DISCOVERY OF FIVE CANDIDATE ANALOGS FOR η CARINAE IN NEARBY GALAXIES

Journal Article · Sun Dec 20 04:00:00 EST 2015 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/815/2/L18· OSTI ID:22518657

Khan, Rubab ^[1]; Adams, Scott M.; Stanek, K. Z.; Kochanek, C. S. ^[2]; others, and

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1. NASA Goddard Space Flight Center, MC 665, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)
2. Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States)

The late-stage evolution of very massive stars such as η Carinae may be dominated by episodic mass ejections that may later lead to Type II superluminous supernova (SLSN-II; e.g., SN 2006gy). However, as long as η 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 (∼4–8 Mpc) massive star-forming galaxies M51, M83, M101, and NGC 6946 that have optical through mid-infrared (mid-IR) photometric properties consistent with the hitherto unique η Car. The Spitzer mid-IR spectral energy distributions of these L{sub bol} ≃ 3–8 × 10{sup 6} L{sub ⊙} objects rise steeply in the 3.6–8 μm bands and then turn over between 8 and 24 μm, indicating the presence of warm (∼400–600 K) circumstellar dust. Their optical counterparts in HST images are ∼1.5–2 dex fainter than their mid-IR peaks and require the presence of ∼5–10 M{sub ⊙} of obscuring material. Our finding implies that the rate of η 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 Type II superluminous supernovae are due to ccSNe occurring inside these dense shells, then the ejection mechanism is likely associated with the onset of carbon burning (∼10{sup 3}–10{sup 4} years), which is also consistent with the apparent ages of massive Galactic shells.

• OSTI ID: 22518657
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 815; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CARBON BURNING
ENERGY SPECTRA
GALAXIES
GRAVITATIONAL COLLAPSE
IMAGES
INTERMEDIATE INFRARED RADIATION
MASS TRANSFER
PHOTOMETRY
STAR CLUSTERS
STAR EVOLUTION
STELLAR WINDS
SUPERNOVAE