arXiv subjects

Amitay Sussholz

Publications and source records attributed to Amitay Sussholz.

3 recordsLinked to original sources

arXiv2026

The slower rotation of planet-hosting stars revisited

Previous studies combined rotation periods derived from Kepler photometry, stellar parameters from previous Gaia Data Releases, and planet hosts from the NASA Exoplanet Archive to conclude that statistically planet-hosting stars rotate slower than stars without detected planets. Here, we revisit these studies by using similar Kepler rotational period sample, but with an updated Gaia DR3-based stellar parameter catalogue and an updated exoplanet catalogue. We apply minimal sample cuts in evolutionary state, metallicity, and distance, and then model the stellar rotation period as a function of effective temperature alone. For each star, we derive the ratio of its observed period to the temperature-expected period, and compare the ratio distributions for the planet-host and non-host stars. For periods shorter than 20 d, the planet-host distribution of this ratio is shifted towards longer periods; the period-ratio median is ~15% larger for hosts than for non-hosts (p_KS = 2.4 x 10^-4). We also examine the recently published TESS All-Sky Rotation Survey (TARS) and find a similar trend. However, the strongly structured period distribution precludes a robust comparison between the host and the non-host stars. Therefore, the updated analysis, using more robust stellar and planetary parameters, recovers the previously reported association, strengthening the case for a genuine connection between stellar rotation and planet occurrence.

astro-ph.SR↗

arXiv2026

Revisiting Stellar equatorial rotational velocities with Gaia DR3 line broadening -- the dependence on temperature, mass and age

We used more than $10^5$ Gaia DR3 line broadening vbroad measurements to examine stellar rotation as a function of stellar temperature, mass and age. The large sample clearly displays the Kraft break at $\sim 6{,}500$\,K, or mass of $\sim1.3\,M_{\odot}$-while vbroad are small, on the order of $10$-$20$ km/s, for stars cooler than the Kraft break, they sharply rise above the break, reaching up $\sim100$ km/s with temperature of $7{,}000$ K. To follow the stellar rotation as a function of age, we consider vbroad as a function of scaled age-stellar age divided by the relevant Terminal Age Main Sequence (MS), for four narrow mass bins. We find that stellar rotation deceleration is slow during the MS phase and fast afterwards for stars hotter than the break, whereas deceleration rate is relatively high and does not vary much for the cool stars. Our findings are consistent with the theory that stellar rotation slowing is due to magnetic breaking, emanating from magnetic fields that are anchored to the stellar convective envelopes. Therefore, deceleration is high in cool stars, but in hot stars only after they leave the MS and develop convective outer layers

astro-ph.SR↗

arXiv2022

Probable Dormant Neutron Star in a Short-Period Binary System

We have identified 2XMM J125556.57+565846.4, at a distance of 600 pc, as a binary system consisting of a normal star and a probable dormant neutron star. Optical spectra exhibit a slightly evolved F-type single star, displaying periodic Doppler shifts with a 2.76-day Keplerian circular orbit, with no indication of light from a secondary component. Optical and UV photometry reveal ellipsoidal variations with half the orbital period, due to the tidal deformation of the F star. The mass of the unseen companion is constrained to the range $1.1$--$2.1\,M_{\odot}$ at $3σ$ confidence, with the median of the mass distribution at $1.4\,M_{\odot}$, the typical mass of known neutron stars. A main-sequence star cannot masquerade as the dark companion. The distribution of possible companion masses still allows for the possibility of a very massive white dwarf. The companion itself could also be a close pair consisting of a white dwarf and an M star, or two white dwarfs, although the binary evolution that would lead to such a close triple system is unlikely. Similar ambiguities regarding the certain identification of a dormant neutron star are bound to affect most future discoveries of this type of non-interacting system. If the system indeed contains a dormant neutron star, it will become, in the future, a bright X-ray source and afterwards might even host a millisecond pulsar.

astro-ph.SR↗