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arXiv · 2508.05893

Absolute Parameters of Young Stars: NO Puppis

Ahmet Erdem·Volkan Bakış·John Southworth·Michael D. Rhodes·Filiz Kahraman Aliçavuş·Edwin Budding·Mark Blackford·Timothy Banks·Murray Alexander
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Abstract

The southern early-type, young, eccentric-orbit eclipsing binary NO Puppis forms the A component of the multiple star Gaia DR3 552\-8147999779517568. The B component is an astrometric binary now at a separation of about 8.1 arcsec. There may be other fainter stars in this interesting but complex stellar system. We have combined several lines of evidence, including TESS data from 4 sectors, new ground-based BVR photometry, HARPS (ESO) and HERCULES (UCMJO) high-resolution spectra and astrometry of NO Pup. We derive a revised set of absolute parameters with increased precision. Alternative optimal curve-fitting programs were used in the analysis, allowing a wider view of modelling and parameter uncertainties. The main parameters are as follows: $M_{Aa} = 3.58 \pm 0.11$, $M_{Ab} = 1.68 \pm 0.09$ (M$_\odot$); $R_{Aa} = 2.17 \pm 0.03$, $R_{Ab} = 1.51 \pm 0.06$ (R$_\odot$), and $T_{\rm e Aa} = 13300 \pm 500$, $T_{\rm e Ab} = 7400 \pm 500$ (K). We estimate approximate masses of the wide companions, Ba and Bb, as $M_{Ba} = 2.0$ and $M_{Bb} = 1.8$ (M$_\odot$). The close binary's orbital separation is $a= 8.51 \pm 0.05$ (R$_\odot$); its age is approximately $20$ Myr and distance $172 \pm 1$ pc. The close binary's secondary (Ab) appears to be the source of low amplitude $ {\delta}$ Scuti-type oscillations, although the form of these oscillations is irregular and unrepetitive. Analysis of the $ \lambda$ 6678 He I profile of the primary show synchronism of the mean bodily and orbital rotations. The retention of significant orbital eccentricity, in view of the closeness of the A-system components, is unexpected and poses challenges for the explanation that we discuss.

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Ahmet Erdem, Volkan Bakış, John Southworth, Michael D. Rhodes, Filiz Kahraman Aliçavuş, Edwin Budding, Mark Blackford, Timothy Banks, Murray Alexander. 2025-08-07. Absolute Parameters of Young Stars: NO Puppis. https://doi.org/10.1017/pasa.2025.10080

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