Modelling the Central Constant Emission X-ray component of η Carinae

Russell, Christopher M. P.; Corcoran, M. F.; Hamaguchi, Kenji; Madura, Thomas; Owocki, S. P.; Hillier, D. J.

doi:10.1093/mnras/stw339

Cited by 19 publications

(14 citation statements)

References 45 publications

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“…Numerical simulations of the wind-wind collision in a region centered on η Car and extending up to 100 times the semi-major axis of the binary orbit show a series of dense (n e ∼ 10 7 cm −3 ) arc-like features formed by both the colliding winds and the winds ejected in the previous cycles (Parkin, et al 2011;Clementel et al 2014;Russell et al 2016) that are in good agreement with observed optical images (Gull et al 2016).…”

Section: Introductionsupporting

confidence: 76%

$η$ Carinae: high angular resolution continuum, H30$α$ and He30$α$ ALMA images

Abraham,

Beaklini,

Cox

et al. 2020

Preprint

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We present images of η Carinae in the recombination lines H30α and He30α and the underlying continuum with 50 mas resolution (110 AU), obtained with ALMA. For the first time, the 230 GHz continuum image is resolved into a compact core, coincident with the binary system position, and a weaker extended structure to the NW of the compact source. Iso-velocity images of the H30α recombination line show at least 16 unresolved sources with velocities between -30 and -65 km s −1 distributed within the continuum source. A NLTE model, with density and temperature of the order 10 7 cm −3 and 10 4 K, reproduce both the observed H30α line profiles and their underlying continuum flux densities. Three of these sources are identified with Weigelt blobs D, C and B; estimating their proper motions, we derive ejection times (in years) of 1952.6, 1957.1, and 1967.6, respectively, all of which are close to periastron passage. Weaker H30α line emission is detected at higher positive and negative velocities, extending in the direction of the Homunculus axis. The He30α recombination line is also detected with the same velocity of the narrow H30α line. Finally, the close resemblance of the H30α image with that of an emission line that was reported in the literature as HCO + (4-3) led us to identify this line as H40δ instead, an identification that is further supported by modeling results. Future observations will enable to determine the proper motions of all the compact sources discovered in the new high-angular resolution data of η Carinae.

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Section: Introductionsupporting

confidence: 76%

$η$ Carinae: high angular resolution continuum, H30$α$ and He30$α$ ALMA images

Abraham,

Beaklini,

Cox

et al. 2020

Preprint

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“…However, there is also faster material in the system. Hard X-ray emission from the colliding-wind binary suggests that a companion star has a very fast wind of 2000-3000 km s −1 (Corcoran et al 2001;Pittard & Corcoran 2002;Parkin et al 2011;Russell et al 2016). In spectra of the central star system, speeds as fast as −2000 km s −1 are only seen in absorption at certain phases, attributed to the companion's wind shocking the primary star's wind along our line of sight (Groh et al 2010).…”

Section: Introductionmentioning

confidence: 89%

Exceptionally fast ejecta seen in light echoes of Eta Carinae’s Great Eruption

Smith

Rest

Andrews

et al. 2018

Monthly Notices of the Royal Astronomical Society

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In our ongoing study of η Carinae's light echoes, there is a relatively bright echo that has been fading slowly, reflecting the 1845-1858 plateau phase of the eruption. A separate paper discusses its detailed evolution, but here we highlight one important result: the Hα line in this echo shows extremely broad emission wings that reach −10,000 km s −1 to the blue and +20,000 km s −1 to the red. The line profile shape is inconsistent with electron scattering wings, so the broad wings indicate high-velocity outflowing material. To our knowledge, these are the fastest outflow speeds ever seen in a non-terminal massive star eruption. The broad wings are absent in early phases of the eruption in the 1840s, but strengthen in the 1850s. These speeds are two orders of magnitude faster than the escape speed from a warm supergiant, and 5-10 times faster than winds from O-type or Wolf-Rayet stars. Instead, they are reminiscent of fast supernova ejecta or outflows from accreting compact objects, profoundly impacting our understanding of η Car and related transients. This echo views η Car from latitudes near the equator, so the high speed does not trace a collimated polar jet aligned with the Homunculus. Combined with fast material in the Outer Ejecta, it indicates a wide-angle explosive outflow. The fast material may constitute a small fraction of the total outflowing mass, most of which expands at ∼600 km s −1 . This is reminiscent of fast material revealed by broad absorption during the presupernova eruptions of SN 2009ip.

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“…In particular, estimates of the companion's wind indicate extreme physical parameters. Typical values for the mass-loss rate and wind speed of η Car's companion derived by comparing models of the colliding winds with observed X-ray emis-sion are Ṁ =(1-2)×10 −5 M⊙ yr −1 and v∞≈3000 km s −1 , respectively (Parkin et al 2011(Parkin et al , 2009Corcoran et al 2010;Corcoran 2005;Pittard & Corcoran 2002;Okazaki et al 2008;Russell et al 2016;Hamaguchi et al 2016). This is a much denser and faster wind than any normal main-sequence O-type star, especially when considering constraints on the companion's luminosity and ionizing flux that would point to an initially ∼30 M⊙ star or less (Mehner et al 2010;Teodoro et al 2008;Verner et al 2005).…”

Section: But What About the Weird Surviving Companion?mentioning

confidence: 99%

Light echoes from the plateau in Eta Carinae’s Great Eruption reveal a two-stage shock-powered event

Smith

Andrews

Rest

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present multi-epoch photometry and spectroscopy of a light echo from η Carinae’s 19th century Great Eruption. This echo's light curve shows a steady decline over a decade, sampling the 1850s plateau of the eruption. Spectra show the bulk outflow speed increasing from ∼150 km s−1 at early times, up to ∼600 km s−1 in the plateau. Later phases also develop remarkably broad emission wings indicating mass accelerated to more than 10 000 km s−1. Together with other clues, this provides direct evidence for an explosive ejection. This is accompanied by a transition from a narrow absorption line spectrum to emission lines, often with broad or asymmetric P Cygni profiles. These changes imply that the pre-1845 luminosity spikes are distinct from the 1850s plateau. The key reason for this change may be that shock interaction with circumstellar material (CSM) dominates the plateau. The spectral evolution of η Car closely resembles that of the decade-long eruption of UGC 2773-OT, which had clear signatures of shock interaction. We propose a two-stage scenario for η Car’s eruption: (1) a slow outflow in the decades before the eruption, probably driven by binary interaction that produced a dense equatorial outflow, followed by (2) explosive energy injection that drove CSM interaction, powering the plateau and sweeping slower CSM into a fast shell that became the Homunculus. We discuss how this sequence could arise from a stellar merger in a triple system, leaving behind the eccentric binary seen today. This gives a self-consistent scenario that may explain interacting transients across a wide range of initial mass.

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Modelling the Central Constant Emission X-ray component of η Carinae

Cited by 19 publications

References 45 publications

$η$ Carinae: high angular resolution continuum, H30$α$ and He30$α$ ALMA images

$η$ Carinae: high angular resolution continuum, H30$α$ and He30$α$ ALMA images

Exceptionally fast ejecta seen in light echoes of Eta Carinae’s Great Eruption

Light echoes from the plateau in Eta Carinae’s Great Eruption reveal a two-stage shock-powered event

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