arXiv subjects

Azib Norazman

Publications and source records attributed to Azib Norazman.

3 recordsLinked to original sources

arXiv2026

Observations of Exocomets

Active small bodies in extrasolar systems, the extrasolar analogues of Solar System comets, provide insights into the orbital evolution and physical processes shaping planetary systems. Since the discovery of exocomets around $\beta$ Pictoris, these small, icy bodies have shown the potential to become key probes for understanding planetary formation and migration. This review presents an overview of current observational techniques used to detect exocomets, focusing on individual systems and large-scale searches. We discuss photometric methods that identify exocomet transits through asymmetric light curves and spectroscopic techniques revealing cometary gases via time-variable absorption lines. Despite progress, significant open questions remain regarding the physical properties, occurrence rates, and similarities between exocomets and their Solar System counterparts. This review explores future opportunities in observational exocomet research, highlighting advancements required to further our understanding of these active small bodies and their role in the context of planetary system evolution.

astro-ph.EP↗

arXiv2025

An Overview of Exocomets

We give a general overview of what the scientific community refers to as "exocomets". The general definition of exocomets, as presented in this work, is discussed and compared with Solar System comets and interstellar objects, addressing their detection around main-sequence stars as well as orbiting white dwarfs. We introduce the different types of exocomet observations, highlighting the difference between exocometary 'bodies' and exocometary 'material'. We provide a census of all exocometary system candidates detected so far, both via spectroscopy and photometry, including detections around white dwarfs.

astro-ph.EP↗

arXiv2025

A Search for Transiting Exocomets in TESS Sectors 1-26

We present a search for single photometric exocomet transits using a magnitude-limited sample of stars observed by the TESS primary mission. These events are asymmetric, with a sharp ingress and more gradual egress expected because the comet tail trails behind the coma. Our goals are to estimate the occurrence rate of exocomet transits, and given sufficient numbers comment on whether the host stars are biased towards being A/F spectral types, as suggested by a previous survey with Kepler data. We recovered the previously identified exocomet transit with TESS around $\beta$ Pic (TIC 270577175) and identified three additional main sequence systems with exocomet-like transits (TIC 280832588, TIC 73149665, and TIC 143152957). We also identified one exocomet candidate around a giant star (TIC 229790952) and one around a probable supergiant (TIC 110969638). We find a total occurrence rate of $2.64\times10^{-4}$ star$^{-1}$ year$^{-1}$, much higher than Kepler's rate of $6.7 \times 10^{-6}$ star$^{-1}$ year$^{-1}$. Some of this difference may be because our rate includes a correction for detection efficiency, where the Kepler search did not. However, with only a handful of detections in each survey, the rates are also very uncertain. In contrast to the Kepler search, we find two candidate hosts that may be G types, but the spectral types would be better supported with spectroscopic follow-up. Primarily, we conclude that exocomet-like transits are very rare at 0.1%-1% transit depth levels, and that higher precision photometry to detect and characterise shallower transits effectively is the most likely path to more detections and stronger statistical conclusions.

astro-ph.EP↗