Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone

Context. The central molecular zone (CMZ) is a similar to 200 pc region around the Galactic centre. The study of star formation in the central part of the Milky Way is of great interest as it provides a template for the closest galactic nuclei. Aims. We present a spectroscopic follow-up of photometr...

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Autores: Nandakumar, G., Schultheis, Mathias, Feldmeier-Krause, A., Schödel, Rainer, Neumayer, N., Matteucci, F, Ryde, N, Rojas-Arriagada, A, Tej, A
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2018
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/160525
Acceso en línea:http://hdl.handle.net/10261/160525
Access Level:acceso abierto
Palabra clave:Galaxy: center
Galaxy: stellar content
Stars: formation
Stars: massive
Stars: pre-main sequence
Hertzsprung-Russell and C-M diagrams
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repository_id_str
spelling Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zoneNandakumar, G.Schultheis, MathiasFeldmeier-Krause, A.Schödel, RainerNeumayer, N.Matteucci, FRyde, NRojas-Arriagada, ATej, AGalaxy: centerGalaxy: stellar contentStars: formationStars: massiveStars: pre-main sequenceHertzsprung-Russell and C-M diagramsContext. The central molecular zone (CMZ) is a similar to 200 pc region around the Galactic centre. The study of star formation in the central part of the Milky Way is of great interest as it provides a template for the closest galactic nuclei. Aims. We present a spectroscopic follow-up of photometrically selected young stellar object (YSO) candidates in the CMZ of the Galactic centre. Our goal is to quantify the contamination of this YSO sample by reddened giant stars with circumstellar envelopes and to determine the star formation rate (SFR) in the CMZ. Methods. We obtained KMOS low-resolution near-infrared spectra (R similar to 4000) between 2.0 and 2.5 mu m of sources, many of which have been previously identified by mid-infrared photometric criteria as massive YSOs in the Galactic centre. Our final sample consists of 91 stars with good signal-to-noise ratio. We separated YSOs from cool late-type stars based on spectral features of CO and Br gamma at 2.3 mu m and 2.16 mu m, respectively. We made use of spectral energy distribution (SED) model fits to the observed photometric data points from 1.25 to 24 mu m to estimate approximate masses for the YSOs. Results. Using the spectroscopically identified YSOs in our sample, we confirm that existing colour-colour diagrams and colour-magnitude diagrams are unable to efficiently separate YSOs and cool late-type stars. In addition, we define a new colour-colour criterion that separates YSOs from cool late-type stars in the H - K-S vs. H-[8.0] diagram. We use this new criterion to identify YSO candidates in the vertical bar l vertical bar < 1.5, vertical bar b vertical bar < 0.5 region and use model SED fits to estimate their approximate masses. By assuming an appropriate initial mass function (IMF) and extrapolating the stellar IMF down to lower masses, we determine a SFR of similar to 0.046 +/- 0.026 M-circle dot yr (1) assuming an average age of 0.75 +/- 0.25 Myr for the YSOs. This value is lower than estimates found using the YSO counting method in the literature. Conclusions. Our SFR estimate in the CMZ agrees with the previous estimates from various methods and reaffirms that star formation in the CMZ is proceeding at a lower rate than predicted by various star forming models.© ESO, 2018.G.N. and M.S. acknowledges the Programme National de Cosmologie et Galaxies (PNCG) of CNRS/INSU, France, for financial support. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. [614922].Peer reviewedEDP SciencesCentre National de la Recherche Scientifique (France)European Research CouncilConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]201820182018info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/160525reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/EC/FP7/614922http://dx.doi.org/10.1051/0004-6361/201731918Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/1605252026-05-22T06:33:51Z
dc.title.none.fl_str_mv Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
title Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
spellingShingle Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
Nandakumar, G.
Galaxy: center
Galaxy: stellar content
Stars: formation
Stars: massive
Stars: pre-main sequence
Hertzsprung-Russell and C-M diagrams
title_short Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
title_full Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
title_fullStr Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
title_full_unstemmed Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
title_sort Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
dc.creator.none.fl_str_mv Nandakumar, G.
Schultheis, Mathias
Feldmeier-Krause, A.
Schödel, Rainer
Neumayer, N.
Matteucci, F
Ryde, N
Rojas-Arriagada, A
Tej, A
author Nandakumar, G.
author_facet Nandakumar, G.
Schultheis, Mathias
Feldmeier-Krause, A.
Schödel, Rainer
Neumayer, N.
Matteucci, F
Ryde, N
Rojas-Arriagada, A
Tej, A
author_role author
author2 Schultheis, Mathias
Feldmeier-Krause, A.
Schödel, Rainer
Neumayer, N.
Matteucci, F
Ryde, N
Rojas-Arriagada, A
Tej, A
author2_role author
author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv Centre National de la Recherche Scientifique (France)
European Research Council
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Galaxy: center
Galaxy: stellar content
Stars: formation

Stars: massive
Stars: pre-main sequence
Hertzsprung-Russell and C-M diagrams
topic Galaxy: center
Galaxy: stellar content
Stars: formation
Stars: massive
Stars: pre-main sequence
Hertzsprung-Russell and C-M diagrams
description Context. The central molecular zone (CMZ) is a similar to 200 pc region around the Galactic centre. The study of star formation in the central part of the Milky Way is of great interest as it provides a template for the closest galactic nuclei. Aims. We present a spectroscopic follow-up of photometrically selected young stellar object (YSO) candidates in the CMZ of the Galactic centre. Our goal is to quantify the contamination of this YSO sample by reddened giant stars with circumstellar envelopes and to determine the star formation rate (SFR) in the CMZ. Methods. We obtained KMOS low-resolution near-infrared spectra (R similar to 4000) between 2.0 and 2.5 mu m of sources, many of which have been previously identified by mid-infrared photometric criteria as massive YSOs in the Galactic centre. Our final sample consists of 91 stars with good signal-to-noise ratio. We separated YSOs from cool late-type stars based on spectral features of CO and Br gamma at 2.3 mu m and 2.16 mu m, respectively. We made use of spectral energy distribution (SED) model fits to the observed photometric data points from 1.25 to 24 mu m to estimate approximate masses for the YSOs. Results. Using the spectroscopically identified YSOs in our sample, we confirm that existing colour-colour diagrams and colour-magnitude diagrams are unable to efficiently separate YSOs and cool late-type stars. In addition, we define a new colour-colour criterion that separates YSOs from cool late-type stars in the H - K-S vs. H-[8.0] diagram. We use this new criterion to identify YSO candidates in the vertical bar l vertical bar < 1.5, vertical bar b vertical bar < 0.5 region and use model SED fits to estimate their approximate masses. By assuming an appropriate initial mass function (IMF) and extrapolating the stellar IMF down to lower masses, we determine a SFR of similar to 0.046 +/- 0.026 M-circle dot yr (1) assuming an average age of 0.75 +/- 0.25 Myr for the YSOs. This value is lower than estimates found using the YSO counting method in the literature. Conclusions. Our SFR estimate in the CMZ agrees with the previous estimates from various methods and reaffirms that star formation in the CMZ is proceeding at a lower rate than predicted by various star forming models.© ESO, 2018.
publishDate 2018
dc.date.none.fl_str_mv 2018
2018
2018
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/160525
url http://hdl.handle.net/10261/160525
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/EC/FP7/614922
http://dx.doi.org/10.1051/0004-6361/201731918
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,81155

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