TY - JOUR
T1 - A discontinuity in the Teff-radius relation of M-dwarfs
AU - Rabus, Markus
AU - Lachaume, Régis
AU - Jordán, Andrés
AU - Brahm, Rafael
AU - Boyajian, Tabetha
AU - Von Braun, Kaspar
AU - Espinoza, Néstor
AU - Berger, Jean Philippe
AU - Le Bouquin, Jean Baptiste
AU - Absil, Olivier
N1 - Funding Information:
We thank the reviewer for their helpful comments on the manuscript. MR acknowledges support from CONICYT project Basal AFB-170002. Partially based on observations obtained via ESO under program IDs 090.D-0917, 091.D-0584, 092.D-0647, 093.D-0471. AJ acknowledges support from FONDECYT project 1171208, CONICYT project BASAL AFB-170002, and by the Ministry for the Economy, Development, and Tourism’s Programa Inicia-tiva Científica Milenio through grant IC 120009, awarded to the Millennium Institute of Astrophysics (MAS). RB acknowledges additional support from project IC120009 ‘Millenium Institute of Astrophysics (MAS)’ of the Millennium Science Initiative, Chilean Ministry of Economy. This work made use of the Smithso-nian/NASA Astrophysics Data System (ADS) and of the Centre de Données astronomiques de Strasbourg (CDS). This research made use of ASTROPY, a community-developed core PYTHON package for Astronomy (ASTROPY Collaboration, 2013). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; ht tps://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Funding Information:
We thank the reviewer for their helpful comments on the manuscript. MR acknowledges support from CONICYT project Basal AFB-170002. Partially based on observations obtained via ESO under program IDs 090.D-0917, 091.D-0584, 092.D-0647, 093.D-0471. AJ acknowledges support from FONDECYT project 1171208, CONICYT project BASAL AFB-170002, and by the Ministry for the Economy, Development, and Tourism's Programa Inicia-tiva Científica Milenio through grant IC 120009, awarded to the Millennium Institute of Astrophysics (MAS). RB acknowledges additional support from project IC120009 'Millenium Institute of Astrophysics (MAS)' of the Millennium Science Initiative, Chilean Ministry of Economy. This work made use of the Smithsonian/NASA Astrophysics Data System (ADS) and of the Centre de Données astronomiques de Strasbourg (CDS). This research made use of ASTROPY, a community-developed core PYTHON package for Astronomy (ASTROPY Collaboration, 2013). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; ht tps://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Publisher Copyright:
© 2018 The Author(s).
PY - 2019/4/1
Y1 - 2019/4/1
N2 - We report on 13 new high-precision measurements of stellar diameters for low-mass dwarfs obtained by means of near-infrared long-baseline interferometry with PIONIER at the Very Large Telescope Interferometer. Together with accurate parallaxes from Gaia DR2, these measurements provide precise estimates for their linear radii, effective temperatures, masses, and luminosities. This allows us to refine the effective temperature scale, in particular towards the coolest M-dwarfs. We measure for late-type stars with enhanced metallicity slightly inflated radii, whereas for stars with decreased metallicity we measure smaller radii. We further show that Gaia DR2 effective temperatures for M-dwarfs are underestimated by ∼8.2 per cent and give an empirical MG-Teff relation that is better suited for M-dwarfs with Teff between 2600 and 4000 K. Most importantly, we are able to observationally identify a discontinuity in the Teff-radius plane, which is likely due to the transition from partially convective M-dwarfs to the fully convective regime. We found this transition to happen between 3200 and 3340 K, or equivalently for stars with masses ≈0.23 M. We find that in this transition region the stellar radii are in the range from 0.18 to 0.42 R for similar stellar effective temperatures.
AB - We report on 13 new high-precision measurements of stellar diameters for low-mass dwarfs obtained by means of near-infrared long-baseline interferometry with PIONIER at the Very Large Telescope Interferometer. Together with accurate parallaxes from Gaia DR2, these measurements provide precise estimates for their linear radii, effective temperatures, masses, and luminosities. This allows us to refine the effective temperature scale, in particular towards the coolest M-dwarfs. We measure for late-type stars with enhanced metallicity slightly inflated radii, whereas for stars with decreased metallicity we measure smaller radii. We further show that Gaia DR2 effective temperatures for M-dwarfs are underestimated by ∼8.2 per cent and give an empirical MG-Teff relation that is better suited for M-dwarfs with Teff between 2600 and 4000 K. Most importantly, we are able to observationally identify a discontinuity in the Teff-radius plane, which is likely due to the transition from partially convective M-dwarfs to the fully convective regime. We found this transition to happen between 3200 and 3340 K, or equivalently for stars with masses ≈0.23 M. We find that in this transition region the stellar radii are in the range from 0.18 to 0.42 R for similar stellar effective temperatures.
KW - Stars: fundamental parameters
KW - Stars: late-type
KW - Stars: low-mass
KW - Techniques: interferometric
UR - http://www.scopus.com/inward/record.url?scp=85063393176&partnerID=8YFLogxK
U2 - 10.1093/mnras/sty3430
DO - 10.1093/mnras/sty3430
M3 - Article
AN - SCOPUS:85063393176
SN - 0035-8711
VL - 484
SP - 2674
EP - 2683
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -