Â鶹ÒùÔº

Using various ground-based and space telescopes, an international team of astronomers has observed a highly variable young star known as DR Tauri. Results of the observational campaign, May 12 on the arXiv preprint server, provide crucial information regarding the short- and long-term variability of this star.

Classical T Tauri stars (CTTSs) are newly-formed, low-mass stars surrounded by protoplanetary disks. They are characterized by the presence of strong emission lines and large variations in brightness, which may be both periodic and random.

DR Tauri is a CTTS located in the Taurus star-forming region, some 610 light years away. The star has a spectral type of K5 to M0, a radius of 1.46 solar radii, and its effective temperature is estimated to be 4,100 K.

DR Tauri has been monitored for decades, and previous observations have found that it showcases irregular light variations on multiple timescales. For instance, it displays quasi-periodic signals in the range of 2−10 days, or its strong emission lines, such as the hydrogen Balmer lines, show significant variations.

In order to get more insights into the variability of DR Tauri, a group of astronomers, led by Gabriella Zsidi of the Konkoly Observatory in Budapest, Hungary, decided to make multi-filter ground-based optical, near-infrared, and space-based mid-infrared observations of this star.

The observations, which employed space telescopes such as Kepler and the Transiting Exoplanet Survey Satellite (TESS), confirmed that DR Tauri is highly variable on all timescales that are available in the obtained dataset. It turned out that the light curves of DR Tauri are primarily dominated by stochastic changes, and the typical timescale of the variability is around 2–3 days.

Furthermore, ground-based multifilter photometric observations revealed that the shape of the light curves of DR Tauri is similar in all filters, but the amplitude of the variations decreases with increasing wavelength.

"This does not closely follow the extinction curve, and the trend at the longest (mid-IR) wavelengths suggest that the inner part of the disk might be optically thick and invariable," the astronomers concluded.

However, the period analysis conducted by the team did not lead to a reliable rotational period of DR Tauri. Despite this, the researchers noted that the wavelet analysis hints at a periodic signal of around three days.

The study also found that the hydrogen-alpha line of the star exhibits the most complex and asymmetric line profile, and the variance profiles suggest that the two emission peaks show the highest variability. This, according to the scientists, indicates the presence and variation of both accretion flow and wind.

The authors of the paper conclude that the short- and long-term variability of DR Tauri is most likely caused by the combination of accretion, wind, stellar activity, and obscuration by circumstellar matter.

© 2025 Science X Network