Reading between the lines: Disk emission, wind, and accretion during the Z CMa NW outburst

A. Sicilia-Aguilar; J. Bouvier; C. Dougados; K. Grankin; J. F. Donati

doi:10.1051/0004-6361/202038489

Reading between the lines: Disk emission, wind, and accretion during the Z CMa NW outburst

A. Sicilia-Aguilar (Lead / Corresponding author), J. Bouvier, C. Dougados, K. Grankin, J. F. Donati

Physics

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Abstract

Aims: We use optical spectroscopy to investigate the disk, wind, and accretion during the 2008 Z CMa NW outburst.

Methods: Emission lines were used to constrain the locations, densities, and temperatures of the structures around the star.

Results:. More than 1000 optical emission lines reveal accretion, a variable, multicomponent wind, and double-peaked lines of disk origin. The variable, non-axisymmetric, accretion-powered wind has slow (∼0 km s^-1), intermediate (approximately -100 km s^-1), and fast (=-400 km s^-1) components. The fast components are of stellar origin and disappear in quiescence, while the slow component is less variable and could be related to a disk wind. The changes in the optical depth of the lines between outburst and quiescence reveal that increased accretion is responsible for the observed outburst. We derive an accretion rate of 10^-4 M_⊙ yr^-1 in outburst. The Fe I and weak Fe II lines arise from an irradiated, flared disk at ∼0.5 3 × M_∗/16 M_⊙ au with asymmetric upper layers, revealing that the energy from the accretion burst is deposited at scales below 0.5 au. Some line profiles have redshifted asymmetries, but the system is unlikely to be sustained by magnetospheric accretion, especially in outburst. The accretion-related structures extend over several stellar radii and, like the wind, are likely to be non-axisymmetric. The stellar mass may be ∼6 8 M_⊙, lower than previously thought (∼16 M_⊙).

Conclusions: Emission line analysis is found to be a powerful tool to study the innermost regions and accretion in stars within a very large range of effective temperatures. The density ranges in the disk and accretion structures are higher than in late-type stars, but the overall behavior, including the innermost disk emission and variable wind, is very similar for stars with different spectral types. Our work suggests a common outburst behavior for stars with spectral types ranging from M type to intermediate mass.

Original language	English
Article number	A29
Number of pages	27
Journal	Astronomy & Astrophysics
Volume	643
Early online date	28 Oct 2020
DOIs	https://doi.org/10.1051/0004-6361/202038489
Publication status	Published - Nov 2020

Keywords

Accretion, accretion disks
Protoplanetary disks
Stars: individual: Z CMa NW
Stars: pre-main sequence
Stars: variables: T Tauri, Herbig Ae/Be
Techniques: spectroscopic

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1051/0004-6361/202038489

Author Accepted ManuscriptAccepted author manuscript, 18.3 MB

Cite this

@article{b8c06b44b9dc4fcebe70677f337bdea5,

title = "Reading between the lines: Disk emission, wind, and accretion during the Z CMa NW outburst",

abstract = "Aims: We use optical spectroscopy to investigate the disk, wind, and accretion during the 2008 Z CMa NW outburst.Methods: Emission lines were used to constrain the locations, densities, and temperatures of the structures around the star.Results:. More than 1000 optical emission lines reveal accretion, a variable, multicomponent wind, and double-peaked lines of disk origin. The variable, non-axisymmetric, accretion-powered wind has slow (∼0 km s-1), intermediate (approximately -100 km s-1), and fast (=-400 km s-1) components. The fast components are of stellar origin and disappear in quiescence, while the slow component is less variable and could be related to a disk wind. The changes in the optical depth of the lines between outburst and quiescence reveal that increased accretion is responsible for the observed outburst. We derive an accretion rate of 10-4 M⊙ yr-1 in outburst. The Fe I and weak Fe II lines arise from an irradiated, flared disk at ∼0.5 3 × M∗/16 M⊙ au with asymmetric upper layers, revealing that the energy from the accretion burst is deposited at scales below 0.5 au. Some line profiles have redshifted asymmetries, but the system is unlikely to be sustained by magnetospheric accretion, especially in outburst. The accretion-related structures extend over several stellar radii and, like the wind, are likely to be non-axisymmetric. The stellar mass may be ∼6 8 M⊙, lower than previously thought (∼16 M⊙).Conclusions: Emission line analysis is found to be a powerful tool to study the innermost regions and accretion in stars within a very large range of effective temperatures. The density ranges in the disk and accretion structures are higher than in late-type stars, but the overall behavior, including the innermost disk emission and variable wind, is very similar for stars with different spectral types. Our work suggests a common outburst behavior for stars with spectral types ranging from M type to intermediate mass.",

