Improving radial velocity precision with CARMENES-PLUS

IF 2.2 3区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Experimental Astronomy Pub Date : 2025-09-01 DOI:10.1007/s10686-025-10020-0

R. Varas, R. Calvo-Ortega, P. J. Amado, S. Becerril, H. Ruh, M. Azzaro, L. Hernández, H. Magán-Madinabeitia, S. Reinhart, D. Maroto-Fernández, J. Helmling, Á. L. Huelmo, D. Benítez, J. F. López, M. Pineda, J. A. García, J. García de la Fuente, J. Marín, F. Hernández, J. Aceituno, J. A. Caballero, A. Kaminski, R. J. Mathar, A. Quirrenbach, A. Reiners, I. Ribas, W. Seifert, M. Zechmeister

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引用次数: 0

Abstract

Context: CARMENES is a dual-channel high-resolution spectrograph at the 3.5 m Calar Alto telescope designed to detect low-mass planets around late-type dwarfs by measuring their radial velocities (RVs). High thermal stability in both the visible (VIS) and near-infrared (NIR) channels is essential to achieve the precision required for these measurements. In particular, stabilising the NIR channel to the millikelvin level, which operates at cryogenic temperatures ( \(\sim\) 140 K), poses significant engineering challenges. Purpose: The CARMENES-PLUS project was initiated to improve the instrument’s intrinsic RV precision. In this article, we focus on the thermal stability improvements made to the NIR channel’s cooling system. Methods: The NIR cooling system was originally conceived to operate with a discontinuous flow of cryogenic nitrogen gas. As part of CARMENES-PLUS, this was upgraded to a continuous flow configuration. Additional changes included the installation of an automatic vacuum system, a proportional control valve, and a pressure regulation system. These upgrades were designed to reduce thermal fluctuations and enhance long-term stability. Results: The implemented upgrades significantly improved the intrinsic RV precision of the NIR channel. We quantified this improvement using Fabry-Pérot calibration spectra, obtaining an intrinsic RV precision of 0.67 m s\(^{-1}\) after the interventions, an improvement of nearly 2 m s\(^{-1}\). We also assessed the stability of the nightly zero points, finding a reduced scatter of 3.9 m s\(^{-1}\) post-upgrade, compared to 6.1 m s\(^{-1}\) before. For a sample of slowly rotating stars (\(v \sin i_\star \le\) 2 km s\(^{-1}\)), the median scatter decreased from 8.8 m s\(^{-1}\) to 6.7 m s\(^{-1}\) after the upgrades. Conclusions: These results demonstrate that the thermal control upgrades introduced in CARMENES-PLUS have enhanced the NIR channel’s RV performance, bringing it closer to the VIS channel’s stability and reinforcing CARMENES’s capabilities for exoplanet detection around M dwarfs.

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提高径向速度精度与CARMENES-PLUS

背景：CARMENES是位于3.5米Calar Alto望远镜上的双通道高分辨率光谱仪，旨在通过测量其径向速度（rv）来探测晚型矮星周围的低质量行星。在可见（VIS）和近红外（NIR）通道中的高热稳定性对于实现这些测量所需的精度至关重要。特别是，将近红外通道稳定到毫开尔文水平，在低温（\(\sim\) 140 K）下工作，带来了重大的工程挑战。目的：启动CARMENES-PLUS项目以提高仪器的内在RV精度。在这篇文章中，我们关注的是近红外通道冷却系统的热稳定性改进。方法：近红外冷却系统最初设想在不连续的低温氮气流中运行。作为CARMENES-PLUS的一部分，它被升级为连续流配置。其他变化包括安装自动真空系统，比例控制阀和压力调节系统。这些升级旨在减少热波动，提高长期稳定性。结果：改进后的近红外通道内禀RV精度显著提高。我们使用fabry - p校准光谱对这种改进进行了量化，在干预后获得了0.67 m s \(^{-1}\)的固有RV精度，提高了近2 m s \(^{-1}\)。我们还评估了夜间零点的稳定性，发现升级后的散点减少了3.9米（\(^{-1}\)），而升级前的散点减少了6.1米（\(^{-1}\)）。对于一个缓慢旋转的恒星样本（\(v \sin i_\star \le\) 2 km s \(^{-1}\)），在升级后，中位数散射从8.8 m s \(^{-1}\)下降到6.7 m s \(^{-1}\)。结论：这些结果表明，CARMENES- plus引入的热控制升级提高了近红外通道的RV性能，使其更接近VIS通道的稳定性，并增强了CARMENES探测M矮星周围系外行星的能力。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Experimental Astronomy 地学天文-天文与天体物理

CiteScore

5.30

自引率

3.30%

发文量

审稿时长

6-12 weeks

期刊介绍： Many new instruments for observing astronomical objects at a variety of wavelengths have been and are continually being developed. Furthermore, a vast amount of effort is being put into the development of new techniques for data analysis in order to cope with great streams of data collected by these instruments. Experimental Astronomy acts as a medium for the publication of papers of contemporary scientific interest on astrophysical instrumentation and methods necessary for the conduct of astronomy at all wavelength fields. Experimental Astronomy publishes full-length articles, research letters and reviews on developments in detection techniques, instruments, and data analysis and image processing techniques. Occasional special issues are published, giving an in-depth presentation of the instrumentation and/or analysis connected with specific projects, such as satellite experiments or ground-based telescopes, or of specialized techniques.