SN 2015bh: NGC 2770’s 4th supernova or a luminous blue variable on its way to a Wolf-Rayet star?

Thöne, C. C.; Postigo, A. de Ugarte; Leloudas, G.; Gall, C.; Cano, Z.; Maeda, Keiichi; Schulze, S.; Campana, S.; Wiersema, K.; Groh, J. H.; Rosa, Janie De La; Bauer, F. E.; Malesani, D.; Maund, Justyn R.; Morrell, N.; Beletsky, Y.

doi:10.1051/0004-6361/201629968

Cited by 65 publications

(109 citation statements)

References 130 publications

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“…This is especially true when we consider that the F606W image of the progenitor included Hα emission, while the more recent F555W image does not. In a preliminary report of groundbased photometry, Thoene et al (2015) also reported that SN 2009ip continued to fade, and by a few months after our HST images were taken, it was reported to be fainter than the progenitor.…”

Section: Sn 2009ip Late-time Photometrymentioning

confidence: 76%

Massive stars dying alone: the extremely remote environment of SN 2009ip

Smith

Andrews

Mauerhan

2016

Mon. Not. R. Astron. Soc.

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We present late-time Hubble Space Telescope (HST) images of the site of supernova (SN) 2009ip taken almost 3 yr after its bright 2012 luminosity peak. SN 2009ip is now slightly fainter in broad filters than the progenitor candidate detected by HST in 1999. The current source continues to be dominated by ongoing late-time circumstellar material interaction that produces strong Hα emission and a weak pseudo-continuum, as found previously for 1-2 yr after explosion. The intent of these observations was to search for evidence of recent star formation in the local (∼1 kpc; 10 arcsec) environment around SN 2009ip, in the remote outskirts of its host spiral galaxy NGC 7259. We can rule out the presence of any massive star-forming complexes like 30 Dor or the Carina nebula at the SN site or within a few kpc. If the progenitor of SN 2009ip was really a 50-80 M star as archival HST images suggested, then it is strange that there is no sign of this type of massive star formation anywhere in the vicinity. A possible explanation is that the progenitor was the product of a merger or binary mass transfer, rejuvenated after a lifetime that was much longer than 4-5 Myr, allowing its natal H II region to have faded. A smaller region like the Orion nebula would be an unresolved but easily detected point source. This is ruled out within ∼1.5 kpc around SN 2009ip, but a small H II region could be hiding in the glare of SN 2009ip itself. Later images after a few more years have passed are needed to confirm that the progenitor candidate is truly gone and to test for the possibility of a small H II region or cluster at the SN position.

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Section: Sn 2009ip Late-time Photometrymentioning

confidence: 76%

Massive stars dying alone: the extremely remote environment of SN 2009ip

Smith

Andrews

Mauerhan

2016

Mon. Not. R. Astron. Soc.

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“…More violent ejection events are observed in massive stars surrounded by low excitation nebulosities (e.g., the canonical luminous blue variable AG Carinae, Thackeray 1977, or the P-Cygni star itself). They have generally lower expansion velocities than those of V404 Cyg (e.g., P-Cyg ∼ 200 km s −1 , Smith & Hartigan 2006), but there have been reports of outflows as fast as 2000 km s −1 (see Thöne et al 2017). All these similarities led MD16 to describe this phase of the V404 Cyg outburst as the nebular phase.…”

Section: June 2015mentioning

confidence: 99%

The 1989 and 2015 outbursts of V404 Cygni: a global study of wind-related optical features

Sánchez

Muñoz-Darias

Casares

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The black hole transient V404 Cygni exhibited a bright outburst in June 2015 that was intensively followed over a wide range of wavelengths. Our team obtained high time resolution optical spectroscopy (∼ 90 s), which included a detailed coverage of the most active phase of the event. We present a database consisting of 651 optical spectra obtained during this event, that we combine with 58 spectra gathered during the fainter December 2015 sequel outburst, as well as with 57 spectra from the 1989 event. We previously reported the discovery of wind-related features (P-Cygni and broad-wing line profiles) during both 2015 outbursts. Here, we build diagnostic diagrams that enable us to study the evolution of typical emission line parameters, such as line fluxes and equivalent widths, and develop a technique to systematically detect outflow signatures. We find that these are present throughout the outburst, even at very low optical fluxes, and that both types of outflow features are observed simultaneously in some spectra, confirming the idea of a common origin. We also show that the nebular phases depict loop patterns in many diagnostic diagrams, while P-Cygni profiles are highly variable on time-scales of minutes. The comparison between the three outbursts reveals that the spectra obtained during June and December 2015 share many similarities, while those from 1989 exhibit narrower emission lines and lower wind terminal velocities. The diagnostic diagrams presented in this work have been produced using standard measurement techniques and thus may be applied to other active low-mass X-ray binaries.

