A survey for variable young stars with small telescopes - XI. Spot Lifetimes and Coverage Distributions

Abstract We present a homogeneous analysis of rotational variability and spot properties in young stellar objects across multiple star-forming regions observed by the Hunting Outbursting Young Stars (HOYS) project. From over 2000 candidate members, we identify 144 YSOs with robust periodic signals and well-constrained multi-band amplitudes. The sample has a median age of ∼1 Myr, effective temperatures of 3500–6500 K (masses ∼0.6–2 M⊙), 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 percent fast rotators (P < 5.5 d) and 45 percent 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 multi-band 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.

Authors

Institutions

Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2026-07-28
DOI
https://doi.org/10.1093/mnras/stag1428
Primary Topic
Astrophysics and Star Formation Studies
Type
article
Field-Weighted Citation Impact
0.00
Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

A survey for variable young stars with small telescopes - XI. Spot Lifetimes and Coverage Distributions

Sławomir Bednarz, Domenico Licchelli, D. Moździerski, Cledison Marcos da Silva et al.
Monthly Notices of the Royal Astronomical Society
Astrophysics and Star Formation Studies
article

A survey for variable young stars with small telescopes - XI. Spot Lifetimes and Coverage Distributions

Sławomir Bednarz, Domenico Licchelli, D. Moździerski, Cledison Marcos da Silva, Faustino García de la Cuesta, José Luis Salto González, Carys Herbert, Juan-Luis González-Carballo, S. Vanaverbeke, Thomas Urtly, Tonny Vanmunster, Nick Quinn, Michel Michaud, Adam Popowicz, Krzysztof Kotysz, Ivan L Walton, Franky Dubois, Krzysztof Bernacki, Mario Morales Aimar, J. Eislöffel, Aashini L Patel, G. Piehler, Tony Vale, D. Froebrich, Stephen C. Percy, P. Mikołajczyk, Y. Öǧmen, J. S. Urquhart, Amritanshu Vajpayee, Matthew D. Dickers, Ivana I. Grozdanova, Rafael Castillo García, Aleks Scholz, Matthias Kolb, Simon Francis Dawes, Gregg Ruppel, Holly Stokes-Geddes, Benjamin Womack Ryan, Kathy Griffiths, Chiara F Kawohl, Jacopo Fallai, Ari M Siqueira, George Fleming, Franz-Josef Hambsch, Tim Nelson, Geoffrey Stone, Stephen R L Futcher, Tim M Kinnear, Jordi Berenguer Amatller, Francisco C Soldán Alfaro
article en

Abstract

Abstract We present a homogeneous analysis of rotational variability and spot properties in young stellar objects across multiple star-forming regions observed by the Hunting Outbursting Young Stars (HOYS) project. From over 2000 candidate members, we identify 144 YSOs with robust periodic signals and well-constrained multi-band amplitudes. The sample has a median age of ∼1 Myr, effective temperatures of 3500–6500 K (masses ∼0.6–2 M⊙), 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 percent fast rotators (P < 5.5 d) and 45 percent 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 multi-band 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.

Monthly Notices of the Royal Astronomical Society
Silesian University of Technology (PL), Royal Astronomical Society (GB), Google (United States) (US), American Bar Association (US), Parsons (United States) (US), University of St Andrews (GB), Joint Institute for Nuclear Astrophysics (US), American Association of Variable Star Observers (US), University of Kent (GB), British Astronomical Association (GB), Nokia (Finland) (FI), Indian Navy (IN), Point University (US), Royal Society Te Apārangi (NZ), Hermitage Museum (US), Austrian Federal Railways (AT), Federal Government of Mexico (MX), National Centre for Nuclear Research (PL), Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne (DE), Astrobiology Center (JP), FuelCell Energy (United States) (US), National Observatory (BR), Astronomical Institute of the Slovak Academy of Sciences (SK), Royal Observatory in Greenwich (GB), Thüringer Landessternwarte Tautenburg (DE), Astronomical Observatory (RS), Royal Museums Greenwich (GB), Stichting tot Steun VCVGZ (NL), Bühler (United Kingdom) (GB), University of Florence (IT), University of Warsaw (PL), University of Bath (GB), Universidad de Sevilla (ES), Netherlands Institute for Radio Astronomy (NL), Acciona (Spain) (ES), KU Leuven (BE)
Openalex Percentile: Top 9%
Astrophysics and Star Formation Studies
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.