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The PDS 110 Observing Campaign - Photometric and Spectroscopic Observations Reveal Eclipses Are Aperiodic The PDS 110 observing campaign - photometric and spectroscopic observations reveal eclipses are aperiodic Osborn, H. P., Kenworthy, M., Rodriguez, J. E., de Mooij, E. J. W., Kennedy, G. M., Relles, H., Gomez, E., Hippke, M., Banfi, M., Barbieri, L., Becker, I. S., Benni, P., Berlind, P., Bieryla, A., Bonnoli, G., Boussier, H., Brincat, S. M., Briol, J., Burleigh, M. R., ... Zhou, G. (2019). The PDS 110 observing campaign - photometric and spectroscopic observations reveal eclipses are aperiodic. Monthly Notices of the Royal Astronomical Society, Advance Access. https://doi.org/10.1093/mnras/stz283 Published in: Monthly Notices of the Royal Astronomical Society, Advance Access Document Version: Peer reviewed version Queen's University Belfast - Research Portal: Link to publication record in Queen's University Belfast Research Portal Publisher rights © 2019 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society This work is made available online in accordance with the publisher’s policies. Please refer to any applicable terms of use of the publisher. General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policy The Research Portal is Queen's institutional repository that provides access to Queen's research output. Every effort has been made to ensure that content in the Research Portal does not infringe any person's rights, or applicable UK laws. If you discover content in the Research Portal that you believe breaches copyright or violates any law, please contact [email protected]. Download date:04. Oct. 2021 The PDS 110 observing campaign 1 The PDS 110 observing campaign { photometric and Downloaded from https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stz283/5304181 by Queen's University Belfast user on 12 February 2019 spectroscopic observations reveal eclipses are aperiodic? H.P. Osborny 1, M. Kenworthy2, J.E. Rodriguez3, E.J.W. de Mooij4, G.M. Kennedy5;6, H. Relles7, E. Gomez,7, M. Hippke8, M. Banfiz, L. Barbieriz, I.S. Becker9, P. Benniz;10, P. Berlind3, A. Bieryla3, G. Bonnoli11, H. Boussierz, S.M. Brincatz, J. Briolz, M.R. Burleigh12, T. Butterley13, M.L. Calkins3, P. Chote5, S. Ciceri14, M. Deldemz, V.S. Dhillon15;16, E. Dosez, F. Duboisz;17, S. Dvorakz, G.A. Esquerdo3, D.F. Evans18, S. Ferratfiatz, S.J. Fossey19;20, M.N. Gunther¨ 21, J. Hallz, F.-J. Hambschz;22, E. Herrero23, K. Hillsz, R. Jamesz, R. Jayawardhana24, S. Kafka25, T.L. Killesteinz;4, C. Kotnikz, D.W. Latham3, D. Lemayz, P. Lewinz, S. Littlefair15, C. Loprestiz, M. Mallonn26, L. Mancini27;28;29, A. Marchiniz;11, J.J. McCormac5;6, G. Murawskiz;30, G. Myersz 25, R. Papiniz, V. Popovz;31, U. Quadriz, S.N. Quinn3, L. Raynard12, L. Rizzutiz, J. Robertson32, F. Salvaggioz, A. Scholz33, R. Sfair9, A. M. S. Smith34, J. Southworth18, T.G. Tanz;35 S. Vanaverbekez;17, E.O. Waagen23, C.A. Watson36, R.G. West5;6, O.C. Winter9, P.J. Wheatley5;6, R.W. Wilson13, G. Zhou3 Affiliations are listed at the end of the paper. Accepted XXX. Received YYY; in original form ZZZ ABSTRACT PDS 110 is a young disk-hosting star in the Orion OB1A association. Two dimming events of similar depth and duration were seen in 2008 (WASP) and 2011 (KELT), consistent with an object in a closed periodic orbit. In this paper we present data from a ground-based observing campaign de- signed to measure the star both photometrically and spectroscopically during the time of predicted eclipse in September 2017. Despite high-quality photometry, the predicted eclipse did not occur, although coherent structure is present suggesting variable amounts of stellar flux or dust obscu- ration. We also searched for RV oscillations caused by any hypothetical companion and can rule out close binaries to 0.1 Ms. A search of Sonneberg plate archive data also enabled us to extend the photometric baseline of this star back more than 50 years, and similarly does not re-detect any deep eclipses. Taken together, they suggest that the eclipses seen in WASP and KELT photometry were due to aperiodic events. It would seem that PDS 110 undergoes stochastic dimmings that are shallower and shorter-duration than those of UX Ori variables, but may have a similar mechanism. Key words: stars:individual:PDS 110 { stars: variables: T Tauri { protoplanetary discs 1 INTRODUCTION In the process of planet formation, a circumstellar disk is ? Based on observations collected with Las Cumbres Observa- formed around a star. This circumstellar disk, and the sub- tory under program LCO2017AB-003, and the European South- sequent formation of protoplanetary cores, can be probed ern Observatory, Chile under programme 299.C-5047 and studied by direct imaging, but also through photomet- y E-mail: [email protected] ric observations of