time.

    Remember also to obtain occasional images of all targets between Nov 19 and Dec 17, simultaneously with the TESS observations, to monitor the longer-duration color varia- tions. TESS will obtain broadband red (600-1000 nm) colors on a 10 minute cadence.

Affiliation
American Association of Variable Star Observers (AAVSO)
Summary and Thank You from Dr. Walter

This campaign on Northern T Tau stars is now concluded. Dr. Fred Walter, the Principal Investigator of this campaign, sends the following summary report and a thank you to the AAVSO:

Report on AAVSO Alert Notice 725: Campaign on Northern T Tauri Stars

F.M. Walter (Stony Brook University)

1. INTRODUCTION

On 12 November 2012 we issued Alert Notice 725, requesting photometric obser- vations in support of an HST program to obtain UV spectra of a sample of T Tauri stars in the Orion OB1b star forming region. The HST observations were planned to occur while the TESS spacecraft was imaging these regions.

The aim of the ground-based program is to obtain supporting optical and near- IR photometry and spectroscopy. TESS will return light curves with a 10 minute cadence nearly continuously for 27 days. The ground-based photometry will not be able to beat this, either for cadence or S/N, but will yield colors that will be indispensable for interpreting the TESS light curves (TESS operates in a single band, from approximately 600 to 1000 nm). We can also use calibrated R and I data from the ground to “calibrate” the TESS instrumental magnitudes.

The plan was to obtain good photometric coverage around the time of the HST observations, and to sample the light curves at other times during the TESS observa- tions. To supplement the Alert Notice, I requested observations from the AAVSOnet robotic telescopes during this time. We have also arranged for photometric coverage from HOYS, and from the Konkoly and Universita di Catania and other observatories in Europe.

Since the HST is scheduled without regard to ground-based considerations, and a given target is typically observable for about 1/3 of the night, the hope was that by getting many eyes on the targets we would obtain both simultaneity and a good record of the photometric behavior leading up to the time of the HST observations. This is important because the T Tauri stars vary irregularly for many reasons, in- cluding variable obscuration by circumstellar dust, brightening by accretion events, and magnetic flaring.

2. DATA AND RESULTS

It seems that the program has been successful. I thank the eleven observers (listed below) who have submitted data to the AAVSO (as of December 29). A summary of the number of observations made from November 6 through December 26 is given ’in Table 1 (the campaign formally ran 19 November through 17 December 2020). Unfortunately winter weather largely precluded getting observations simultaneously with the HST, at least from the western hemisphere.

Table 1. Observation summary

Target Target (Alt name) AAVSO Observer Observations AAVSOnet Observations
CVSO 17   36 39
CVSO 36   61 23
CVSO 58   89 35
CVSO 90   61 70
NSV 2091 CVSO 104 81 66
CVSO 107   71 35
V462 Ori CVSO 109 82 66
V499 Ori CVSO 146 65 11
CVSO 165   77 6
V609 Ori CVSO 176 31 10
TX Ori   595 44
V505 Ori   413 44
V510 Ori   422 37

A summary of methods and results, including some figures, is posted at http://www.astro.sunysb.edu/fwalter/SMARTS/Odysseus/.

The HST data were obtained successfully. The TESS data should be on the ground and being processed. Analysis is proceeding on this and other ground-based data. Complete results will eventually be forthcoming.

ACKNOWLEDGEMENTS

I thank the AAVSO and their crew of volunteers and observers. We should all be grateful for their dedication to variable star science, and for filling in this niche which professional astronomers have largely abdicated. I thank Elizabeth Waagen for working with me on the AAVSO Alert Notice. Mostly I wish thank the eleven of you (BSEC DSN HBB HMB KSLA MGW OAAA PDM PJAD RZD SDM) who submitted observations to the AAVSO. It take a lot of observations to construct complete light curves of irregularly-variable stars, and your data will prove invaluable.

Affiliation
American Association of Variable Star Observers (AAVSO)
Northern T Tauri Sar Campaign addendum

I'd like to again thank all of you who contributed to a very successful ground based photometric campaign.

But it's not over. For reasons I do not yet know, the HST observations of V510 Ori will be repeated Feb 12-13.

Because we will not have the TESS photometry, it is more important to have ground-based photometry this time around. So I'm asking any observers who can observe V510 Ori to do so now through the night of 14 February. Single snapshots each night will reveal long-trends in the variations. During the December campaign, which was very successful from a ground-based perspective,  V510 Ori appeared to have a 25 day periodic modulation with an amplitude of about 0.6 mag. But during the HST observations it brightened by 0.5 mag in the 24 hours as it recovered from what seemed to be a sharp dust dip (see http://www.astro.sunysb.edu/fwalter/SMARTS/Odysseus/v510ori.phot.html ).

I request BVRI CCD photometry. Orion is an early-evening target in February, so we'll need observers who are geographically-dispersed to ensure good coverage. Nightly snapshots suffice to establish the long-term trends; denser time coverage Feb 12-13 (exact times to be forthcoming) will help interpret the UV spectra.

UPDATED HST observing times:

The HST observations are scheduled from 0603-1328 UT on Feb 12 (the evening of Feb 11 for observers in the western hemisphere).

Unfortunately, this is best for observers in the mid-Pacific (anybody in Hawaii?). Observers in the southwestern US may be able to obtain simultaneous photometry in the hour or so before starset. Please obtain approximately nightly BVRI photometry through Feb 14, with a higher density of observations (if possible) on  Feb 12 UT.

Thanks,

Fred

Affiliation
American Association of Variable Star Observers (AAVSO)
V510 Ori to be re-observed by HST 2021 Feb 12 UT

AAVSO Alert Notice 728 reports on the scheduled re-observation by HST of V510 Ori, one of the targets in Dr. Walter's Northern T Tau campaign. Please see the notice for details and observing instructions.

There are threads for this campaign under the following forums:
- Campaigns and Observation Reports: https://www.aavso.org/northern-t-tau-stars-campaign
- Young Stellar Objects: https//www.aavso.org/northern-t-tau-stars-campaign-01
Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomers and by HQ. Join in the discussion or ask questions there!

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