keywords = "Accretion, accretion disks, Protoplanetary disks, Stars: individual: Z CMa NW, Stars: pre-main sequence, Stars: variables: T Tauri, Herbig Ae/Be, Techniques: spectroscopic",

author = "A. Sicilia-Aguilar and J. Bouvier and C. Dougados and K. Grankin and Donati, {J. F.}",

note = "Funding Information: Acknowledgments. We thank Lynne Hillenbrand, Andrew Collier Cameron, Lee Hartmann, Peter Woitke, and Ignacio Mendigut{\'i}a for inspiring discussion, as well as the anonymous referee for valuable comments. A.S.A. is partly supported by the STFC grant number ST/S000399/1 ({\textquoteleft}{\textquoteleft}The Planet-Disk Connection: Accretion, Disk Structure, and Planet Formation”) and by the 2017 Visiting Teacher Campaign at the University of Grenoble. We thank the former OHP Director, Michel Boer, for granting discretionary time to perform these observations. We thank Anne Eggenberger for performing the second set of spectroscopic observations at OHP during quiescence. This project has received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement No 742095; SPIDI: Star-Planets-Inner Disk-Interactions, http://spidi-eu.org, and grant agreement No 740651 NewWorlds). We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research, and in particular, observers from the Royal Astronomical Society of New Zealand (RASNZ). Publisher Copyright: {\textcopyright} 2020 ESO. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.",

year = "2020",

month = nov,

doi = "10.1051/0004-6361/202038489",

language = "English",

volume = "643",

journal = "Astronomy & Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - Reading between the lines

T2 - Disk emission, wind, and accretion during the Z CMa NW outburst

AU - Sicilia-Aguilar, A.

AU - Bouvier, J.

AU - Dougados, C.

AU - Grankin, K.

AU - Donati, J. F.

N1 - Funding Information: Acknowledgments. We thank Lynne Hillenbrand, Andrew Collier Cameron, Lee Hartmann, Peter Woitke, and Ignacio Mendigutía for inspiring discussion, as well as the anonymous referee for valuable comments. A.S.A. is partly supported by the STFC grant number ST/S000399/1 (‘‘The Planet-Disk Connection: Accretion, Disk Structure, and Planet Formation”) and by the 2017 Visiting Teacher Campaign at the University of Grenoble. We thank the former OHP Director, Michel Boer, for granting discretionary time to perform these observations. We thank Anne Eggenberger for performing the second set of spectroscopic observations at OHP during quiescence. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 742095; SPIDI: Star-Planets-Inner Disk-Interactions, http://spidi-eu.org, and grant agreement No 740651 NewWorlds). We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research, and in particular, observers from the Royal Astronomical Society of New Zealand (RASNZ). Publisher Copyright: © 2020 ESO. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/11

