JWST imaging of the closest globular clusters—I. Possible infrared excess among white dwarfs in NGC 6397

IF 1.1 4区物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS

Astronomische Nachrichten Pub Date : 2024-05-27 DOI:10.1002/asna.20240039

L. R. Bedin, D. Nardiello, M. Salaris, M. Libralato, P. Bergeron, A. J. Burgasser, D. Apai, M. Griggio, M. Scalco, J. Anderson, R. Gerasimov, A. Bellini

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Abstract

We present James Webb Space Telescope observations of the globular cluster NGC 6397 and use them to extend to infrared wavelengths the characterization of the cluster's entire white dwarf (WD) cooling sequence (CS). The data allows us to probe fundamental astrophysical WD properties and to search for evidence in their colors for (or against) the existence of ancient planetary systems. The existing archival Hubble Space Telescope imaging data obtained $\sim 18$ years ago reach ultra-deep optical magnitudes ( $V \sim 31$ ) and allow us to derive a near-perfect separation between field and cluster members. We detect an apparent split in the lower part of the WD CS of NGC 6397. The red part of the WD CS, containing about 25% of the total, exhibits significant IR-excess of up to $Δ m_{F 322 W 2} \sim 0.5$ mag. These infrared excesses require both theoretical and observational follow-ups to confirm their veracity and to ascertain their true nature.

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JWST 对最接近球状星团的成像-I.NGC 6397 中白矮星可能存在的红外线过量

我们展示了詹姆斯-韦伯太空望远镜对球状星团NGC 6397的观测数据，并利用这些数据将该星团整个白矮星（WD）冷却序列（CS）的特征描述扩展到了红外波段。通过这些数据，我们可以探测白矮星的基本天体物理特性，并从它们的颜色中寻找支持（或反对）古老行星系统存在的证据。多年前获得的现有哈勃太空望远镜成像档案数据达到了超深光学倍率（），使我们能够推导出场和星团成员之间近乎完美的分离。我们在 NGC 6397 的 WD CS 下部探测到了明显的分裂。WD CS的红色部分（约占总数的25%）表现出明显的红外过量，最高可达马格。这些红外过量需要理论和观测的跟进来证实其真实性，并确定其真实性质。

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来源期刊

Astronomische Nachrichten 地学天文-天文与天体物理

CiteScore

1.80

自引率

11.10%

发文量

审稿时长

4-8 weeks

期刊介绍： Astronomische Nachrichten, founded in 1821 by H. C. Schumacher, is the oldest astronomical journal worldwide still being published. Famous astronomical discoveries and important papers on astronomy and astrophysics published in more than 300 volumes of the journal give an outstanding representation of the progress of astronomical research over the last 180 years. Today, Astronomical Notes/ Astronomische Nachrichten publishes articles in the field of observational and theoretical astrophysics and related topics in solar-system and solar physics. Additional, papers on astronomical instrumentation ground-based and space-based as well as papers about numerical astrophysical techniques and supercomputer modelling are covered. Papers can be completed by short video sequences in the electronic version. Astronomical Notes/ Astronomische Nachrichten also publishes special issues of meeting proceedings.