NGTS clusters survey - I. Rotation in the young benchmark open cluster Blanco 1
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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2020
- DOI:
- 10.1093/mnras/stz3251
- arXiv:
- arXiv:1911.09705
- Bibcode:
- 2020MNRAS.492.1008G
- Keywords:
-
- stars: rotation;
- stars: variables: general;
- binaries: general;
- open clusters and associations: individual: Blanco 1;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 19 pages, 14 figures, 2 tables, accepted for publication in MNRAS