Rising from the Ashes: Mid-infrared Re-brightening of the Impostor SN 2010da in NGC 300

We present multi-epoch mid-infrared (IR) photometry and the optical discovery observations of the "impostor" supernova (SN) 2010da in NGC 300 using new and archival Spitzer Space Telescope images and ground-based observatories. The mid-infrared counterpart of SN 2010da was detected as Spitzer Infrared Intensive Transient Survey (SPIRITS) 14bme in the SPIRITS, an ongoing systematic search for IR transients. Before erupting on 2010 May 24, the SN 2010da progenitor exhibited a constant mid-IR flux at 3.6 and only a slight ~10% decrease at 4.5 μm between 2003 November and 2007 December. A sharp increase in the 3.6 μm flux followed by a rapid decrease measured ~150 days before and ~80 days after the initial outburst, respectively, reveal a mid-IR counterpart to the coincident optical and high luminosity X-ray outbursts. At late times, after the outburst (~2000 days), the 3.6 and 4.5 μm emission increased to over a factor of two times the progenitor flux and is currently observed (as of 2016 Feb) to be fading, but still above the progenitor flux. We attribute the re-brightening mid-IR emission to continued dust production and increasing luminosity of the surviving system associated with SN 2010da. We analyze the evolution of the dust temperature (T_d ~ 700–1000 K), mass (M_d ~ 0.5–3.8 × 10^(−7) M⊙), luminosity (L_(IR) ~ 1.3–3.5 × 10^4 L⊙), and the equilibrium temperature radius (R_(eq) ~ 6.4–12.2 au) in order to resolve the nature of SN 2010da. We address the leading interpretation of SN 2010da as an eruption from a luminous blue variable high-mass X-ray binary (HMXB) system. We propose that SN 2010da is instead a supergiant (sg)B[e]-HMXB based on similar luminosities and dust masses exhibited by two other known sgB[e]-HMXB systems. Additionally, the SN 2010da progenitor occupies a similar region on a mid-IR color–magnitude diagram (CMD) with known sgB[e] stars in the Large Magellanic Cloud. The lower limit estimated for the orbital eccentricity of the sgB[e]-HMXB (e > 0.82) from X-ray luminosity measurements is high compared to known sgHMXBs and supports the claim that SN 2010da may be associated with a newly formed HMXB system

A Systematic Study of Mid-Infrared Emission from Core-Collapse Supernovae with Spirits

The American Astronomical Society. All rights reserved.We present a systematic study of mid-infrared emission from 141 nearby supernovae (SNe) observed with Spitzer/IRAC as part of the ongoing SPIRITS survey. We detect 8 Type Ia and 36 core-collapse SNe. All Type Ia/Ibc SNe become undetectable within three years of explosion, whereas 22 ± 11% of Type II SNe continue to be detected. Five Type II SNe are detected even two decades after discovery (SN 1974E, 1979C, 1980K, 1986J, and 1993J). Warm dust luminosity, temperature, and a lower limit on mass are obtained by fitting the two IRAC bands, assuming an optically thin dust shell. We derive warm dust masses between 10-6 and 10-2 M o and dust color temperatures between 200 and 1280 K. This observed warm dust could be pre-existing or newly created, but in either case represents a lower limit to the dust mass because cooler dust may be present. We present three case studies of extreme SNe. SN 2011ja (II-P) was over-luminous ([4.5] = -15.6 mag) at 900 days post explosion with increasing hot dust mass, suggesting either an episode of dust formation or intensifying circumstellar material (CSM) interactions heating up pre-existing dust. SN 2014bi (II-P) showed a factor of 10 decrease in dust mass over one month, suggesting either dust destruction or reduced dust heating. The IR luminosity of SN 2014C (Ib) stayed constant over 800 days, possibly due to strong CSM interaction with an H-rich shell, which is rare among stripped-envelope SNe. The observations suggest that this CSM shell originated from an LBV-like eruption roughly 100 years pre-explosion. The observed diversity demonstrates the power of mid-IR observations of a large sample of SNe. © 2017

