# On the potential of transit surveys in star clusters: Impact of correlated noise and radial velocity follow-up

## TL;DR

This paper extends a formalism to evaluate transit survey yields in star clusters, considering correlated noise and radial velocity follow-up, revealing limitations and opportunities for detecting exoplanets with small telescopes in nearby clusters.

## Contribution

It introduces new expressions for noise contributions and detection statistics, analyzing their dependence on stellar mass and survey parameters, especially in the context of correlated noise and radial velocity constraints.

## Key findings

- Correlated noise reduces detection probability for high-mass stars.
- Radial velocity follow-up limits survey effectiveness in distant clusters.
- Small-aperture surveys can detect hot Neptunes in very nearby clusters.

## Abstract

We present an extension of the formalism recently proposed by Pepper & Gaudi to evaluate the yield of transit surveys in homogeneous stellar systems, incorporating the impact of correlated noise on transit time-scales on the detectability of transits, and simultaneously incorporating the magnitude limits imposed by the need for radial velocity follow-up of transit candidates. New expressions are derived for the different contributions to the noise budget on transit time-scales and the least-squares detection statistic for box-shaped transits, and their behaviour as a function of stellar mass is re-examined. Correlated noise that is constant with apparent stellar magnitude implies a steep decrease in detection probability at the high mass end which, when considered jointly with the radial velocity requirements, can severely limit the potential of otherwise promising surveys in star clusters. However, we find that small-aperture, wide field surveys may detect hot Neptunes whose radial velocity signal can be measured with present-day instrumentation in very nearby (<100 pc) clusters.