19th Century Eruption Research Articles

Correcting the historical record for Kīlauea Volcano's 1832, 1868, and 1877 summit eruptions

Three fissure eruptions are known to have occurred along the northeastern edge of Kīlauea's summit caldera in the 19th century—in the years 1832, 1868, and 1877. Modern portrayal of these eruptions on maps and in written sources indicates that the 1832 eruption was from a fissure on the side of the Poliokeawe scarp south of Byron Ledge, the 1868 eruption was from a fissure on the southern wall of Kīlauea Iki Crater and fed a lava flow that covered the bottom of that crater, and the eruption in 1877 occurred on the floor of Keanakākoʻi Crater, as well as from a fissure of uncertain location on the east wall of the caldera below Byron Ledge. New geologic mapping and a review of historical documents and maps contradict these views. We find, instead, that: (1) the 1832 eruption discharged from a fissure on Byron Ledge (not Poliokeawe scarp), from another fissure on the southwestern wall of Kīlauea Iki Crater, and from at least one fissure along the east side of Kīlauea caldera below Byron Ledge; (2) the 1868 lava erupted through the floor of Kīlauea Iki Crater, not from a fissure in its southwestern wall; and (3) the 1877 lava erupted from Kīlauea Iki Crater's mid-wall fissure (until now believed to have opened in 1868), from the fissure previously assigned an 1832 date on Poliokeawe escarpment, and from a precisely relocated vent on the northeastern wall of the caldera. Finally, no conclusive first-hand accounts of the late 19th century eruption in Keanakākoʻi Crater were identified, leaving in doubt the often-inferred 1877 date for this event. Possible alternative dates include 1868, 1879, and 1881.

The Persistent Eruption of UGC 2773-OT: finally, a decade-long extragalactic Eta Carinae analogue

While SN impostors resemble the Great Eruption of eta Car in the sense that their spectra show narrow H lines and they have typical peak absolute magnitudes of -13 to -14 mag, most extragalactic events observed so far are quite different from eta Car in duration. Their bright phases typically last for 100~d or less, rather than persisting for several years. The transient object UGC2773-OT had a similar peak absolute magnitude to other SN impostors, but with a gradual 5-yr prediscovery rise. In the 6 yr since discovery, it has faded very slowly (0.26 mag/yr). Overall, we suggest that its decade-long eruption is so far the best known analog of eta Car's 19th century eruption. We discuss extensive spectroscopy of the ongoing eruption. The spectra show interesting changes in velocity and line shape that we discuss in detail, including an asymmetric Halpha emission line that we show is consistent with the ejection of a bipolar nebula that could be very much like the Homunculus of eta Car. Moreover, changes in the line width, line profile, blue excess emission resembling that of Type IIn supernovae, and the intensity of Halpha suggest the presence of strong circumstellar interaction in the eruption at late times. This supports the hypothesis that the extended plateau of eta Car's eruption may have been powered by shock interaction as well. One interesting difference compared to eta Car, however, is that UGC2773-OT so far does not exhibit the repeated brief spikes in luminosity that have been associated with binary periastron events.

Earth & environment: Mystery volcano pinned to the tropics: Records narrow down time and place of 19th century eruption

Science NewsVolume 186, Issue 9 p. 14-14 News Earth & environment: Mystery volcano pinned to the tropics: Records narrow down time and place of 19th century eruption Beth Mole, Beth MoleSearch for more papers by this author Beth Mole, Beth MoleSearch for more papers by this author First published: 21 October 2014 https://doi.org/10.1002/scin.2014.186009016Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume186, Issue91 November 2014Pages 14-14 RelatedInformation

A model for the 19th century eruption of Eta Carinae: CSM interaction like a scaled-down Type IIn Supernova