RISING FROM THE ASHES: MID-INFRARED RE-BRIGHTENING OF THE IMPOSTOR SN 2010da IN NGC 300

We present multi-epoch mid-infrared (IR) photometry and the optical discovery observations of the "impostor" supernova (SN) 2010da in NGC. 300 using new and archival Spitzer Space Telescope images and ground-based observatories. The mid-infrared counterpart of SN. 2010da was detected as Spitzer Infrared Intensive Transient Survey (SPIRITS). 14bme in the SPIRITS, an ongoing systematic search for IR transients. Before erupting on 2010 May 24, the SN. 2010da progenitor exhibited a constant mid-IR flux at 3.6 and only a slight similar to 10% decrease at 4.5 mu m between 2003 November and 2007 December. A sharp increase in the 3.6 mu m flux followed by a rapid decrease measured similar to 150 days before and similar to 80 days after the initial outburst, respectively, reveal a mid-IR counterpart to the coincident optical and high luminosity X-ray outbursts. At late times, after the outburst (similar to 2000 days), the 3.6 and 4.5 mu m emission increased to over a factor of two. times the progenitor flux and is currently observed (as of 2016 Feb) to be fading, but still above the progenitor flux. We attribute the re-brightening mid-IR emission to continued dust production and increasing luminosity of the surviving system associated with SN. 2010da. We analyze the evolution of the dust temperature (T-d similar to 700-1000 K), mass (Md similar to 0.5-3.8 x. 10(-7) M circle dot), luminosity (L-IR similar to 1.3-3.5 x 10(4) L circle dot), and the equilibrium temperature radius (R-eq similar to 6.4-12.2 au) in order to resolve the nature of SN. 2010da. We address the leading interpretation of SN. 2010da as an eruption from a luminous blue variable high-mass X-ray binary (HMXB) system. We propose that SN. 2010da is instead a supergiant (sg)B[e]-HMXB based on similar luminosities and dust masses exhibited by two other known sgB[e]-HMXB systems. Additionally, the SN. 2010da progenitor occupies a similar region on a mid-IR color-magnitude diagram (CMD) with known sgB[e] stars in the Large Magellanic Cloud. The lower limit estimated for the orbital eccentricity of the sgB[e]-HMXB (e > 0.82) from X-ray luminosity measurements is high compared to known sgHMXBs and supports the claim that SN. 2010da may be associated with a newly formed HMXB system.NASA [PIDS 1083, 40204, 61002, 80015A, 80196, 80015, 10136, 10139, 11063, 11053]; National Science Foundation Graduate Research Fellowship [DGE-1144469]; United States Air Force; STScI Director's Discretionary Research FundThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

SPIRITS: Uncovering Unusual Infrared Transients with Spitzer

We present an ongoing, five-year systematic search for extragalactic infrared transients, dubbed SPIRITS—SPitzer InfraRed Intensive Transients Survey. In the first year, using Spitzer/IRAC, we searched 190 nearby galaxies with cadence baselines of one month and six months. We discovered over 1958 variables and 43 transients. Here, we describe the survey design and highlight 14 unusual infrared transients with no optical counterparts to deep limits, which we refer to as SPRITEs (eSPecially Red Intermediate-luminosity Transient Events). SPRITEs are in the infrared luminosity gap between novae and supernovae, with [4.5] absolute magnitudes between −11 and −14 (Vega-mag) and [3.6]–[4.5] colors between 0.3 mag and 1.6 mag. The photometric evolution of SPRITEs is diverse, ranging from 7 mag yr−1. SPRITEs occur in star-forming galaxies. We present an in depth study of one of them, SPIRITS 14ajc in Messier 83, which shows shock-excited molecular hydrogen emission. This shock may have been triggered by the dynamic decay of a non-hierarchical system of massive stars that led to either the formation of a binary or a protostellar merger.The SPIRITS team acknowledges generous support from the NASA Spitzer grants for SPIRITS. M.M.K. thanks the National Science Foundation for a PIRE Grant No. 1545949 for the GROWTH project. J.J. acknowledges the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469. P.A.W. and S.M. are grateful to the South African National Research Foundation (NRF) for a research grant. R.D.G. and the MLOF group were supported, in part, by the United States Air Force. H.E.B. acknowledges support by NASA through grant GO-13935 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555