Froebrich, Dirk,
Herbert, Carys,
Scholz, Aleks,
Ryan, Benjamin W.,
Vanaverbeke, Siegfried,
Eislöffel, Jochen,
da Silva, Cledison Marcos,
Michaud, Michel,
Griffiths, Kathy,
Siqueira, Ari M.,
and others.
Urtly, Thomas,
Alfaro, Francisco C Soldán,
Fleming, George,
Ruppel, Gregg L.,
Licchelli, Domenico,
Futcher, Stephen R. L.,
Walton, Ivan L.,
Kolb, Matthias,
Aimar, Mario Morales,
Stone, Geoffrey,
Öğmen, Yenal,
Dawes, Simon Francis,
Hambsch, Franz-Josef,
Quinn, Nick J.,
González-Carballo, Juan-Luis,
Dubois, Franky,
González, José Luis Salto,
Popowicz, Adam,
Bernacki, Krzysztof,
Bednarz, Slawomir,
Nelson, Tim,
Vale, Tony,
Vanmunster, Tonny,
Piehler, Georg,
Percy, Stephen C.,
Amatller, Jordi Berenguer,
Fallai, Jacopo,
Vajpayee, Amritanshu,
de la Cuesta, Faustino García,
García, Rafael Castillo,
Moździerski, Dawid,
Kotysz, Krzysztof,
Mikołajczyk, Przemysław J.,
Stokes-Geddes, Holly,
Dickers, Matthew D.,
Grozdanova, Ivana I.,
Kawohl, Chiara F.,
Patel, Aashini L.,
Urquhart, James S.,
and
Kinnear, Tim M.
(hide)
(2026)
A survey for variable young stars with small telescopes – XI. Spot lifetimes and coverage distributions.
Monthly Notices of the Royal Astronomical Society,
551
(1).
ISSN 0035-8711.
E-ISSN 1365-2966.
(doi:10.1093/mnras/stag1428)
(KAR id:115897)
Abstract
We present a homogeneous analysis of rotational variability and spot properties in young stellar objects (YSOs) across multiple star-forming regions observed by the HOYS (Hunting Outbursting Young Stars) project. From over 2000 candidate members, we identify 144 YSOs with robust periodic signals and well-constrained multiband amplitudes. The sample has a median age of
Myr, effective temperatures of 3500–6500 K (masses
0.6–2
), and is dominated by Class 2 objects, one third of which exhibit inner disc dust emission. The rotation period distribution is strongly bimodal, with 55 per cent fast rotators (
d) and 45 per cent slow rotators. Fast rotators are predominantly inner disc-less, whereas slow rotators include both disc-bearing and disc-free systems, indicating that disc braking alone cannot explain the observed rotational states. We derive spot properties from multiband amplitudes and find that, after correcting for observational biases, the intrinsic cold-spot coverage distribution of fast rotators is well described by an exponential function. This implies that small spot coverages are intrinsically much more common than large ones, consistent with stochastic magnetic flux emergence governing spot formation. In contrast, slow rotators show a pronounced deficit of small cold spots. After considering observational biases and alternative physical explanations, we conclude that small spots on slowly rotating YSOs have significantly shorter lifetimes. These results provide new evidence that magnetic surface structure and its evolution depend on stellar rotation, placing new empirical constraints on models of magnetic activity and angular momentum evolution in young stars.
University of Kent Author Information
Froebrich, Dirk.
Herbert, Carys.
Ryan, Benjamin W..
Stokes-Geddes, Holly.
Dickers, Matthew D..
Grozdanova, Ivana I..
Kawohl, Chiara F..
Patel, Aashini L..
Urquhart, James S..
Kinnear, Tim M..
- Depositors only (login required):
https://orcid.org/0000-0003-4734-3345
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