NGTS clusters survey – I. Rotation in the young benchmark open cluster Blanco 1. Issue 1 (8th January 2020)

• Record Type: Journal Article
• Authors: Gillen, Edward; Briegal, Joshua T; Hodgkin, Simon T; Foreman-Mackey, Daniel; Van Leeuwen, Floor; Jackman, James A G; McCormac, James; West, Richard G; Queloz, Didier; Bayliss, Daniel; Goad, Michael R; Watson, Christopher A; Wheatley, Peter J; Belardi, Claudia; Burleigh, Matthew R; Casewell, Sarah L; Jenkins, James S; Raynard, Liam; Smith, Alexis M S; Tilbrook, Rosanna H; Vines, Jose I
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 492:Issue 1(2020)
• Page Start: 1008
• Page End: 1024
• Publication Date: 2020-01-08
• Subjects: stars: rotation -- stars: variables: general -- binaries: general -- open clusters and associations: individual: Blanco 1; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz3251
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We determine rotation periods for 127 stars in the ∼115-Myr-old Blanco 1 open cluster using ∼200 d of photometric monitoring with the Next Generation Transit Survey. These stars span F5–M3 spectral types (1.2 M⊙ ≳ M ≳ 0.3 M⊙ ) 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, generalized autocorrelation function (G-ACF), and Lomb–Scargle (LS) periodogram, and find that the GP and G-ACF methods 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 d, 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.