J/A+A/706/A179 HR 7275 PEPSI and STELLA radial velocity curves (Adebali+, 2026)
Surface image and activity-corrected orbit of the RS CVn binary HR 7275.
Disentangling activity tracers.
Adebali O., Weber M., Strassmeier K.G., Ilyin I.V., Steffen M., Kovari Zs.
<Astron. Astrophys. 706, A179 (2026)>
=2026A&A...706A.179A 2026A&A...706A.179A (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Radial velocities ; Optical
Keywords: techniques: radial velocities - stars: activity -
techniques: spectroscopic - stars: chromospheres - stars: imaging -
starspots
Abstract:
Quantifying stellar parameters and magnetic activity for cool stars in
double-lined spectroscopic binaries (SB2) is not straightforward, as
both stars contribute to the observed composite spectra and are likely
variable. Disentangled component spectra allow a detailed analysis of
a component's magnetic activity.
We aim at separating the spectra of the two stellar components of the
HR 7275 SB2 system. Our further aim is a more accurate orbital
solution by cleaning the observed radial velocities (RV) from activity
perturbations of the spotted primary ("RV jitter") and obtain a
surface image of this component.
We obtained time-series high- and ultra-high resolution optical spectra
and apply two different disentangling methods. RV residuals are
modeled with three-sine function fits. The primary's spectral-line
profiles are modeled with the Doppler imaging code $i$MAP. Magnetic
fields are measured for the primary based on least-square deconvolved
Stokes-V line profiles. Chromospheric emission is determined from the
line-cores of CaHK, CaIRT8542Å, and Balmer Halpha. Before
applying those analyses, we provide a disentangling technique to
determine the system properties more accurately.
The Doppler image of the primary shows two large cool spots of size
∼20% of the visible hemisphere plus three smaller spots, each still
∼13% in size. In total, HR 7275a exhibited an impressive spottedness
of ∼40% of its entire surface in May-June 2022. The RV is modulated by
the rotation of the primary with maximum amplitudes of 320ms and 650ms
for two different modulation behaviors during the 250d of our
observations. This jitter is primarily caused by the varying
asymmetries of the apparent disk brightness due to the cool spots. Its
removal resulted in roughly ten times higher precision of the orbital
elements. Our snapshot magnetic-field measurements reveal
phase-dependent (large-scale) surface fields between +0.6±2.0G at
phase 0.1 and -15.2±2.7G at phase 0.6, indicating a complex magnetic
morphology related to the location of the photospheric spots. We also
obtain a logarithmic lithium abundance of 0.58±0.1 for HR 7275a,
indicating considerable mixing, and 0.16+0.23-0.63 for HR 7275b,
which is an extremely low value.
Description:
Radial velocity data of the target HR 7275.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
19 08 25.78 +52 25 32.6 HR 7275 = TIC 399916610
----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 113 128 STELLA radial velocities
tablea2.dat 106 54 PEPSI radial velocities
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.8 d BJD Barycenteric Julian Date of observation
18- 37 F20.16 km/s RVA Radial Velocity of star A
39- 46 F8.4 km/s RVB Radial Velocity of star B
48- 67 F20.16 km/s RVAcor Corrected Radial Velocity of star A
69- 89 F21.18 m/s ResA Residual Radial Velocity of star A
91- 99 F9.5 --- SNR Signal to noise ratio
101-113 F13.10 km/s e_RV Radial velocity error
--------------------------------------------------------------------------------
Acknowledgements:
O. Adebali, oadebali(at)aip.de
(End) Patricia Vannier [CDS] 12-Dec-2025