TY - JOUR
T1 - Long-term X-Ray Variability on the Benchmark YSO HL Tau
AU - Silverberg, Steven M.
AU - Wolk, Scott J.
AU - Principe, David A.
AU - Schneider, P. C.
AU - Günther, Hans Moritz
AU - Kim, Jinyoung Serena
AU - Kastner, Joel H.
N1 - Publisher Copyright:
© 2025. The Author(s). Published by the American Astronomical Society.
PY - 2025/3/3
Y1 - 2025/3/3
N2 - HL Tau is one of the most well-studied Class I young stellar objects (YSOs), including frequent observations at near- and mid-infrared, (sub)millimeter, and X-ray wavelengths. We present the results of an X-ray variability monitoring campaign with XMM-Newton in 2020 and X-ray grating spectroscopy from Chandra/HETGS in 2018. We find that the X-ray spectrum of HL Tau is consistently hot (with characteristic plasma temperatures T ≳ 30 MK) over 31 epochs spanning 20 yr, which is consistent in temperature with most Class I YSOs. The high-resolution HETG spectrum indicates the presence of some cooler plasma. We characterize the variability of the star across the 31 observations and find a subset of observations with significant variability on a ∼21-day timescale in the observed count rate and flux. We discuss the possible origins of this variability and identify further observations that would better constrain the nature of the changes.
AB - HL Tau is one of the most well-studied Class I young stellar objects (YSOs), including frequent observations at near- and mid-infrared, (sub)millimeter, and X-ray wavelengths. We present the results of an X-ray variability monitoring campaign with XMM-Newton in 2020 and X-ray grating spectroscopy from Chandra/HETGS in 2018. We find that the X-ray spectrum of HL Tau is consistently hot (with characteristic plasma temperatures T ≳ 30 MK) over 31 epochs spanning 20 yr, which is consistent in temperature with most Class I YSOs. The high-resolution HETG spectrum indicates the presence of some cooler plasma. We characterize the variability of the star across the 31 observations and find a subset of observations with significant variability on a ∼21-day timescale in the observed count rate and flux. We discuss the possible origins of this variability and identify further observations that would better constrain the nature of the changes.
UR - https://www.scopus.com/pages/publications/86000161459
UR - https://www.scopus.com/inward/citedby.url?scp=86000161459&partnerID=8YFLogxK
U2 - 10.3847/1538-3881/adb284
DO - 10.3847/1538-3881/adb284
M3 - Article
AN - SCOPUS:86000161459
SN - 0004-6256
VL - 169
JO - Astronomical Journal
JF - Astronomical Journal
IS - 3
M1 - 177
ER -