Protostellar accretion traced with chemistry: high-resolution C18O and continuum observations towards deeply embedded protostars in Perseus

Søren Frimann; Jes Kristian Jørgensen; Michael M. Dunham; Tyler L. Bourke; Lars Egstrøm Kristensen; Stella S. R. Offner; Ian W. Stephens; John J. Tobin; Eduard I. Vorobyov

doi:10.1051/0004-6361/201629739

Protostellar accretion traced with chemistry: high-resolution C¹⁸O and continuum observations towards deeply embedded protostars in Perseus

Søren Frimann, Jes Kristian Jørgensen, Michael M. Dunham, Tyler L. Bourke, Lars Egstrøm Kristensen, Stella S. R. Offner, Ian W. Stephens, John J. Tobin, Eduard I. Vorobyov

Astrophysics and Planetary Science

26 Citations (Scopus)

13 Downloads (Pure)

Abstract

Context. Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in the earliest stages of star formation. Aims. Our aim is to characterise protostellar accretion histories towards individual sources by utilising sublimation and freeze-out chemistry of CO. Methods. A sample of 24 embedded protostars are observed with the Submillimeter Array (SMA) in context of the large program "Mass Assembly of Stellar Systems and their Evolution with the SMA" (MASSES). The size of the C¹⁸O-emitting region, where CO has sublimated into the gas-phase, is measured towards each source and compared to the expected size of the region given the current luminosity. The SMA observations also include 1.3 mm continuum data, which are used to investigate whether or not a link can be established between accretion bursts and massive circumstellar disks. Results. Depending on the adopted sublimation temperature of the CO ice, between 20% and 50% of the sources in the sample show extended C¹⁸O emission indicating that the gas was warm enough in the past that CO sublimated and is currently in the process of refreezing; something which we attribute to a recent accretion burst. Given the fraction of sources with extended C¹⁸O emission, we estimate an average interval between bursts of 20 000-50 000 yr, which is consistent with previous estimates. No clear link can be established between the presence of circumstellar disks and accretion bursts, however the three closest known binaries in the sample (projected separations <20 AU) all show evidence of a past accretion burst, indicating that close binary interactions may also play a role in inducing accretion variability.

Original language	English
Article number	A120
Journal	Astronomy and Astrophysics
Volume	602
Number of pages	21
ISSN	0004-6361
DOIs	https://doi.org/10.1051/0004-6361/201629739
Publication status	Published - Jun 2017

Keywords

Circumstellar matter
ISM: molecules
Protoplanetary disks
Stars: formation
Stars: protostars

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10.1051/0004-6361/201629739

Frimann_2017_Protostellar_accretion_tracedFinal published version, 3.55 MBLicence: Other

http://arxiv.org/pdf/1703.10225Licence: Other

Cite this

Frimann, S., Jørgensen, J. K., Dunham, M. M., Bourke, T. L., Kristensen, L. E., Offner, S. S. R., Stephens, I. W., Tobin, J. J., & Vorobyov, E. I. (2017). Protostellar accretion traced with chemistry: high-resolution C¹⁸O and continuum observations towards deeply embedded protostars in Perseus. Astronomy and Astrophysics, 602, [A120]. https://doi.org/10.1051/0004-6361/201629739

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title = "Protostellar accretion traced with chemistry: high-resolution C18O and continuum observations towards deeply embedded protostars in Perseus",

abstract = "Context. Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in the earliest stages of star formation. Aims. Our aim is to characterise protostellar accretion histories towards individual sources by utilising sublimation and freeze-out chemistry of CO. Methods. A sample of 24 embedded protostars are observed with the Submillimeter Array (SMA) in context of the large program {"}Mass Assembly of Stellar Systems and their Evolution with the SMA{"} (MASSES). The size of the C18O-emitting region, where CO has sublimated into the gas-phase, is measured towards each source and compared to the expected size of the region given the current luminosity. The SMA observations also include 1.3 mm continuum data, which are used to investigate whether or not a link can be established between accretion bursts and massive circumstellar disks. Results. Depending on the adopted sublimation temperature of the CO ice, between 20% and 50% of the sources in the sample show extended C18O emission indicating that the gas was warm enough in the past that CO sublimated and is currently in the process of refreezing; something which we attribute to a recent accretion burst. Given the fraction of sources with extended C18O emission, we estimate an average interval between bursts of 20 000-50 000 yr, which is consistent with previous estimates. No clear link can be established between the presence of circumstellar disks and accretion bursts, however the three closest known binaries in the sample (projected separations <20 AU) all show evidence of a past accretion burst, indicating that close binary interactions may also play a role in inducing accretion variability.",

