J/A+A/712/A30 KQ Pup radial velocities (Jadlovsky+, 2026)
Hidden massive eclipsing binaries in red supergiant systems.
The hierarchical triple system KQ Puppis and other candidates.
Jadlovsky D., Molnar L., Ercolino A., Bernini-Peron M., Merand A.,
Krticka J., Wang L., Adam R.Z., Baade D., Bayo A., Gonzalez-Tora G.,
Granzer T., Henry G/W/, Janik J., Kolar J., Kravchenko K., Langer N.,
Oskinova L.M., Pauli D., Ramachandran V., Rubio A.C., Sander A.A.C.,
Strassmeier K.G., Weber M., Wittkowski M., Brahm R., Schaffenroth V.,
Vanzi L., Skarka M.
<Astron. Astrophys. 712, A30 (2026)>
=2026A&A...712A..30J 2026A&A...712A..30J (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Radial velocities ; Optical
Keywords: techniques: interferometric - binaries: eclipsing -
stars: massive - stars: mass-loss - supergiants
Abstract:
The majority of massive stars are part of binary systems and may
interact with their companions during their evolution. This has
important consequences for systems in which one star evolves into a
red supergiant (RSG). However, not many RSGs have been found in binary
systems, and only a few have constrained orbital parameters.
We aim to better characterize and constrain the properties of some of
the known RSGs in binaries. We were inspired to do so by recent
observations where these RSGs transitioned to an earlier spectral
type, likely following a major interaction event with their
companions.
We searched the available TESS photometry for eclipsing companions. We
focused on the best candidate, the VV Cephei-type RSG binary KQ Pup,
which is made up of an RSG, KQ Pup A, and a B-type companion, KQ Pup B
and has an orbital period of 26 years. For this system, we have enough
data to constrain the system properties. We used archival photometry
and UV spectroscopy along with newly acquired optical spectra and
interferometric data from VLTI-GRAVITY.
Using TESS light curves, we discovered eclipses with a period of
17.2596d associated with KQ Pup B, making it a binary. We refer to the
two components as KQ Pup Ba and Bb. Meanwhile, the detection of the
hydrogen Brγ line with VLTI-GRAVITY enabled us to track the
orbital motion of the Ba+Bb pair relative to A and thus determine the
astrometric orbit of A+B. The dynamical masses agree with independent
estimates from asteroseismology and evolutionary models. The results
give a mass of ∼10M☉ for the RSG KQ Pup A and ∼14M☉ for
the sum of the hot components Ba+Bb. The observed properties of the
system are compatible with a coeval hierarchical triple star, where we
constrained the mass of KQ Pup Bb to be ≳1.2M☉. We determined
an orbital parallax of π=1.24+0.05-0.04mas based on the
detailed orbital model of the system, which is the first such parallax
measurement for an RSG, and the value is consistent with Gaia DR3.
KQ Pup represents a unique demonstration of mass transfer in a wide,
eccentric RSG system. The variability of Balmer emission lines and the
detection of Brγ are a strong signature of accretion to the
Ba+Bb pair near periastron. With the RSG filling its Roche lobe by
only ∼70% at periastron (φA+B∼0), the mass transfer is instead
driven by accretion from its extended atmosphere via the wind
Roche-lobe overflow. The accretion disk is formed already by
φA+B∼0.95, while TESS light curves also begin to show a
signature of occultations by the circumbinary disk, similar to young
stellar objects. Through apastron (φA+B∼0.5), Balmer emissions
weaken and indicate a decaying disk. Overall, using TESS, we
discovered that several previously assumed RSG binaries host eclipsing
inner systems, corresponding to ∼10% of all known Galactic RSG
binaries. This suggests that many of the other RSG binaries may also
be hierarchical triples.
Description:
We present the list of radial velocities used for the orbital fit
(VLTI global + RV) of the KQ Pup system (Table A.4). The table
consists of radial velocities for A and B from several available
datasets, also listing the archival measurements from Cowley
(1965ApJ...142..299C 1965ApJ...142..299C). Notes: MJD was calculated as HJD-2400000.5d.
Methods for determining the radial velocity of the A and B components
in various spectra are described in Sect. 4.5 of the paper. Data for B
include the determined RV from Hα based on the emission centroid
(ESPaDOnS) and from the interferometric fit to Brγ
(VLTI-GRAVITY). For the IUE spectra, the radial velocity was
determined from cross-correlation of an average IUE spectrum, giving a
relative velocity shift of the IUE spectra against each other.
Therefore, in the table we added the systemic velocity of 34.56km/s to
the determined shifts.
Objects:
----------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------
07 33 47.97 -14 31 26.05 KQ Pup = HR 2902
----------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea4.dat 44 214 KQ Pup system radial velocities
--------------------------------------------------------------------------------
See also:
J/A+A/258/423 : Spectrum of KQ Pup (Muratorio+ 1992)
J/A+AS/92/685 : Optical and UV Spectrum of KQ Pup (Altamore+ 1992)
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Inst Instrument/source name
10- 18 F9.3 d MJD Modified Julian date (MJD=HJD-2400000.5)
20- 25 F6.3 km/s RVA ? Radial velocity for A
27- 31 F5.3 km/s e_RVA ? Error on radial velocity for A
33- 38 F6.3 km/s RVB ? Radial velocity for B
40- 44 F5.3 km/s e_RVB ? Error on radial velocity for B
--------------------------------------------------------------------------------
Acknowledgements:
From Daniel Jadlovsky, jadlovsky(at)mail.muni.cz
Based on observations made with the Very Large Telescope
Interferometer (VLTI) at the Paranal Observatory of European Southern
Observatory (ESO). Based on data obtained with the STELLA robotic
telescopes in Tenerife, an AIP facility jointly operated by AIP and
IAC. Based on observations obtained at the Canada-France-Hawaii
Telescope (CFHT) which is operated by the National Research Council of
Canada, the Institut National des Sciences de l'Univers of the
Centre National de la Recherche Scientique of France, and the
University of Hawaii. We acknowledge the use of TESS High Level
Science Products (HLSP) produced by the Quick-Look Pipeline (QLP) at
the TESS Science Office at MIT, which are publicly available from the
Mikulski Archive for Space Telescopes (MAST). Funding for the TESS
mission is provided by NASA's Science Mission directorate. Based on
INES data from the IUE satellite.
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 07-Jul-2026