HOYS Citizen Science

Newsletter Contents

Welcome to the HOYS newsletter for June 2021. It will give a brief overview of the project and a note on our most recent paper (submitted today), as well as future plans for publications.
Thank you everyone for your continued contributions!

General Project Update

The project has now collected over 45800 images and we have stored almost 204 million brightness measurements in our database.
We are now coming to the end of our annual spring/early summer 'slump' of data supply - where most targets are near or below the horizon for most of the night. All summer targets are now visible during all of the night, even if the nights are short at the moment. Hence, please keep imaging all regions in all filters as often as you can. If you have taken a break from observing for HOYS, then please consider to restart. We are a long term project and it is vital to keep the data coming in for all fields over many years to realise our long term science goals. Of course we are already publishing proof of concept papers (see below) and analysis of interesting individual sources.
The observations with the LCO by our participants are slowly coming to an end. The project will finish at the end of July. Later this week we will submit a new application for continued LCO Global Sky Partner status. This will focus on working with school teachers on using our data for science projects in schools, collaborating with the Institute for Research in Schools and utilising the Faulkes Telescope for HOYS observations.
Cumulative HOYS data
Fig.: Cumulative number of images observed for HOYS and uploaded to our database.

New Paper submitted

Our paper on finding rotation periods of young stars in the Pelican Nebula (IC5070) field has now been submitted for publication. It is preliminary titled as: A survey for variable young stars with small telescopes: IV -Rotation Periods of YSOs in IC 5070. The abstract reads as follows:

Studying rotational variability of young stars is enabling us to investigate a multitude of properties of young star-disk systems. We utilise high cadence, multi-wavelength optical time series data from the Hunting Outbursting Young Stars citizen science project to identify periodic variables in the Pelican Nebula (IC5070). A double blind study using nine different period-finding algorithms was conducted and a sample of 59 periodic variables was identified. We find that a combination of four period finding algorithms can achieve a completeness of 85% and a contamination of 30% in identifying periods in inhomogeneous data sets. The best performing methods are periodograms that rely on fitting a sine curve. Utilising GaiaEDR3 data, we have identified an unbiased sample of 40 periodic YSOs, without using any colour or magnitude selections. The sample shows a bi-modal period distribution, a disk fraction of 50%, and its statistical properties are in agreement with other similarly aged YSOs populations. In particular, we confirm that the presence of the disk is linked to predominantly slow rotation. In our sample of periodic variables, we also find pulsating giants, an eclipsing binary, and potential YSOs in the foreground of IC5070.

When the paper is published it will be made available in full via the HOYS website.
Fig2 from paper
Figure 2 from paper: Left: Sky position of all stars (small dots) in our IC5070 field. The periodic variable YSOs are over plotted as coloured circles. The colours indicate the parallax in mas and the size of the circle is proportional to the period. Sources that are part of our final IC5070 YSO sample are surrounded by a black circle. The square field is the area investigated for periodic variables by Bhardwaj et al. (2019). Right: R-I vs. absolute I colour magnitude diagram of the HOYS data in the IC5070 field. No extinction correction has been applied to determine the absolute magnitudes. Median magnitudes along each light curve for all stars are shown. Symbol size and colours are the same as in the left panel. Several of the background giants have R-I colours outside the plot area and are not shown.

Papers and Analysis to come next

We are in the process of analysing data for the next publication. We will investigate the spot properties (size, temperature) causing the observed periodic variations of stars in IC5070. This will be written up as one of the smaller HOYS papers over the next few months. After that, we will look into the long term evolution of these spots, as part of the next general HOYS paper. Furthermore, we have started to draft a paper on the detailed investigation of three variable objects in the Sigma-Ori field and advanced our planning for publications on several individual, interesting objects.
HOYS Citizen Science
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