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“…If the star is obscured by a significant mass of CSM, then an optically thick, Hα-emitting wind could explain the timescale of variability. Assuming a wind Thöne et al 2017). We indicate dotted lines for the F 350LP magnitudes during the "high" state and "low" state as discussed in Section 3.3.1.…”

Section: Pre-outburst "Flickering"mentioning

confidence: 99%

“…Many of these SN impostors have pre-outburst detections, which suggests their progenitor systems contain very massive stars. Given the luminosity, colours, and pre-outburst variability of these sources, several historical and recent SN impostors are thought to come from luminous blue variable (LBV) stars, includ-ing SN 1954J (Tammann & Sandage 1968), SN 1997bs (Van Dyk et al 2000, SN 2000ch (Wagner et al 2004;Pastorello et al 2010), SN 2002kg (Weis & Bomans 2005;Maund et al 2006), SN 2008S (Smith et al 2009), SN 2009ip and UGC2773-OT Foley et al 2011), SN 2015bh (also known as SNHunt 275 and PTF13efv; Ofek et al 2016;Elias-Rosa et al 2016;Thöne et al 2017), and PSN J09132750+7627410 (Tartaglia et al 2016). Light echoes from the Galactic LBV η Car indicate that many SN impostors are spectroscopically similar to the nonterminal great eruption of that star in the 1830s, which ejected a massive, bipolar nebula of circumstellar material (CSM) but left a surviving star .…”

Section: Introductionmentioning

confidence: 99%

Connecting the progenitors, pre-explosion variability and giant outbursts of luminous blue variables with Gaia16cfr

Kilpatrick

Foley

Drout

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present multi-epoch, multi-colour pre-outburst photometry and post-outburst light curves and spectra of the luminous blue variable (LBV) outburst Gaia16cfr discovered by the Gaia satellite on 1 December 2016 UT. We detect Gaia16cfr in 13 epochs of Hubble Space Telescope imaging spanning phases of 10 yr to 8 months before the outburst and in Spitzer Space Telescope imaging 13 yr before outburst. Pre-outburst optical photometry is consistent with an 18 M F8 I star, although the star was likely reddened and closer to 30 M . The preoutburst source exhibited a significant near-infrared excess consistent with a 120 AU shell with 4 × 10 −6 M of dust. We infer that the source was enshrouded by an optically-thick and compact shell of circumstellar material from an LBV wind, which formed a pseudophotosphere consistent with S Dor-like variables in their "maximum" phase. Within a year of outburst, the source was highly variable on 10-30 day timescales. The outburst light curve closely matches that of the 2012 outburst of SN 2009ip, although the observed velocities are significantly slower than in that event. In Hα, the outburst had an excess of blueshifted emission at late times centred around −1500 km s −1 , similar to that of double-peaked Type IIn supernovae and the LBV outburst SN 2015bh. From the pre-outburst and post-outburst photometry, we infer that the outburst ejecta are evolving into a dense, highly structured circumstellar environment from precursor outbursts within years of the December 2016 event.1 Although "SN impostor" implies that these objects are not genuine corecollapse SNe and thus confuses a physical mechanism with an observational class of transients, we use this label for consistency with the existing literature. This does not imply that we think a single physical mechanism powers these objects or that none of these objects is a core-collapse SN.

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SN 2015bh: NGC 2770’s 4th supernova or a luminous blue variable on its way to a Wolf-Rayet star?

Cited by 65 publications

References 130 publications

Massive stars dying alone: the extremely remote environment of SN 2009ip

Massive stars dying alone: the extremely remote environment of SN 2009ip

The 1989 and 2015 outbursts of V404 Cygni: a global study of wind-related optical features

Connecting the progenitors, pre-explosion variability and giant outbursts of luminous blue variables with Gaia16cfr

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