A survey for variable young stars with small telescopes – IX. Evolution of spot properties on YSOs in IC 5070

Carys Herbert, Dirk Froebrich, Siegfried Vanaverbeke, Aleks Scholz, Jochen Eislöffel, Thomas Urtly, Ivan L Walton, Klaas Wiersema, Nick J Quinn, Georg Piehler, Mario Morales Aimar, Rafael Castillo García, Tonny Vanmunster, Francisco C Soldán Alfaro, Faustino García de la Cuesta, Domenico Licchelli, Alex Escartin Perez, Esteban Fernández Mañanes, Noelia Graciá Ribes, José Luis Salto GonzálezStephen R L Futcher, Tim Nelson, Shawn Dvorak, Dawid Moździerski, Krzysztof Kotysz, Przemysław Mikołajczyk, George Fleming, Mark Phillips, Tony Vale, Franky Dubois, Heinz-Bernd Eggenstein, Michael A Heald, Pablo Lewin, Derek OKeeffe, Adam Popowicz, Krzysztof Bernacki, Andrzej Malcher, Slawomir Lasota, Jerzy Fiolka, Adam Dustor, Stephen C Percy, Pat Devine, Aashini L Patel, Matthew D Dickers, Lord Dover, Ivana I Grozdanova, James S Urquhart, Chris J R Lynch

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We present spot properties on 32 periodic young stellar objects in IC 5070. Long term, ∼5 yr, light curves in the V, R, and I-bands are obtained through the HOYS (Hunting Outbursting Young Stars) citizen science project. These are dissected into 6 months long slices, with 3 months oversampling, to measure 234 sets of amplitudes in all filters. We fit 180 of these with reliable spot solutions. Two thirds of spot solutions are cold spots, the lowest is 2150 K below the stellar temperature. One third are warm spots that are above the stellar temperature by less than ∼2000 K. Cold and warm spots have maximum surface coverage values of 40 per cent, although only 16 per cent of warm spots are above 20 per cent surface coverage as opposed to 60 per cent of the cold spots. Warm spots are most likely caused by a combination of plages and low-density accretion columns, most common on objects without inner disc excess emission in K − W2. Five small hot spot solutions have <3 per cent coverage and are 3000–5000 K above the stellar temperature. These are attributed to accretion, and four of them occur on the same object. The majority of our objects are likely to be accreting. However, we observe very few accretion hot spots as either the accretion is not stable on our time-scale or the photometry is dominated by other features. We do not identify cyclical spot behaviour on the targets. We additionally identify and discuss a number of objects that have interesting amplitudes, phase changes, or spot properties.

Original languageEnglish
Pages (from-to)4856-4878
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 1 Apr 2024


  • stars: formation
  • stars: pre-main-sequence
  • stars: rotation
  • stars: star spots
  • stars: variables: T Tauri


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