MUCHFUSS - Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS

TL;DR

The paper reports on the search for hot subdwarf stars with massive unseen companions using SDSS data, identifying candidate systems including eclipsing binaries with potential substellar companions, contributing to understanding binary evolution.

Contribution

It introduces the MUCHFUSS project and presents the identification of about 1100 hot subdwarfs, along with the discovery of nine close binary systems, including two eclipsing binaries with likely substellar companions.

Findings

Identified ~1100 hot subdwarfs from SDSS data.

Discovered nine close binary subdwarfs with short orbital periods.

Found two eclipsing binaries with probable substellar companions.

Abstract

The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions (white dwarfs with masses $M>1.0 {\rm M_{\odot}}$, neutron stars or black holes). The existence of such systems is predicted by binary evolution calculations and some candidate systems have been found. We identified $\simeq1100$ hot subdwarf stars from the Sloan Digital Sky Survey (SDSS). Stars with high velocities have been reobserved and individual SDSS spectra have been analysed. About 70 radial velocity variable subdwarfs have been selected as good candidates for follow-up time resolved spectroscopy to derive orbital parameters and photometric follow-up to search for features like eclipses in the light curves. Up to now we found nine close binary sdBs with short orbital periods ranging from $\simeq0.07 {\rm d}$ to $1.5 {\rm d}$. Two of them are eclipsing binaries with companions that are most likely of substellar nature.