159897 APOGEE Abundances from spectra with SNR<150 Virtual Observatory Resource

Authors
  1. Sun W.
  2. Chiappini C.
  3. Nepal S.
  4. Published by
    CDS
Abstract

Large spectroscopic surveys rely on automated pipelines to deliver homogeneous stellar labels; however, a substantial fraction of observations are carried out at a low signal-to-noise ratio (S/N) where label estimates become imprecise or are omitted. In APOGEE, these low-S/N spectra visits tend to sample faint and distant populations (i.e. the bulge, outer halo, and satellite systems), while still encoding recoverable chemical information. We present TwinSpecNet (TSN), a paired-learning framework that exploits APOGEE's multi-visit observing strategy: by training on empirical low- and high-S/N spectral twins of the same stars, TSN learns to suppress stochastic noise while preserving the ASPCAP label scale. TSN employs a Vision Transformer encoder with dual objectives: reconstructing high-S/N flux from low-S/N visits and predicting stellar parameters and abundances with calibrated uncertainties. TSN reduces label scatter relative to visit-level ASPCAP for S/N<60 visits. It reproduces the ASPCAP scale with residual scatters of sigma~19K in Teff, sigma~0.06dex in logg, and sigma~0.03dex in Fe/H. TSN tightens intra-cluster abundance dispersions, recovers cleaner chemical sequences in inner-disk and bulge and satellite samples, and improves C/N-based age precision for APOKASC giants from 1.70 to 1.49Gyr. By learning survey-specific noise patterns from repeated observations, TSN demonstrates how empirical paired learning can extend the chemical reach of existing spectroscopic data, providing a template that is applicable to other multi-visit surveys.

Keywords
  1. milky-way-galaxy
  2. chemical-abundances
  3. infrared-sources
Bibliographic source Bibcode
2026A&A...710A.173S
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History

2026-06-10T12:43:34Z
Resource record created
2026-06-10T11:46:20Z
Updated
2026-06-10T12:43:34Z
Created

Contact

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CDS support team
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