keywords = "Circumstellar matter, ISM: molecules, Protoplanetary disks, Stars: formation, Stars: protostars",

author = "S{\o}ren Frimann and J{\o}rgensen, {Jes Kristian} and Dunham, {Michael M.} and Bourke, {Tyler L.} and Kristensen, {Lars Egstr{\o}m} and Offner, {Stella S. R.} and Stephens, {Ian W.} and Tobin, {John J.} and Vorobyov, {Eduard I.}",

year = "2017",

month = jun,

doi = "10.1051/0004-6361/201629739",

language = "English",

volume = "602",

journal = "Astronomy and Astrophysics Supplement Series",

issn = "0004-6361",

publisher = "E D P Sciences",

}

TY - JOUR

T1 - Protostellar accretion traced with chemistry

T2 - high-resolution C18O and continuum observations towards deeply embedded protostars in Perseus

AU - Frimann, Søren

AU - Jørgensen, Jes Kristian

AU - Dunham, Michael M.

AU - Bourke, Tyler L.

AU - Kristensen, Lars Egstrøm

AU - Offner, Stella S. R.

AU - Stephens, Ian W.

AU - Tobin, John J.

AU - Vorobyov, Eduard I.

PY - 2017/6

Y1 - 2017/6

N2 - Context. Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in the earliest stages of star formation. Aims. Our aim is to characterise protostellar accretion histories towards individual sources by utilising sublimation and freeze-out chemistry of CO. Methods. A sample of 24 embedded protostars are observed with the Submillimeter Array (SMA) in context of the large program "Mass Assembly of Stellar Systems and their Evolution with the SMA" (MASSES). The size of the C18O-emitting region, where CO has sublimated into the gas-phase, is measured towards each source and compared to the expected size of the region given the current luminosity. The SMA observations also include 1.3 mm continuum data, which are used to investigate whether or not a link can be established between accretion bursts and massive circumstellar disks. Results. Depending on the adopted sublimation temperature of the CO ice, between 20% and 50% of the sources in the sample show extended C18O emission indicating that the gas was warm enough in the past that CO sublimated and is currently in the process of refreezing; something which we attribute to a recent accretion burst. Given the fraction of sources with extended C18O emission, we estimate an average interval between bursts of 20 000-50 000 yr, which is consistent with previous estimates. No clear link can be established between the presence of circumstellar disks and accretion bursts, however the three closest known binaries in the sample (projected separations <20 AU) all show evidence of a past accretion burst, indicating that close binary interactions may also play a role in inducing accretion variability.

AB - Context. Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in the earliest stages of star formation. Aims. Our aim is to characterise protostellar accretion histories towards individual sources by utilising sublimation and freeze-out chemistry of CO. Methods. A sample of 24 embedded protostars are observed with the Submillimeter Array (SMA) in context of the large program "Mass Assembly of Stellar Systems and their Evolution with the SMA" (MASSES). The size of the C18O-emitting region, where CO has sublimated into the gas-phase, is measured towards each source and compared to the expected size of the region given the current luminosity. The SMA observations also include 1.3 mm continuum data, which are used to investigate whether or not a link can be established between accretion bursts and massive circumstellar disks. Results. Depending on the adopted sublimation temperature of the CO ice, between 20% and 50% of the sources in the sample show extended C18O emission indicating that the gas was warm enough in the past that CO sublimated and is currently in the process of refreezing; something which we attribute to a recent accretion burst. Given the fraction of sources with extended C18O emission, we estimate an average interval between bursts of 20 000-50 000 yr, which is consistent with previous estimates. No clear link can be established between the presence of circumstellar disks and accretion bursts, however the three closest known binaries in the sample (projected separations <20 AU) all show evidence of a past accretion burst, indicating that close binary interactions may also play a role in inducing accretion variability.

KW - Circumstellar matter

KW - ISM: molecules

KW - Protoplanetary disks

KW - Stars: formation

KW - Stars: protostars

U2 - 10.1051/0004-6361/201629739

DO - 10.1051/0004-6361/201629739

M3 - Journal article

AN - SCOPUS:85021656422

SN - 0004-6361

VL - 602

JO - Astronomy and Astrophysics Supplement Series

JF - Astronomy and Astrophysics Supplement Series

M1 - A120

ER -