This paper proposes a simple model for the 19th century eruption of Eta Carinae that consists of two components: (1) a strong wind (MdotM=0.33 Msun/yr; v=200 km/s), blowing for 30 years, followed by (2) a 1e50 erg explosion in 1844. The ensuing collision between the fast ejecta and the CSM causes an increase in brightness observed at the end of 1844, followed by a sustained high-luminosity phase lasting for 10-15 years that matches the historical light curve. The emergent luminosity is powered by CSM interaction, analogous to the process in luminous Type IIn supernovae, except with 10 times lower explosion energy and at slower speeds (causing a longer duration and lower emergent luminosity). Such an explosive event provides a natural explanation for the light curve evolution, but also accounts for a number of puzzling attributes of the Homunculus nebula: (1) rough equipartition of total radiated and kinetic energy, (2) the double-shell structure of the Homunculus, (3) the apparent single age and Hubble-like flow resulting from the thin swept-up shell, (4) the complex mottled appearance of the polar lobes in HST images, arising from Raleigh-Taylor or Vishniac instabilities, (5) efficient and rapid dust formation, as seen in Type IIn supernovae, and (6) the fast (5000 km/s) material outside the Homunculus, arising from the acceleration of the forward shock upon exiting the dense CSM. In principle, the bipolar shape has already been explained in earlier studies of interacting winds, except that here the CSM interaction occurs over only 10 years, producing a thin shell with the resulting structures then frozen-in to the expanding bipolar nebula. This self-consistent picture has a number of implications for other eruptive transients, many of which may also be powered by CSM interaction.

MULTI-WAVELENGTH OBSERVATIONS OF THE ENDURING TYPE IIn SUPERNOVAE 2005ip AND 2006jd

We present an observational study of the Type IIn supernovae (SNe IIn) 2005ip and 2006jd. Broad-band UV, optical and near-IR photometry, and visual-wavelength spectroscopy of SN 2005ip complement and extend upon published observations to 6.5 years past discovery. Our observations of SN 2006jd extend from UV to mid-infrared wavelengths, and like SN 2005ip, are compared to reported X-ray measurements to understand the nature of the progenitor. Both objects display a number of similarities with the 1988Z-like subclass of SN IIn including: (i) remarkably similar early- and late-phase optical spectra, (ii) a variety of high ionization coronal lines, (iii) long-duration optical and near-IR emission and, (iv) evidence of cold and warm dust components. However, diversity is apparent including an unprecedented late-time r-band excess in SN 2006jd.The observed differences are attributed to differences between the mass-loss history of the progenitor stars. We conclude that the progenitor of SN 2006jd likely experienced a significant mass-loss event during its pre-SN evolution akin to the great 19th century eruption of \eta Carinae. Contrarily, as advocated by Smith et al. (2009), we find the circumstellar environment of SN 2005ip to be more consistent with a clumpy wind progenitor.

Light echoes reveal an unexpectedly cool η Carinae during its nineteenth-century Great Eruption

η Carinae is one of the most massive binary stars in the Milky Way. It became the second-brightest star in our sky during its mid-nineteenth-century 'Great Eruption', but then faded from view (with only naked-eye estimates of brightness). Its eruption is unique in that it exceeded the Eddington luminosity limit for ten years. Because it is only 2.3 kiloparsecs away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that during its nineteenth-century eruption, η Car ejected more than ten solar masses in an event that released ten per cent of the energy of a typical core-collapse supernova, without destroying the star. Here we report observations of light echoes of η Carinae from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210 km s(-1), in good agreement with predicted expansion speeds. The light-echo spectra correlate best with those of G2-to-G5 supergiants, which have effective temperatures of around 5,000 kelvin. In contrast to the class of extragalactic outbursts assumed to be analogues of the Great Eruption of η Carinae, the effective temperature of its outburst is significantly lower than that allowed by standard opaque wind models. This indicates that other physical mechanisms such as an energetic blast wave may have triggered and influenced the eruption.

