J/MNRAS/478/5091 Variable young stars photometry (Froebrich+, 2018)
A survey for variable young stars with small telescopes:
First results from HOYS-CAPS.
Froebrich D., Campbell-White J., Scholz A., Eisloffel J., Zegmott T.,
Billington S.J., Donohoe J., Makin S.V., Hibbert R., Newport R.J.,
Pickard R., Quinn N., Rodda T., Piehler G., Shelley M., Parkinson S.,
Wiersema K., Walton I.
<Mon. Not. R. Astron. Soc., 478, 5091-5103 (2018)>
=2018MNRAS.478.5091F 2018MNRAS.478.5091F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, VRI
Keywords: stars: formation - pre-main-sequence - stars: variables: general -
T-Tauri, Herbig Ae/Be
Abstract:
Variability in young stellar objects (YSOs) is one of their primary
characteristics. Long-term, multifilter, high-cadence monitoring of
large YSO samples is the key to understand the partly unusual light
curves that many of these objects show. Here we introduce and present
the first results of the HOYS-CAPS citizen science project that aims
to perform such monitoring for nearby (d<1kpc) and young (age<10Myr)
clusters and star-forming regions, visible from the northern
hemisphere, with small telescopes. We have identified and
characterized 466 variable (413 confirmed young) stars in eight young,
nearby clusters. All sources vary by at least 0.2mag in V, have been
observed at least 15 times in V, R, and I in the same night over a
period of about 2 yr, and have a Stetson index of larger than 1. This
is one of the largest samples of variable YSOs observed over such a
time span and cadence in multiple filters. About two-thirds of our
sample are classical T-Tauri stars, while the rest are objects with
depleted or transition discs. Objects characterized as bursters show
by far the highest variability. Dippers and objects whose variability
is dominated by occultations from normal interstellar dust or dust
with larger grains (or opaque material) have smaller amplitudes. We
have established a hierarchical clustering algorithm based on the
light-curve properties that allows the identification of the YSOs with
the most unusual behaviour and to group sources with similar
properties. We discuss in detail the light curves of the unusual
objects V2492 Cyg, V350 Cep, and 2MASS J21383981+5708470.
Description:
We are describing and presenting the first results of our optical
survey of nearby clusters and star-forming regions with small
telescopes. All observations are obtained with the University of
Kent's 17 inch Beacon Observatory or as part of the HOYS-CAPS
citizen science project. In this paper, we present the analysis of
variable stars in eight target fields for which V, R, and I-band data
have been taken over a period of about 2yr.
In our data set, we have identified 466 variable stars, 413 of which
are confirmed YSOs, based on the Stetson index of their light curves.
For all objects, light-curve properties such as the asymmetry metric
and slope (alpha) in the V-I versus V colour-magnitude diagram are
determined. This sample is one of the largest samples of variable YSOs
in the northern hemisphere with multicolour observations of such a
time span and cadence, with additional archival multiwavelength data
and which is well suited for follow-up observations. We find that the
number of protostars in our sample is negligible, while about 65 per
cent of the objects are CTTSs and about 35 per cent are sources with
transition or depleted discs.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 119 466 Individual properties of all stars investigated
in the paper
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 31 A31 --- Name Source name
33- 39 A7 --- Region Region
41- 50 F10.6 deg RAdeg Right ascension (J2000)
52- 59 F8.5 deg DEdeg Declination (J2000)
61- 63 I3 --- Nvar Number of points in the lightcurve used to
determine the slope alpha in the
V vs V-I diagram
65- 69 F5.1 deg alpha Slope of a linear fit in the V vs V-I
71- 75 F5.3 mag rms rms of the datapoints from the fit
77- 81 F5.2 --- M Asymmetry index
83- 87 F5.2 --- S Stetson index
89 I1 --- G Group in the dendrogram the source is
associated with
91- 94 F4.2 mag DV Range of magnitude in V band light curve
96- 99 F4.2 mag e_V rms of the V band light curve
101-104 F4.2 mag DR Range of magnitude in R band light curve
106-109 F4.2 mag e_R rms of the R band light curve
111-114 F4.2 mag DI Range of magnitude in I band light curve
116-119 F4.2 mag e_I rms of the I band light curve
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 05-Oct-2021