_version_ 1866918159624175616
author O'Brien, Sean M.
Schwamb, Megan E.
Watson, Christopher A.
Nielsen, Louise D.
Bryant, Edward M.
Casewell, Sarah L.
Burleigh, Matthew R.
Fortson, Lucy
Gill, Samuel
Lintott, Chris J.
Hobbs, Katlyn L.
Apergis, Ioannis
Bayliss, Daniel
Fernández, Jorge Fernández
Günther, Maximilian N.
Hawthorn, Faith
Jenkins, James S.
Kendall, Alicia
McCormac, James
de Mooij, Ernst J. W.
Rodel, Toby
Saha, Suman
Trouille, Laura
West, Richard G.
Wheatley, Peter J.
Agafitei, Marius Constantin
Apaydın, Deniz Rüzgar
Baeten, Elisabeth
Baller, Bruce
Carabott, Jeff
Chesson, Sallyann
Freigeiro, Sebastián Alejandro
Gonano, Virgilio
Hanke, Matthias
Hermes, Pete
Hildebrand, Avery
Langley, John S.
Lim, See Min
McCarthy, Leo Ryan
Mitchell, Graham
O'Neill, Ken
Pearson, Charles R.
Reket, Nolan
Riethmiller, Jeanne
Saeftel, Juergen
Sainio, Arttu
Steiner, Charlie
Strickland, Amanda
Tanner, Christopher
Terentev, Ivan A.
Tiu, Ernest Jude P.
Tumanov, Sergey Y.
Urszula, Marciniak
Vahlenkamp, Pia
de Vroome, Femke
Wantuch, Paweł
Woodruff, Timothy
author_facet O'Brien, Sean M.
Schwamb, Megan E.
Watson, Christopher A.
Nielsen, Louise D.
Bryant, Edward M.
Casewell, Sarah L.
Burleigh, Matthew R.
Fortson, Lucy
Gill, Samuel
Lintott, Chris J.
Hobbs, Katlyn L.
Apergis, Ioannis
Bayliss, Daniel
Fernández, Jorge Fernández
Günther, Maximilian N.
Hawthorn, Faith
Jenkins, James S.
Kendall, Alicia
McCormac, James
de Mooij, Ernst J. W.
Rodel, Toby
Saha, Suman
Trouille, Laura
West, Richard G.
Wheatley, Peter J.
Agafitei, Marius Constantin
Apaydın, Deniz Rüzgar
Baeten, Elisabeth
Baller, Bruce
Carabott, Jeff
Chesson, Sallyann
Freigeiro, Sebastián Alejandro
Gonano, Virgilio
Hanke, Matthias
Hermes, Pete
Hildebrand, Avery
Langley, John S.
Lim, See Min
McCarthy, Leo Ryan
Mitchell, Graham
O'Neill, Ken
Pearson, Charles R.
Reket, Nolan
Riethmiller, Jeanne
Saeftel, Juergen
Sainio, Arttu
Steiner, Charlie
Strickland, Amanda
Tanner, Christopher
Terentev, Ivan A.
Tiu, Ernest Jude P.
Tumanov, Sergey Y.
Urszula, Marciniak
Vahlenkamp, Pia
de Vroome, Femke
Wantuch, Paweł
Woodruff, Timothy
contents We report the identification and characterization of a new binary system composed of two near-equal mass M-dwarfs. The binary NGTS-EB-8 was identified as a planet candidate in data from the Next Generation Transit Survey (NGTS) by citizen scientists participating in the Planet Hunters NGTS project. High-resolution spectroscopic observations reveal the system to be a double-lined binary. By modeling the photometric and radial velocity observations, we determine an orbital period of 4.2 days and the masses and radii of both stars to be $M_A=0.250^{+0.005}_{-0.004}$ M$_{\odot}$, $M_B=0.208^{+0.005}_{-0.004}$ M$_{\odot}$, $R_A=0.255^{+0.004}_{-0.005}$ R$_{\odot}$, $R_B=0.233^{+0.006}_{-0.005}$ R$_{\odot}$. We detect Balmer line emission from at least one of the stars but no significant flare activity. We note that both components lie in the fully convective regime of low-mass stars ($<0.35$ M$_{\odot}$), therefore can be a valuable test for stellar evolutionary models. We demonstrate that the photometric observations, speckle imaging and initial radial velocity measurements were unable to identify the true nature of this system and highlight that high-resolution spectroscopic observations are crucial in determining whether systems such as this are in fact binaries.
format Preprint
id arxiv_https___arxiv_org_abs_2510_11575
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle NGTS-EB-8: A double-lined eclipsing M+M binary discovered by citizen scientists
O'Brien, Sean M.
Schwamb, Megan E.
Watson, Christopher A.
Nielsen, Louise D.
Bryant, Edward M.
Casewell, Sarah L.
Burleigh, Matthew R.
Fortson, Lucy
Gill, Samuel
Lintott, Chris J.
Hobbs, Katlyn L.
Apergis, Ioannis
Bayliss, Daniel
Fernández, Jorge Fernández
Günther, Maximilian N.
Hawthorn, Faith
Jenkins, James S.
Kendall, Alicia
McCormac, James
de Mooij, Ernst J. W.
Rodel, Toby
Saha, Suman
Trouille, Laura
West, Richard G.
Wheatley, Peter J.
Agafitei, Marius Constantin
Apaydın, Deniz Rüzgar
Baeten, Elisabeth
Baller, Bruce
Carabott, Jeff
Chesson, Sallyann
Freigeiro, Sebastián Alejandro
Gonano, Virgilio
Hanke, Matthias
Hermes, Pete
Hildebrand, Avery
Langley, John S.
Lim, See Min
McCarthy, Leo Ryan
Mitchell, Graham
O'Neill, Ken
Pearson, Charles R.
Reket, Nolan
Riethmiller, Jeanne
Saeftel, Juergen
Sainio, Arttu
Steiner, Charlie
Strickland, Amanda
Tanner, Christopher
Terentev, Ivan A.
Tiu, Ernest Jude P.
Tumanov, Sergey Y.
Urszula, Marciniak
Vahlenkamp, Pia
de Vroome, Femke
Wantuch, Paweł
Woodruff, Timothy
Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
We report the identification and characterization of a new binary system composed of two near-equal mass M-dwarfs. The binary NGTS-EB-8 was identified as a planet candidate in data from the Next Generation Transit Survey (NGTS) by citizen scientists participating in the Planet Hunters NGTS project. High-resolution spectroscopic observations reveal the system to be a double-lined binary. By modeling the photometric and radial velocity observations, we determine an orbital period of 4.2 days and the masses and radii of both stars to be $M_A=0.250^{+0.005}_{-0.004}$ M$_{\odot}$, $M_B=0.208^{+0.005}_{-0.004}$ M$_{\odot}$, $R_A=0.255^{+0.004}_{-0.005}$ R$_{\odot}$, $R_B=0.233^{+0.006}_{-0.005}$ R$_{\odot}$. We detect Balmer line emission from at least one of the stars but no significant flare activity. We note that both components lie in the fully convective regime of low-mass stars ($<0.35$ M$_{\odot}$), therefore can be a valuable test for stellar evolutionary models. We demonstrate that the photometric observations, speckle imaging and initial radial velocity measurements were unable to identify the true nature of this system and highlight that high-resolution spectroscopic observations are crucial in determining whether systems such as this are in fact binaries.
title NGTS-EB-8: A double-lined eclipsing M+M binary discovered by citizen scientists
topic Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
url https://arxiv.org/abs/2510.11575