Paper

Discovery of Five Candidate Analogs for \\(\\eta\\,\\)Carinae in Nearby Galaxies

Kochanek, C S, Sonneborn, G, Adams, Scott M, Stanek, K Z, Khan, Rubab

2015

Overview

The late-stage evolution of very massive stars such as \\(\\eta\\) Carinae may be dominated by episodic mass ejections which may later lead to Type II superluminous supernova (SLSN-II; e.g., SN 2006gy). However, as long as \\(\\eta\\) Car is one of a kind, it is nearly impossible to quantitatively evaluate these possibilities. Here we announce the discovery of five objects in the nearby (\\(\\sim4-8\\) Mpc) massive star-forming galaxies M51, M83, M101 and NGC6946 that have optical through mid-IR photometric properties consistent with the hitherto unique \\(\\eta\\) Car. The Spitzer mid-IR spectral energy distributions of these \\(L_{bol}\\simeq3-8\\times10^{6} L_\\odot\\) objects rise steeply in the \\(3.6-8 \\mu\\)m bands, then turn over between \\(8\\) and \\(24 \\mu\\)m, indicating the presence of warm (\\(\\sim400-600\\) K) circumstellar dust. Their optical counterparts in HST images are \\(\\sim1.5-2\\) dex fainter than their mid-IR peaks and require the presence of \\(\\sim5-10 M_\\odot\\) of obscuring material. Our finding implies that the rate of \\(\\eta\\) Car-like events is a fraction \\(f=0.094\\) (\\(0.040 < f < 0.21\\) at \\(90\\%\\) confidence) of the core-collapse supernova (ccSN) rate. If there is only one eruption mechanism and SLSN-II are due to ccSN occurring inside these dense shells, then the ejection mechanism is likely associated with the onset of carbon burning (\\(\\sim 10^3 - 10^4\\) years) which is also consistent with the apparent ages of massive Galactic shells.

• Publisher: Cornell University Library, arXiv.org
• Subject: Collapse / Cosmic dust / Ejection / Galactic evolution / Galaxies / Massive stars / Optical counterparts (astronomy) / Optical properties / Photometry / Star & galaxy formation / Star formation / Stellar evolution