Ancient eruptions of Eta Carinae: A tale written in proper motions

Abstract

We analyze eight epochs of Hubble Space Telescope H$\alpha$+[N II] imaging of Eta Carinae's outer ejecta. Proper motions of nearly 800 knots reveal that the detected ejecta are divided into three apparent age groups, dating to around 1250 A.D., to around 1550 A.D., and to during or shortly before the Great Eruption of the 1840s. Ejecta from these groups reside in different locations and provide a firm constraint that Eta Car experienced multiple major eruptions prior to the 19th century. The 1250 and 1550 events did not share the same axisymmetry as the Homunculus; the 1250 event was particularly asymmetric, even one-sided. In addition, the ejecta in the S ridge, which have been associated with the Great Eruption, appear to predate the ejection of the Homunculus by several decades. We detect essentially ballistic expansion across multiple epochs. We find no evidence for large-scale deceleration of the observed knots that could power the soft X-ray shell by plowing into surrounding material, suggesting that the observed X-rays arise instead from fast, rarefied ejecta from the 1840s overtaking the older dense knots. Early deceleration and subsequent coasting cannot explain the origin of the older outer ejecta---significant episodic mass loss prior to the 19th century is required. The timescale and geometry of the past eruptions provide important constraints for any theoretical physical mechanisms driving Eta Car's behavior. Non-repeating mechanisms such as the merger of a close binary in a triple system would require additional complexities to explain the observations.

arXiv comment14 pages, 11 figures, accepted for publication in MNRAS

References in corpus (30)

• An ACS Survey of Globular Clusters V: Star Catalog for Each Cluster
• Toward High-Precision Astrometry with WFPC2. I. Deriving an Accurate PSF
• The Structure of the Homunculus: I. Shape and Latitude Dependence from H2 and [Fe II] Velocity Maps of Eta Carinae
• New Limits on an Intermediate Mass Black Hole in Omega Centauri: I. Hubble Space Telescope Photometry and Proper Motions
• A Porosity-Length Formalism for Photon-Tiring-Limited Mass Loss from Stars Above the Eddington Limit
• Luminous Blue Variables are Antisocial: Their Isolation Implies that they are Kicked Mass Gainers in Binary Evolution
• A Census of the Carina Nebula. I: Cumulative Energy Input from Massive Stars
• Eta Carinae: Binarity Confirmed
• The M31 Velocity Vector. I. Hubble Space Telescope Proper Motion Measurements
• The porous atmosphere of eta Carinae
• A Revised Historical Light Curve of Eta Carinae and the Timing of Close Periastron Encounters
• A Blast Wave from the 1843 Eruption of Eta Carinae
• Periastron Passage Triggering of the 19th Century Eruptions of Eta Carinae
• Infrared [Fe II] emission from P Cygni's nebula: Atomic data, mass, kinematics, and the 1600 A.D. outburst
• HST/ACS H-alpha Imaging of the Carina Nebula: Outflow Activity Traced by Irradiated Herbig-Haro Jets
• The 2003 Shell Event in eta Carinae
• A Deep HST Study of the Globular Cluster NGC 6397: Reduction Methods
• Explosions Triggered by Violent Binary-Star Collisions: Application to Eta Carinae and other Eruptive Transients
• Nitrogen and Oxygen Abundance Variations in the Outer Ejecta of Eta Carinae: Evidence for Recent Chemical Enrichment
• Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?
• Doppler tomography of the Little Homunculus: High resolution spectra of [Fe II] 16435 around Eta Carinae
• Early Chandra X-ray Observations of Eta Carinae
• Submillimetre Variability of Eta Carinae: cool dust within the outer ejecta
• High velocity structures in, and the X-ray emission from the LBV nebula around Eta Carinae
• Comparing Eta Carinae with the Red Rectangle
• Highly supersonic motions within the outer features of the Eta Carinae nebulosity
• HH 666: Different kinematics from Hα and [Fe II] emission provide a missing link between jets and outflows
• Disentangling the outflow and protostars in HH 900 in the Carina Nebula
• The [O III] Veil: Astropause of Eta Carinae's Wind?
• Kinematics of powerful jets from intermediate-mass protostars in the Carina nebula

Cited by in corpus (31)

• Pulsational Pair-Instability Supernovae
• Episodic mass ejections from common-envelope objects
• Light-echoes from the plateau in Eta Carinae's Great Eruption reveal a two-stage shock-powered event
• SN 2015bh: NGC 2770's 4th supernova or a luminous blue variable on its way to a Wolf-Rayet star?
• Simulating the formation of $\eta$ Carinae's surrounding nebula through unstable triple evolution and stellar merger-induced eruption
• The Villafranca catalog of Galactic OB groups. II. From Gaia DR2 to EDR3 and ten new systems with O stars
• Optical and IR observations of SN 2013L, a Type IIn Supernova surrounded by asymmetric CSM
• High-resolution spectroscopy of SN 2017hcc and its blueshifted line profiles from post-shock dust formation
• SN2012ab: A Peculiar Type IIn Supernova with Aspherical Circumstellar Material
• Exceptionally fast ejecta seen in light echoes of Eta Carinae's Great Eruption
• Proper motions of collimated jets from intermediate-mass protostars in the Carina Nebula
• Distinguishing Circumstellar from Stellar Photometric Variability in Eta Carinae
• A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA
• Deep diving off the `Cosmic Cliffs': previously hidden outflows in NGC 3324 revealed by JWST
• The Blue Supergiant Progenitor of the Supernova Imposter AT~2019krl
• An outburst powered by the merging of two stars inside the envelope of a giant
• A moderately precise dynamical age for the Homunculus of Eta Carinae based on 13 years of HST imaging
• Eta Carinae & the Homunculus: Far Infrared, Sub-millimeter Spectral Lines
• Fast Ejecta Resulted from Jet-Wind Interaction in the Great Eruption of Eta Carinae
• The peculiar chemistry of the inner ejecta of Eta Carina
• Dissecting a SN impostor's circumstellar medium: MUSEing about the SHAPE of eta Car's outer ejecta
• Luminous Blue Variables
• Ultraviolet Mg II emission from fast neutral ejecta around Eta Carinae
• NICER X-ray Observations of Eta Carinae During its Most Recent Periastron Passage
• Proper motions of five OB stars with candidate dusty bow shocks in the Carina Nebula
• Changes in the Na D${}_1$ Absorption Components of $\eta$ Carinae Provide Clues on the Location of the Dissipating Central Occulter
• HST Proper Motion Measurements of Supernova Remnant N132D: Center of Expansion and Age
• Resolving the H-alpha-emitting Region in the Wind of Eta Carinae
• The Dusty Silhouette Jet HH 1019 in the Carina Nebula
• Godzilla, a monster lurks in the Sunburst galaxy
• Eta Carinae: an evolving view of the central binary, its interacting winds and its foreground ejecta