{"id":1702,"date":"2021-02-05T08:09:00","date_gmt":"2021-02-05T07:09:00","guid":{"rendered":"https:\/\/pepsi.aip.de\/?p=1702"},"modified":"2022-05-23T10:07:32","modified_gmt":"2022-05-23T09:07:32","slug":"a-unicorn-in-monoceros-the-3m%e2%8a%99dark-companion-to-the-bright-nearby-red-giant-v723-mon-is-a-non-interacting-mass-gap-black-hole-candidate","status":"publish","type":"post","link":"https:\/\/pepsi.aip.de\/?p=1702","title":{"rendered":"A Unicorn in Monoceros: the 3M\u2299 dark companion to the bright, nearby red giant V723 Mon is a non-interacting, mass-gap black hole candidate"},"content":{"rendered":"\n

We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby (d<\/em>=460 pc), bright evolved red giant in a high mass function nearly circular binary (\ud835\udc43 = 59\u0095.9 d, e<\/em> approx. 0). Analyses of the stellar spectra and spectral energy distribution (SED) give \ud835\udc47eff<\/sub> =\u0096 4440 K, \ud835\udc3f = 173 \ud835\udc3fs\u2299<\/sub> and \ud835\udc45 = 22 \ud835\udc45\u2299<\/sub>. Matching these parameters to MIST evolutionary models indicates a mass of the visible giant of \ud835\udc40giant<\/sub> = 1.\u009507 +\/- 0.\u009524 \ud835\udc40\u2299<\/sub>. V723 Mon is a known variable star, previously classified as an eclipsing binary, but its All-Sky Automated Survey (ASAS), Kilodegree Extremely Little Telescope (KELT), and Transiting Exoplanet Survey Satellite (TESS) light curves are those of a nearly edge-on ellipsoidal variable. Detailed models of the light curves constrained by the period, radial velocities and stellar temperature give an inclination of \ud835\udc56 = 87\u0095 deg, a mass ratio of 0\u0095.30 +\/- 0\u0095.02, and a \u00a0companion mass of \ud835\udc40comp<\/sub> = 2.\u009591 +\/- 0\u0095.08 \ud835\udc40\u2299<\/sub>, a stellar\u00a0radius of the giant of \ud835\udc45giant<\/sub> = 23.\u00956 +\/-1.\u00950 \ud835\udc45\u2299<\/sub>, and a giant mass of \ud835\udc40giant<\/sub> = 0.\u009587 +\/-0.\u009508 \ud835\udc40\u2299<\/sub><\/span> , consistent with our other estimates. We identify a likely non-stellar, diffuse veiling component with contributions in the \ud835\udc35 and \ud835\udc49-band of ~64% and ~23%, respectively, and a luminosity of ~20 \ud835\udc3f\u2299<\/sub>. The SED and the absence of continuum eclipses imply that the companion mass must be dominated by a compact object even if the companion is a binary. We do observe eclipses of the Balmer lines when the dark companion passes behind the giant, but their velocity spreads are low compared to observed accretion disks. The X-ray luminosity of the system is \ud835\udc3fX<\/sub> = 1\u0095 x 10^30 erg\/s, corresponding to \ud835\udc3f\/\u009d\ud835\udc3fedd<\/sub> ~10^-9. The simplest explanation for the massive companion is a single compact object, most likely a black hole in the \u201cmass gap\u201d, although a double neutron star binary is possible.<\/p>\n

\"\"<\/a>
LBT\/PEPSI line profiles for the Balmer H\ud835\udefc, H\ud835\udefd, Ca I \ud835\udf066439 and Ca I \ud835\udf066463 lines (black). A model spectrum using the atmospheric parameters is shown in red. The blue lines show the velocity offset of the Balmer absorption lines (\u001812 km\/s) from the rest frame of the giant. PEPSI was used in its R=250,000 resolution mode.<\/figcaption><\/figure>\n

Read more: Jayasinghe et al. 2021, MNRAS, 504, 2577<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby (d=460 pc), bright evolved red giant in a high mass function nearly circular binary (\ud835\udc43 = 59\u0095.9 d, e approx. 0). Analyses of the stellar spectra and spectral energy distribution (SED) give … Continue reading A Unicorn in Monoceros: the 3M\u2299 dark companion to the bright, nearby red giant V723 Mon is a non-interacting, mass-gap black hole candidate<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"class_list":["post-1702","post","type-post","status-publish","format-standard","hentry","category-publications"],"_links":{"self":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/1702","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1702"}],"version-history":[{"count":11,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/1702\/revisions"}],"predecessor-version":[{"id":1935,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/1702\/revisions\/1935"}],"wp:attachment":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1702"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1702"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1702"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}