The first infrared portrait of a solar-like host star with debris disk: pioneering high-resolution H- and K- band spectroscopy of HD 115617 with comparative optical spectrum analysis

Abstract We present the first high-resolution near-infrared spectroscopic analysis of the solar analog HD 115617 (61 Virginis), complemented by optical spectroscopy, asteroseismology, and spectral energy distribution modeling. Using ESPRESSO and IGRINS spectra with a newly calibrated NIR line list, we derived atmospheric parameters that revealed notable differences between spectral regions: the optical analysis yielded T eff = 5500 ± 140 K, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>g</mml:mi> <mml:mo>=</mml:mo> <mml:mn>4.40</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.16</mml:mn> </mml:math> , and solar metallicity, whereas the NIR yielded T eff = 5750 ± 140 K. We tested this 250 K discrepancy using the independent line depth ratio (LDR) method for both spectra. When applied to the optical lines, LDR confirmed the cooler scale (5553 ± 73 K); for the NIR lines, it provided an intermediate temperature (5636 ± 15 K). Asteroseismic scaling with TESS data yielded a radius of 0.98 ± 0.09 R ⊙ , consistent with SED fitting and confirming the star’s main-sequence solar-like status. However, the age estimates diverged between methods, with optical and NIR analyses yielding ages of 10.97 and 8.04 Gyr, respectively. Critically, a condensation temperature analysis revealed no significant trend, confirming the star’s bulk solar-like composition and showing no chemical signature of planetary formation processes. Kinematic diagnostics place HD 115617 in the thin Galactic disk, with a birth radius of ∼5.7–8.0 kpc. Although the spectral differences may be linked to the star’s multi-planet system or debris disk, our analysis highlights the critical challenge of distinguishing such effects from methodological systematics in multi-wavelength studies. Consequently, we propose a systematic, homogeneous optical-NIR survey of solar-type stars to resolve this ambiguity, which could ultimately inform novel indirect methods for characterizing stellar environments.