_version_ 1866912182654992384
author Rodel, Toby
Watson, Christopher. A.
Ulmer-Moll, Solène
Gill, Samuel
Maxted, Pierre F. L.
Casewell, Sarah L.
Brahm, Rafael
Wilson, Thomas G
Costes, Jean C.
Eschen, Yoshi Nike Emilia
Doyle, Lauren
Freckelton, Alix V.
Alves, Douglas R.
Apergis, Ioannis
Bayliss, Daniel
Bouchy, Francois
Burleigh, Matthew R.
Dumusque, Xavier
Eberhardt, Jan
Fernández, Jorge Fernández
Gillen, Edward
Goad, Michael R.
Hawthorn, Faith
Helled, Ravit
Henning, Thomas
Hobbs, Katlyn L.
Jenkins, James S.
Jordán, Andrés
Kendall, Alicia
Lendl, Monika
McCormac, James
de Mooij, Ernst J. W.
O'Brien, Sean M.
Saha, Suman
Pinto, Marcelo Tala
Trifonov, Trifon
Udry, Stéphane
Wheatley, Peter J.
author_facet Rodel, Toby
Watson, Christopher. A.
Ulmer-Moll, Solène
Gill, Samuel
Maxted, Pierre F. L.
Casewell, Sarah L.
Brahm, Rafael
Wilson, Thomas G
Costes, Jean C.
Eschen, Yoshi Nike Emilia
Doyle, Lauren
Freckelton, Alix V.
Alves, Douglas R.
Apergis, Ioannis
Bayliss, Daniel
Bouchy, Francois
Burleigh, Matthew R.
Dumusque, Xavier
Eberhardt, Jan
Fernández, Jorge Fernández
Gillen, Edward
Goad, Michael R.
Hawthorn, Faith
Helled, Ravit
Henning, Thomas
Hobbs, Katlyn L.
Jenkins, James S.
Jordán, Andrés
Kendall, Alicia
Lendl, Monika
McCormac, James
de Mooij, Ernst J. W.
O'Brien, Sean M.
Saha, Suman
Pinto, Marcelo Tala
Trifonov, Trifon
Udry, Stéphane
Wheatley, Peter J.
contents Despite being the most common types of stars in the Galaxy, the physical properties of late M dwarfs are often poorly constrained. A trend of radius inflation compared to evolutionary models has been observed for earlier type M dwarfs in eclipsing binaries, possibly caused by magnetic activity. It is currently unclear whether this trend also extends to later type M dwarfs below the convective boundary. This makes the discovery of lower-mass, fully convective, M dwarfs in eclipsing binaries valuable for testing evolutionary models especially in longer-period binaries where tidal interaction between the primary and secondary is negligible. With this context, we present the discovery of the NGTS-EB-7 AB system, an eclipsing binary containing a late M dwarf secondary and an evolved G-type primary star. The secondary star has a radius of $0.125 \pm 0.006 R_\odot$ , a mass of $0.096 \pm 0.004 M_\odot$ and follows a highly eccentric $(e=0.71436 \pm 0.00085)$ orbit every $193.35875 \pm 0.00034$ days. This makes NGTS-EB-7 AB the third longest-period eclipsing binary system with a secondary smaller than $200 M_J$ with the mass and radius constrained to better than $5 \%$. In addition, NGTS-EB-7 is situated near the centre of the proposed LOPS2 southern field of the upcoming PLATO mission, allowing for detection of the secondary eclipse and measurement of the companion`s temperature. With its long-period and well-constrained physical properties - NGTS-EB-7 B will make a valuable addition to the sample of M dwarfs in eclipsing binaries and help in determining accurate empirical mass/radius relations for later M dwarf stars.
format Preprint
id arxiv_https___arxiv_org_abs_2501_04523
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle NGTS-EB-7, an eccentric, long-period, low-mass eclipsing binary
Rodel, Toby
Watson, Christopher. A.
Ulmer-Moll, Solène
Gill, Samuel
Maxted, Pierre F. L.
Casewell, Sarah L.
Brahm, Rafael
Wilson, Thomas G
Costes, Jean C.
Eschen, Yoshi Nike Emilia
Doyle, Lauren
Freckelton, Alix V.
Alves, Douglas R.
Apergis, Ioannis
Bayliss, Daniel
Bouchy, Francois
Burleigh, Matthew R.
Dumusque, Xavier
Eberhardt, Jan
Fernández, Jorge Fernández
Gillen, Edward
Goad, Michael R.
Hawthorn, Faith
Helled, Ravit
Henning, Thomas
Hobbs, Katlyn L.
Jenkins, James S.
Jordán, Andrés
Kendall, Alicia
Lendl, Monika
McCormac, James
de Mooij, Ernst J. W.
O'Brien, Sean M.
Saha, Suman
Pinto, Marcelo Tala
Trifonov, Trifon
Udry, Stéphane
Wheatley, Peter J.
Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
Despite being the most common types of stars in the Galaxy, the physical properties of late M dwarfs are often poorly constrained. A trend of radius inflation compared to evolutionary models has been observed for earlier type M dwarfs in eclipsing binaries, possibly caused by magnetic activity. It is currently unclear whether this trend also extends to later type M dwarfs below the convective boundary. This makes the discovery of lower-mass, fully convective, M dwarfs in eclipsing binaries valuable for testing evolutionary models especially in longer-period binaries where tidal interaction between the primary and secondary is negligible. With this context, we present the discovery of the NGTS-EB-7 AB system, an eclipsing binary containing a late M dwarf secondary and an evolved G-type primary star. The secondary star has a radius of $0.125 \pm 0.006 R_\odot$ , a mass of $0.096 \pm 0.004 M_\odot$ and follows a highly eccentric $(e=0.71436 \pm 0.00085)$ orbit every $193.35875 \pm 0.00034$ days. This makes NGTS-EB-7 AB the third longest-period eclipsing binary system with a secondary smaller than $200 M_J$ with the mass and radius constrained to better than $5 \%$. In addition, NGTS-EB-7 is situated near the centre of the proposed LOPS2 southern field of the upcoming PLATO mission, allowing for detection of the secondary eclipse and measurement of the companion`s temperature. With its long-period and well-constrained physical properties - NGTS-EB-7 B will make a valuable addition to the sample of M dwarfs in eclipsing binaries and help in determining accurate empirical mass/radius relations for later M dwarf stars.
title NGTS-EB-7, an eccentric, long-period, low-mass eclipsing binary
topic Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
url https://arxiv.org/abs/2501.04523