Episodic Mass Loss and Pre-SN Circumstellar Envelopes

AbstractI discuss observational clues concerning episodic mass-loss properties of massive stars in the time before the final supernova explosion. In particular, I will focus on the mounting evidence that LBVs and related stars are candidates for supernova progenitors, even though current paradigms place them at the end of core-H burning. Namely, conditions in the immediate circumstellar environment within a few 102 AU of Type IIn supernovae require very high progenitor mass-loss rates. Those rates are so high that the only known stars that come close are LBVs during rare giant eruptions. I will highlight evidence from observations of some recent extraordinary supernovae suggesting that explosive or episodic mass loss (a.k.a. LBV eruptions like the 19th century eruption of Eta Car) occur in the 5-10 years immediately preceding the SN. Finally, I will discuss some implications for stellar evolution from these SNe, the most important of which is the observational fact that the most massive stars can indeed make it to the ends of their lives with substantial H envelopes intact, even at Solar metallicity.

SN 2006gy: Discovery of the Most Luminous Supernova Ever Recorded, Powered by the Death of an Extremely Massive Star like η Carinae

(abridged) We report our discovery and observations of the peculiar Type IIn supernova SN2006gy in NGC1260, revealing that it reached a peak magnitude of -22, making it the most luminous supernova ever recorded. It is not yet clear what powers the total radiated energy of 1e51 erg, but we argue that any mechanism -- thermal emission, circumstellar interaction, or 56Ni decay -- requires a very massive progenitor star. The circumstellar interaction hypothesis would require truly exceptional conditions around the star probably experienced an LBV eruption like the 19th century eruption of eta Carinae. Alternatively, radioactive decay of 56Ni may be a less objectionable hypothesis. That power source would imply a large Ni mass of 22 Msun, requiring that SN2006gy was a pair-instability supernova where the star's core was obliterated. SN2006gy is the first supernova for which we have good reason to suspect a pair-instability explosion. Based on a number of lines of evidence, we rule out the hypothesis that SN 2006gy was a ``Type IIa'' event. Instead, we propose that the progenitor may have been a very massive evolved object like eta Carinae that, contrary to expectations, failed to completely shed its massive hydrogen envelope before it died. Our interpretation of SN2006gy implies that the most massive stars can explode earlier than expected, during the LBV phase, preventing them from ever becoming Wolf-Rayet stars. SN2006gy also suggests that the most massive stars can create brilliant supernovae instead of dying ignominious deaths through direct collapse to a black hole.

The Structure of the Homunculus. I. Shape and Latitude Dependence from H2and [Feii] Velocity Maps of η Carinae

High resolution long-slit spectra obtained with the Phoenix spectrograph on Gemini South provide our most accurate probe of the three dimensional structure of the Homunculus around eta Car. The new near-infrared spectra dramatically confirm the double-shell structure inferred previously from thermal dust emission, resolving the nebula into a very thin outer shell seen in H2 21218, and a warmer, thicker inner layer seen in [Fe II] 16435. The thin H2 skin hints that the most important mass loss during the 19th century eruption had a very short duration of less than 5 yr. H2 emission traces the majority of the mass in the nebula, and has an average density of order 10^6.5 cm-3. This emission, in turn, yields our first definitive picture of the exact shape of the nebula, plus a distance of 2350pm50 pc and an inclination angle of 41deg (the polar axis is tilted 49deg from the plane of the sky). The distribution of the H2 emission provides the first measure of the latitude dependence of the speed, mass loss, and kinetic energy associated with eta Car's 19th century explosion. Almost 75 percent of the total mass and more than 90 percent of the kinetic energy in the ejecta were released at high latitudes. This rules out a model for the bipolar shape wherein an otherwise spherical explosion was pinched at the waist by a circumstellar torus. Also, the ejecta could not have been deflected toward polar trajectories by a companion star, since the kinetic energy of the polar ejecta is greater than the binding energy of the putative binary system. Instead, most of the mass appears to have been directed poleward by the explosion itself. [abridged]