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NGTS clusters survey - I. Rotation in the young benchmark open cluster Blanco 1

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posted on 2020-03-11, 15:15 authored by Edward Gillen, Joshua T Briegal, Simon T Hodgkin, Daniel Foreman-Mackey, Floor Van Leeuwen, James AG Jackman, James McCormac, Richard G West, Didier Queloz, Daniel Bayliss, Michael R Goad, Christopher A Watson, Peter J Wheatley, Claudia Belardi, Matthew R Burleigh, Sarah L Casewell, James S Jenkins, Liam Raynard, Alexis MS Smith, Rosanna H Tilbrook, Jose I Vines
We determine rotation periods for 127 stars in the ~115 Myr old Blanco 1 open cluster using ~200 days of photometric monitoring with the Next Generation Transit Survey (NGTS). These stars span F5-M3 spectral types (1.2 $\gtrsim M \gtrsim$ 0.3 M$_{\odot}$) and increase the number of known rotation periods in Blanco 1 by a factor of four. We determine rotation periods using three methods: Gaussian process (GP) regression, generalised autocorrelation (G-ACF) and Lomb-Scargle (LS) periodograms, and find that GPs and G-ACF are more applicable to evolving spot modulation patterns. Between mid-F and mid-K spectral types, single stars follow a well-defined rotation sequence from ~2 to 10 days, whereas stars in photometric multiple systems typically rotate faster. This may suggest that the presence of a moderate-to-high mass ratio companion inhibits angular momentum loss mechanisms during the early pre-main sequence, and this signature has not been erased at ~100 Myr. The majority of mid-F to mid-K stars display evolving modulation patterns, whereas most M stars show stable modulation signals. This morphological change coincides with the shift from a well-defined rotation sequence (mid-F to mid-K stars) to a broad rotation period distribution (late-K and M stars). Finally, we compare our rotation results for Blanco 1 to the similarly-aged Pleiades: the single star populations in both clusters possess consistent rotation period distributions, which suggests that the angular momentum evolution of stars follows a well-defined pathway that is, at least for mid-F to mid-K stars, strongly imprinted by ~100 Myr.


This research is based on data collected under the NGTS project at the ESO La Silla Paranal Observatory. The NGTS facility is funded by a consortium of institutes consisting of the University of Warwick, the University of Leicester, Queen’s MNRAS 492, 1008–1024 (2020) Downloaded from by guest on 11 March 2020 NCS – I. Rotation in Blanco 1 1023 University Belfast, the University of Geneva, the Deutsches Zentrum fur Luft- und Raumfahrt e.V. (DLR; under the ‘Großinvestition ¨ GI-NGTS’), and the University of Cambridge, together with the UK Science and Technology Facilities Council (STFC; project reference ST/M001962/1). EG gratefully acknowledges support from the David and Claudia Harding Foundation in the form of a Winton Exoplanet Fellowship. PJW was supported by STFC consolidated grant ST/P000495/1. CAW acknowledges support by the STFC grant ST/P000312/1. This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France (DOI : 10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23(Ochsenbein, Bauer & Marcout 2000). This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France(Wenger et al. 2000). This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, https: // Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.



Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 1, February 2020

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