English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We describe Spitzer IRAC and MIPS observations of the nearby 25 Myr-old opencluster NGC 2232. Combining these data with ROSAT All-Sky Survey observations,proper motions, and optical photometry/spectroscopy, we construct a list ofhighly probable cluster members. We identify 1 A-type star, HD 45435, withdefinite excess emission at 4.5--24 micron indicative of debris fromterrestrial planet formation. We also identify 2--4 late-type stars withpossible 8 micron excesses, and 8 early-type stars with definite 24 micronexcesses. Constraints on the dust luminosity and temperature suggest that thedetected excesses are produced by debris disks. From our sample of B and Astars, stellar rotation appears correlated with 24 micron excess, a resultexpected if massive primordial disks evolve into massive debris disks. Toexplore the evolution of the frequency and magnitude of debris around A-typestars, we combine our results with data for other young clusters. The frequencyof debris disks around A-type stars appears to increase from ~ 25% at 5 Myr to~ 50--60% at 20--25 Myr. Older A-type stars have smaller debris diskfrequencies: ~ 20% at 50--100 Myr. For these ages, the typical level of debrisemission rises from 5--20 Myr and then declines. Because 24 micron dustemission probes icy planet formation around A-type stars, our results suggestthat the frequency of icy planet formation is eta(i) > 0.5--0.6. Thus, mostA-type stars (approx. 1.5--3 Msun) produce icy planets.

A Spitzer Study of Debris Disks In The Young Nearby Cluster NGC 2232: Icy Planets Are Common Around ~ 1.5--3 Solar-Mass Stars