Y1 - 2020/11

N2 - Aims: We use optical spectroscopy to investigate the disk, wind, and accretion during the 2008 Z CMa NW outburst.Methods: Emission lines were used to constrain the locations, densities, and temperatures of the structures around the star.Results:. More than 1000 optical emission lines reveal accretion, a variable, multicomponent wind, and double-peaked lines of disk origin. The variable, non-axisymmetric, accretion-powered wind has slow (∼0 km s-1), intermediate (approximately -100 km s-1), and fast (=-400 km s-1) components. The fast components are of stellar origin and disappear in quiescence, while the slow component is less variable and could be related to a disk wind. The changes in the optical depth of the lines between outburst and quiescence reveal that increased accretion is responsible for the observed outburst. We derive an accretion rate of 10-4 M⊙ yr-1 in outburst. The Fe I and weak Fe II lines arise from an irradiated, flared disk at ∼0.5 3 × M∗/16 M⊙ au with asymmetric upper layers, revealing that the energy from the accretion burst is deposited at scales below 0.5 au. Some line profiles have redshifted asymmetries, but the system is unlikely to be sustained by magnetospheric accretion, especially in outburst. The accretion-related structures extend over several stellar radii and, like the wind, are likely to be non-axisymmetric. The stellar mass may be ∼6 8 M⊙, lower than previously thought (∼16 M⊙).Conclusions: Emission line analysis is found to be a powerful tool to study the innermost regions and accretion in stars within a very large range of effective temperatures. The density ranges in the disk and accretion structures are higher than in late-type stars, but the overall behavior, including the innermost disk emission and variable wind, is very similar for stars with different spectral types. Our work suggests a common outburst behavior for stars with spectral types ranging from M type to intermediate mass.

AB - Aims: We use optical spectroscopy to investigate the disk, wind, and accretion during the 2008 Z CMa NW outburst.Methods: Emission lines were used to constrain the locations, densities, and temperatures of the structures around the star.Results:. More than 1000 optical emission lines reveal accretion, a variable, multicomponent wind, and double-peaked lines of disk origin. The variable, non-axisymmetric, accretion-powered wind has slow (∼0 km s-1), intermediate (approximately -100 km s-1), and fast (=-400 km s-1) components. The fast components are of stellar origin and disappear in quiescence, while the slow component is less variable and could be related to a disk wind. The changes in the optical depth of the lines between outburst and quiescence reveal that increased accretion is responsible for the observed outburst. We derive an accretion rate of 10-4 M⊙ yr-1 in outburst. The Fe I and weak Fe II lines arise from an irradiated, flared disk at ∼0.5 3 × M∗/16 M⊙ au with asymmetric upper layers, revealing that the energy from the accretion burst is deposited at scales below 0.5 au. Some line profiles have redshifted asymmetries, but the system is unlikely to be sustained by magnetospheric accretion, especially in outburst. The accretion-related structures extend over several stellar radii and, like the wind, are likely to be non-axisymmetric. The stellar mass may be ∼6 8 M⊙, lower than previously thought (∼16 M⊙).Conclusions: Emission line analysis is found to be a powerful tool to study the innermost regions and accretion in stars within a very large range of effective temperatures. The density ranges in the disk and accretion structures are higher than in late-type stars, but the overall behavior, including the innermost disk emission and variable wind, is very similar for stars with different spectral types. Our work suggests a common outburst behavior for stars with spectral types ranging from M type to intermediate mass.

KW - Accretion, accretion disks

KW - Protoplanetary disks

KW - Stars: individual: Z CMa NW

KW - Stars: pre-main sequence

KW - Stars: variables: T Tauri, Herbig Ae/Be

KW - Techniques: spectroscopic

UR - https://arxiv.org/abs/2008.13678

UR - http://www.scopus.com/inward/record.url?scp=85095693796&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/202038489

DO - 10.1051/0004-6361/202038489

M3 - Article

AN - SCOPUS:85095693796

SN - 0004-6361

VL - 643

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A29

ER -

Reading between the lines: Disk emission, wind, and accretion during the Z CMa NW outburst

Abstract

Keywords

ASJC Scopus subject areas

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The Planet-Disc Connection: Accretion, Disc Structure and Plant Formation

"Leyendo entre líneas": Cómo usar el tiempo para cartografiar el espacio

"Reading between the lines": Using time measurements to map space

"Reading between the lines": Probing magnetospheric accretion, winds, and the innermost disk with emission line tomography

Cite this

Reading between the lines: Disk emission, wind, and accretion during the Z CMa NW outburst

Abstract

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Projects

The Planet-Disc Connection: Accretion, Disc Structure and Plant Formation

Activities

"Leyendo entre líneas": Cómo usar el tiempo para cartografiar el espacio

"Reading between the lines": Using time measurements to map space

"Reading between the lines": Probing magnetospheric accretion, winds, and the innermost disk with emission line tomography

Cite this