young stars. Protoplanetary cores sub- 2 H.P. Osborn et al. sequently draw matter from the circumstellar disk, poten- 2 2017 PHOTOMETRIC OBSERVATIONS tially forming a circumplanetary disk that fills a signifi- Photometric observations were taken by 11 professional ob- Downloaded from https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stz283/5304181 by Queen's University Belfast user on 12 February 2019 cant fraction of the Hill sphere of the planet (e.g. see re- servatories, with dozens more professional and amateur ob- views by Armitage 2011; Kley & Nelson 2012), which ac- servers contributing through AAVSO. These spanned 10 dif- cretes either onto the exoplanet, into exo-moons, or pos- ferent optical filters including SDSS ugriz and Cousins BVRI sibly exo-rings (Canup & Ward 2002; Magni & Coradini filters, as well as the broad band NGTS filter. The majority 2004; Ward & Canup 2010). Such objects can also be of observations began around 2457980 (2017 Aug 15) and fin- probed through either direct imaging of young planets (e.g. ished once the time of predicted eclipse had past (2458090, Vanderburg et al. 2018; Ginski et al. 2018), or through pho- or 2017 Dec 3). These are summarized in Figure1. Some ob- tometric observations as they transit their host star (e.g. servations (from NGTS and AAVSO) continued into 2018, Heising et al. 2015; Aizawa et al. 2018; Teachey et al. 2018). with a small part of that extended time frame shown in Fig- One such candidate is the young star 2MASS J14074792- ure3. 3945427 (`J1407') which underwent a complex eclipse two In the following section we briefly summarize the obser- months in duration that was interpreted as the transit vations of each contributing observatory. of a highly structured ring system filling the Hill sphere (Mamajek et al. 2012; Kenworthy & Mamajek 2015). In the case of planetary companions, transit photometry and spec- 2.1 Contributing Observatories troscopy of such a Hill sphere system provides the opportu- nity to probe both the spatial and chemical composition of 2.1.1 Las Cumbres Observatory a circumplanetary disk during planetary formation. Las Cumbres Observatory (LCOGT) is a global net- Alternatively circumstellar material can also periodi- work of robotic telescopes perfectly suited to the continu- cally eclipse young stars, allowing us to probe stochastic pro- ous, median-cadence observations required to detect long- cesses in protoplanetary disks. Many young stars have been duration dimmings of young stars. Under the proposal observed to display such "dipper" behaviour (Bouvier et al. \Characterisation of the eclipsing body orbiting young star 1999; Cody & Hillenbrand 2014; Ansdell et al. 2016, 2018, PDS 110" (LCO2017AB-003), we were granted 35 hr of time etc.), and proposed explanations includes the transit of ac- on the 0.4m network. This consists of ten identical 0.4m cretion streams (Bouvier et al. 1999), material from aster- Meade telescopes at six LCOGT observatory nodes: Sid- oid collisions (Kennedy et al. 2017), coalescing circumstellar ing Spring Observatory in Australia, Teide Observatory on dust clumps (Rodriguez et al. 2013), etc. Tenerife, McDonald Observatory in Texas, Cerro Tololo in PDS 110 (HD 290380) is a young (∼ 11 Myr old) T-Tauri Chile, SAAO in Sutherland, South Africa, and Haleakala star in the Orion OB1 Association that showed two extended Observatory in Hawai'i. These have a 2000 × 3000 SBIG (2 week) eclipses (30%) in 2008 and 2011, separated by a de- STX6303 camera with a 14-position filter wheel including lay of 808 days. An analysis by Osborn et al.(2017) of all Sloan u0g0r0i0z0, and Johnson/Cousins V and B. We primar- known photometry was consistent with an unseen compan- ily used 0.4m time to observe in Sloan g0r0i0z0. ion in a periodic orbit of 808 days with a predicted 3-week We were also assisted in these efforts by the observ- long eclipse occurring around September 2017, although ape- ing campaign \Time-Domain Observations of Young Stel- riodic UX Ori-like dimmings could not be ruled out. If peri- lar Objects (TOYS)" (STA2017AB-002, PI: Aleks Scholz), odic, the resulting ephemeris predicted two eclipses to have which contributed 10 hr of time on the 1m LCOGT network. already occurred (in 2013 and 2015) however, due to the un- This includes telescopes at McDonald Observatory, Cerro favourable placement of PDS 110 during this season, they Tololo, SAAO and Siding Spring Observatory. These have were not observed by any photometric survey. An observable a 4k × 4k Sinistro camera and 24 filter options including eclipse was predicted at HJD=2458015:5 ± 10 (1 − σ region Johnson/Cousins UBV RI and Sloan u0g0r0i0. We primarily Sept 9-30 2017) with a full-width half maximum of 7 ± 2 used the 1m time to observe PDS 110 in Johnson/Cousins days.
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