The 2008 outburst in the Young Stellar System Z CMa. III - Multi-epoch high-angular resolution images and spectra of the components in near-infrared

Abstract

Z CMa is a complex pre-main sequence binary with a current separation of 100 mas, known to consist of an FU Orionis star (SE component) and an embedded Herbig Be star (NW component). Immediately when the late-2008 outburst of Z CMa was announced to the community, we initiated a high angular resolution imaging campaign with VLT/NaCo, Keck/NIRC2, VLT/SINFONI, and Keck/OSIRIS which aimed at characterizing the outburst of both components of the system in the near-infrared. We confirm that the NW star dominates the system flux in the 1.1-3.8 microns range and is responsible for the photometric outburst. We extract the first medium-resolution (R=2000-4000) near-infrared (1.1-2.4 microns) spectra of the individual components during and after the outburst. The SE component has a spectrum typical of FU Orionis objects. The NW component spectrum is characteristic of embedded outbursting protostars and EX Or objects. It displays numerous emission lines during the outburst whose intensity correlates with the system activity. In particular, we find a correlation between the Brackett gamma equivalent width and the system brightness. The bluing of the continuum of the NW component along with the absolute flux and color-variation of the system during the outburst suggests that the outburst was caused by a complex interplay between a variation of the extinction in the line of sight of the NW component on one hand, and the emission of shocked regions close to the NW component on the other. We confirm the recently reported wiggling of the SE component jet from [Fe II] line emission. We find a point-like structure associated with a peak emission at 2.098 microns coincidental with the clump or arm seen in broadband polarization differential imaging as well as additional diffuse emission along a PA=214 degrees. The origin of these two structures is unclear and deserves further investigation.

18 pages, 18 figures, 7 tables. Accepted for publication in Astronomy and Astrophysics

References in corpus (43)

• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits
• The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars
• Spatially Resolved Circumstellar Structure of Herbig Ae/Be Stars in the Near-Infrared
• A Spectroscopic Survey of Subarcsecond Binaries in the Taurus-Auriga Dark Cloud with the Hubble Space Telescope
• Accretion Discs Trapped Near Corotation
• The near-infrared size-luminosity relations for Herbig Ae/Be disks
• A library of near-infrared integral field spectra of young M-L dwarfs
• A Near-Infrared Spectroscopic Survey of Class I Protostars
• Circumstellar disks around Herbig Be stars
• The outburst and nature of two young eruptive stars in the North America/Pelican Nebula Complex
• The RMS Survey: Near-IR Spectroscopy of Massive Young Stellar Objects
• Probing the embedded YSOs of the R CrA region through VLT-ISAAC spectroscopy
• Circumstellar Disks of the Most Vigorously Accreting Young Stars
• Accretion and ejection properties of embedded protostars: the case of HH26, HH34 and HH46 IRS
• Near Infrared Spectroscopic Monitoring of EXor variables: First Results
• On the nature of the EXor accretion events: an unfrequent manifestation of a common phenomenology ?
• PTF10nvg: An Outbursting Class I Protostar in the Pelican/North American Nebula
• Highly Variable Extinction and Accretion in the Jet-driving Class I Type Young Star PTF 10nvg (V2492 Cyg, IRAS 20496+4354)
• POISSON project - I - Emission lines as accretion tracers in young stellar objects: results from observations of Chamaeleon I and II sources
• Constraining the Sub-AU-Scale Distribution of Hydrogen and Carbon Monoxide Gas around Young Stars with the Keck Interferometer
• High Resolution Near-Infrared Spectroscopy of FUors and FUor-like stars
• The Stellar Composition of the Star Formation Region CMa R1 -- III. A new outburst of the Be star component in Z CMa
• The 2008 Outburst in the Young Stellar System Z CMa: The First Detection of Twin Jets
• Keck Interferometer Observations of FU Orionis Objects
• Near-infrared spectroscopy of EX Lupi in outburst
• The 2008 outburst in the young stellar system ZCMa: I. Evidence of an enhanced bipolar wind on the AU-scale
• The X-ray emission from Z CMa during an FUor-like outburst and the detection of its X-ray jet
• Exploring the circumstellar environment of the young eruptive star V2492 Cyg
• Depletion of molecular gas by an accretion outburst in a protoplanetary disk
• Evidence for T Tauri-like emission in the EXor V1118 Ori from near-IR and X-ray data
• The nature of the recent extreme outburst of the Herbig Be/FU Ori binary Z CMa
• Discovery of a Near-Infrared Jet-Like Feature in the Z Canis Majoris System
• Near-infrared integral field spectroscopy of Massive Young Stellar Objects
• The inner environment of Z~CMa: High-Contrast Imaging Polarimetry with NaCo
• LBT/LUCIFER near-infrared spectroscopy of PV Cephei. An outbursting young stellar object with an asymmetric jet
• Sub-0.1" optical imaging of the Z CMa jets with SPHERE/ZIMPOL
• High Resolution Infrared Imaging & Spectroscopy of the Z Canis Majoris System During Quiescence & Outburst
• Constraining the Circumbinary Envelope of Z CMa via imaging polarimetry
• On the 2015 outburst of the EXor variable star V1118 Ori
• De-biasing interferometric visibilities in VLTI-AMBER data of low SNR observations
• A new insight into the V1184 Tau variability
• Characterisation of close visual binaries from the AstraLux Large M Dwarf Survey

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• The 2014-2017 outburst of the young star ASASSN-13db: A time-resolved picture of a very low-mass star between EXors and FUors
• Sustained FU Orionis-type outbursts from colliding discs in stellar flybys
• Sub-0.1" optical imaging of the Z CMa jets with SPHERE/ZIMPOL
• Dynamical masses of M-dwarf binaries in young moving groups: I - The case of TWA 22 and GJ 2060
• Spectroscopic confirmation of high-amplitude eruptive YSOs and dipping giants from the VVV survey
• CS Cha B: A disc-obscured M-type star mimicking a polarised planetary companion
• Reading between the lines: Disk emission, wind, and accretion during the ZCMa NW outburst
• The Effelsberg survey of FU~Orionis and EX~Lupi objects II. -- H${}_2$O maser observations
• Large-Scale Ejecta of Z CMa -- Proper Motion Study and New Features Discovered