Collaborations

GJ 4334 is a fully convective M dwarf with 23.5 rotation period. This paper dives into the flares in spectra observed contemporaneously by Hubble in the FUV and the Apache Point Observatory in the Optical. It also compares flaring behavior to an M dwarf with similar mass, EV Lac (albeit younger and more active), which has a rotation period around 4 days. While there is overlap, despite EV Lac being the faster rotator, GJ 4334 shows an more frequent large flares. In the paper it is posed that this is likely due to more CMEs and loss of angular momentum. The frequency of its large flares is represented by the flattening of the FFD distrubtion slope (Figure 2).

My part: I conducted flare analysis such as flare identification and equivalent duration calculations using altaipony (Ilin et al. 2021), stella (Feinstein et al. 2020a,2020b), and numeric integration. I also contributed to writing the "TESS Analysis" section. We used all available TESS 2-min cadence sectors for GJ 4334, and EV Lac.

To learn more about contemporaneous Optical and FUV spetral lines observations of GJ 4884 Read Paper Here!

Using Gaia DR2 to create a color-magnitude-diagram, Jao et al. (2018) discovered a gap at around an absolute G magnitude of 10, where there is 17% less stars. This gap, called the Jao Gap, is thought to be the transition in which stars experience instabilities in their internal structure that yields rapid loss of spin and sharply reduces magnetic activity. The latter was shown in Halpha (Jao et al. 2023), while in this paper we show that a similar trend is present in Ca II H & K with an variability increase at absolute G magnitude ∼11. However, there is also a similar trend in Rossby number or the rotation period over convective turnover timescale at a lower absolute magnitude (dip around absolute G magnitude 11; Figure 1).

My part: I conducted flare removal with stella (Feinstein et al. 2020a,2020b) and rotation period estimates with starspot (Angus & Garcia Soto 2023). I also contributed to writing the "Rotation" subsection.

To learn more about the potential physics behind this gap Read Paper Here!