SPITZER/IRAC-MIPS Survey of NGC2451A and B: Debris Disks at 50-80 million years

TL;DR

This study uses Spitzer data to analyze debris disks in the 50-80 million-year-old clusters NGC 2451 A and B, revealing a higher incidence of 24-micron excesses among solar-like stars, indicating ongoing planetesimal collisions.

Contribution

It provides one of the most comprehensive debris disk surveys in the 30-130 Myr age range, highlighting the rarity of recent large collisions among solar-mass stars.

Findings

11 of 31 solar-like stars have 24-micron excesses

Only 2 members show 8-micron excesses

Very large excesses indicating recent collisions are extremely rare

Abstract

We present a Spitzer IRAC and MIPS survey of NGC 2451 A and B, two open clusters in the 50-80 Myr age range. We complement these data with extensive ground-based photometry and spectroscopy to identify the cluster members in the Spitzer survey field. We find only two members with 8 micron excesses. The incidence of excesses at 24 microns is much higher, 11 of 31 solar-like stars and 1 of 7 early-type (A) stars. This work nearly completes the debris disk surveys with Spitzer of clusters in the 30-130 Myr range. This range is of inte rest because it is when large planetesimal collisions may have still been relatively common (as indicated by the one that led to the formation of the Moon during this period of the evolution of the Solar System). We review the full set of surveys and find that there are only three possible cases out of about 250 roughly solar-mass stars where very large excesses suggest that such collisions have occurred recently.