A revised historical light curve of Eta Carinae and the timing of close periastron encounters

Smith, Nathan; Frew, David J.

doi:10.1111/j.1365-2966.2011.18993.x

Cited by 108 publications

(198 citation statements)

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“…The great eruptions in Eta Carina (but also of V838 Mon) appears to have occurred near the pericenter of the current binary system (Damineli 1996;Smith & Frew 2011). As we will discuss in § 5 this is consistent with the model we discuss here.…”

Section: Introductionsupporting

confidence: 85%

Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

Zwart

Heuvel

2016

Mon. Not. R. Astron. Soc.

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We discuss the events that led to the giant eruption of Eta Carinae, and find that the mid-nineteenth century (in 1838-1843) giant mass-loss outburst has the characteristics of being produced by the merger event of a massive close binary, triggered by the gravitational interaction with a massive third companion star, which is the current binary companion in the Eta Carinae system. We come to this conclusion by a combination of theoretical arguments supported by computer simulations using the Astrophysical Multipurpose Software Environment. According to this model the ∼ 90 M present primary star of the highly eccentric Eta Carinae binary system is the product of this merger, and its ∼ 30 M companion originally was the third star in the system.In our model the Homunculus nebula was produced by an extremely enhanced stellar wind, energized by tidal energy dissipation prior to the merger, which enormously boosted the radiation-driven wind mass-loss. The current orbital plane is then aligned with the equatorial plane of the Homunculus, and the symmetric lobes are roughly aligned with the argument of periastron of the current Eta Carina binary. The merger itself then occurred in 1838, which resulted in a massive asymmetric outflow in the equatorial plane of the Homunculus. The 1843 outburst can in our model be attributed to the subsequent encounter when the companion star (once the outer most star in the triple system) plunges through the bloated envelope of the merger product, once when it passed periastron again. We predict that the system has an excess space velocity of order 50 km/s in the equatorial plane of the Homunculus. Our triple model gives a viable explanation for the high runaway velocities typically observed in LBVs (Smith & Tombleson 2015).

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Section: Introductionsupporting

confidence: 85%

Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

Zwart

Heuvel

2016

Mon. Not. R. Astron. Soc.

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“…Producing significant levels of Thomson scattering on these large scales requires a very dense wind, similar to that of an LBV in eruption (Kochanek 2011a). We can then estimate the Hα luminosity assuming it is due to recombination outside radius R in (and ignoring R out ) as (Smith et al 2007), 1998S (Liu et al 2000), and 1994W (Sollerman et al 1998) and the SN impostor light curves of SN 2009ip (Smith et al 2010b), SN 2008S (Smith et al 2009), SN 1997bs (Van Dyk et al 2000, and the 1843 outburst of η Car (Smith & Frew 2011). Left: a comparison of the absolute magnitude assuming distance moduli for SNe 2011ht, 2006gy, 1998S, 1994W, 2009ip, 2008S, 1997bs, and η-Car of 31.42, 34.42, 31.15, 32.02, 31.55, 28.74, 30.28, and 11.81, and an E(B − V ) of 0.062, 0.76, 0.15 (Lentz et al 2001), 0.17, 0.019, 0.64, 0.21, and A V = 1.7 (Davidson & Humphreys 1997), respectively.…”

Section: Discussionmentioning

confidence: 99%

THE UNUSUAL TEMPORAL AND SPECTRAL EVOLUTION OF THE TYPE IIn SUPERNOVA 2011ht

Roming¹,

Pritchard²,

Prieto³

et al. 2012

ApJ

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We present very early UV to optical photometric and spectroscopic observations of the peculiar Type IIn supernova (SN) 2011ht in UGC 5460. The UV observations of the rise to peak are only the second ever recorded for a Type IIn SN and are by far the most complete. The SN, first classified as an SN impostor, slowly rose to a peak of M V ∼ −17 in ∼55 days. In contrast to the ∼2 mag increase in the v-band light curve from the first observation until peak, the UV flux increased by >7 mag. The optical spectra are dominated by strong, Balmer emission with narrow peaks (FWHM ∼ 600 km s −1 ), very broad asymmetric wings (FWHM ∼ 4200 km s −1 ), and blueshifted absorption (∼300 km s −1 ) superposed on a strong blue continuum. The UV spectra are dominated by Fe ii, Mg ii, Si ii, and Si iii absorption lines broadened by ∼1500 km s −1 . Merged X-ray observations reveal a L 0.2-10 = (1.0 ± 0.2) × 10 39 erg s −1 . Some properties of SN 2011ht are similar to SN impostors, while others are comparable to Type IIn SNe. Early spectra showed features typical of luminous blue variables at maximum and during giant eruptions. However, the broad emission profiles coupled with the strong UV flux have not been observed in previous SN impostors. The absolute magnitude and energetics (∼2.5 × 10 49 erg in the first 112 days) are reminiscent of normal Type IIn SN, but the spectra are of a dense wind. We suggest that the mechanism for creating this unusual profile could be a shock interacting with a shell of material that was ejected a year before the discovery of the SN.

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“…In the optical band, the brightness of η Car increased by several magnitudes during the last ∼30 years (see Fernández-Lajús et al 2009;Gomez et al 2010;Smith & Frew 2011). This increasing optical brightness suggests that the inner envelope, that enshrouds the central star, is currently opening up (Martin et al 2006), and a larger fraction of the stellar optical and UV radiation, that was previously absorbed within the nebula and thus heated the dust, is now able to leave the system.…”

Section: The Far-infrared Spectral Energy Distribution Of η Carinaementioning

confidence: 97%

“…In the optical, it once represented the second brightest star on the sky, A67, page 13 of 18 but faded by more than eight magnitudes between 1850 and 1880. During the last three decades, it brightened by several magnitudes (Martin et al 2006;Smith & Frew 2011). Strong X-ray variability is seen as a result of dynamical changes in the wind collision zone (Corcoran et al 2010).…”

Section: The Far-infrared Spectral Energy Distribution Of η Carinaementioning

confidence: 99%

Herschelfar-infrared observations of the Carina Nebula complex

Gaczkowski

Preibisch

Ratzka

et al. 2012

A&A

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Context. The Carina Nebula represents one of the largest and most active star forming regions known in our Galaxy. It contains numerous very massive (M > ∼ 40 M ) stars that strongly affect the surrounding clouds by their ionizing radiation and stellar winds. Aims. Our recently obtained Herschel PACS and SPIRE far-infrared maps cover the full area (≈8.7 deg 2 ) of the Carina Nebula complex (CNC) and reveal the population of deeply embedded young stellar objects (YSOs), most of which are not yet visible in the mid-or near-infrared. Methods. We study the properties of the 642 objects that are independently detected as point-like sources in at least two of the five Herschel bands. For those objects that can be identified with apparently single Spitzer counterparts, we use radiative transfer models to derive information about the basic stellar and circumstellar parameters. Results. We find that about 75% of the Herschel-detected YSOs are Class 0 protostars. The luminosities of the Herschel-detected YSOs with SED fits are restricted to values of ≤5400 L , their masses (estimated from the radiative transfer modeling) range from ≈1 M to ≈10 M . Taking the observational limits into account and extrapolating the observed number of Herschel-detected protostars over the stellar initial mass function suggest that the star formation rate of the CNC is ∼0.017 M /year. The spatial distribution of the Herschel YSO candidates is highly inhomogeneous and does not follow the distribution of cloud mass. Rather, most Herschel YSO candidates are found at the irradiated edges of clouds and pillars. The far-infrared fluxes of the famous object η Car are about a factor of two lower than expected from observations with the Infrared Space Observatory obtained 15 years ago; this difference may be a consequence of dynamical changes in the circumstellar dust in the Homunculus Nebula around η Car. Conclusions. The currently ongoing star formation process forms only low-mass and intermediate-mass stars, but no massive (M > ∼ 20 M ) stars. The characteristic spatial configuration of the YSOs provides support to the picture that the formation of this latest stellar generation is triggered by the advancing ionization fronts.

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A revised historical light curve of Eta Carinae and the timing of close periastron encounters

Cited by 108 publications

References 78 publications

Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

THE UNUSUAL TEMPORAL AND SPECTRAL EVOLUTION OF THE TYPE IIn SUPERNOVA 2011ht

Herschelfar-infrared observations of the Carina Nebula complex

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