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Stellar Activity and its Implications for Exoplanet Detection on GJ 176

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Paper breakdownThe authors' claims, conditions and measurements, as JSON Signed receiptProof this review has not been altered
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Paul Robertson (1, 2, 3), Michael Endl (3), Gregory W. Henry (4), William D. Cochran (3), Phillip J. MacQueen (3), Michael H. Williamson (4) ((1) Department of Astronomy
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Astrophysics, The Pennsylvania State University, (2) Center for Exoplanets & Habitable Worlds, (3) Department of Astronomy, McDonald Observatory, University of Texas at Austin, (4) Center of Excellence in Information Systems, Tennessee State University)

Solar and Stellar Astrophysics · Submitted 12 Jan 2015

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim The sodium index is well correlated with our RVs, and we show that this activity trend drives a corresponding slope in RV.

how it is stated · asserted 1.00 read the record →

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arXiv ID1501.02807 (version 1)
Pith ID3PJJG33V, Pith's permanent record of this paper and its review
Citation2, (2) Center for Exoplanets & Habitable Worlds, 3), (3) Department of Astronomy, (4) Center of Excellence in Information Systems, Astrophysics, Gregory W. Henry (4), McDonald Observatory, Michael Endl (3), Michael H. Williamson (4) ((1) Department of Astronomy, Paul Robertson (1, Phillip J. MacQueen (3), Tennessee State University), The Pennsylvania State University, University of Texas at Austin, William D. Cochran (3). "Stellar Activity and its Implications for Exoplanet Detection on GJ 176." arXiv:1501.02807 (2015). https://pith.science/paper/3PJJG33V
Claim paper

The compiled record

The paper's own sentences, arranged. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

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Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 7,674 input tokens, $0.0003 reported.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.46 · human participants 0.01 · controlled comparison 0.05 · randomized assignment 0.01 · states quantitative result 0.84 · compares with prior results 0.80 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

We present an in-depth analysis of stellar activity and its effects on radial velocity (RV) for the M2 dwarf GJ 176 based on spectra taken over 10 years from the High Resolution Spectrograph on the Hobby-Eberly Telescope. These data are supplemented with spectra from previous observations with the HIRES and HARPS spectrographs, and V- and R-band photometry taken over 6 years at the Dyer and Fairborn observatories. Previous studies of GJ 176 revealed a super-Earth exoplanet in an 8.8-day orbit. However, the velocities of this star are also known to be contaminated by activity, particularly at the 39-day stellar rotation period. We have examined the magnetic activity of GJ 176 using the sodium I D lines, which have been shown to be a sensitive activity tracer in cool stars. In addition to rotational modulation, we see evidence of a long-term trend in our Na I D index, which may be part of a long-period activity cycle. The sodium index is well correlated with our RVs, and we show that this activity trend drives a corresponding slope in RV. Interestingly, the rotation signal remains in phase in photometry, but not in the spectral activity indicators. We interpret this phenomenon as the result of one or more large spot complexes or active regions which dominate the photometric variability, while the spectral indices are driven by the overall magnetic activity across the stellar surface. In light of these results, we discuss the potential for correcting activity signals in the RVs of M dwarfs.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We present an in-depth analysis of stellar activity and its effects on radial velocity (RV) for the M2 dwarf GJ 176 based on spectra taken over 10 years from the High Resolution Spectrograph on the Hobby-Eberly Telescope. contribution 0.99 0.96 0.04 asserted 0.98
s1 These data are supplemented with spectra from previous observations with the HIRES and HARPS spectrographs, and V- and R-band photometry taken over 6 years at the Dyer and Fairborn observatories. method 0.99 0.67 0.02 asserted 0.99
s2 Previous studies of GJ 176 revealed a super-Earth exoplanet in an 8.8-day orbit. background 1.00 0.03 0.02 asserted 1.00
s3 However, the velocities of this star are also known to be contaminated by activity, particularly at the 39-day stellar rotation period. background 1.00 0.07 0.05 asserted 0.99
s4 We have examined the magnetic activity of GJ 176 using the sodium I D lines, which have been shown to be a sensitive activity tracer in cool stars. method 0.82 0.88 0.03 asserted 1.00
s5 In addition to rotational modulation, we see evidence of a long-term trend in our Na I D index, which may be part of a long-period activity cycle. result 1.00 0.95 0.08 hedged possibility 0.88
s6 The sodium index is well correlated with our RVs, and we show that this activity trend drives a corresponding slope in RV. result 1.00 0.94 0.28 asserted 1.00
s7 Interestingly, the rotation signal remains in phase in photometry, but not in the spectral activity indicators. result 1.00 0.91 0.07 asserted 1.00
s8 We interpret this phenomenon as the result of one or more large spot complexes or active regions which dominate the photometric variability, while the spectral indices are driven by the overall magnetic activity across the stellar surface. interpretation 1.00 0.75 0.18 asserted 0.49
s9 In light of these results, we discuss the potential for correcting activity signals in the RVs of M dwarfs. future work 0.79 0.34 0.13 unclear 0.61

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 0.54.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper
Original abstract

We present an in-depth analysis of stellar activity and its effects on radial velocity (RV) for the M2 dwarf GJ 176 based on spectra taken over 10 years from the High Resolution Spectrograph on the Hobby-Eberly Telescope. These data are supplemented with spectra from previous observations with the HIRES and HARPS spectrographs, and V- and R-band photometry taken over 6 years at the Dyer and Fairborn observatories. Previous studies of GJ 176 revealed a super-Earth exoplanet in an 8.8-day orbit. However, the velocities of this star are also known to be contaminated by activity, particularly at the 39-day stellar rotation period. We have examined the magnetic activity of GJ 176 using the sodium I D lines, which have been shown to be a sensitive activity tracer in cool stars. In addition to rotational modulation, we see evidence of a long-term trend in our Na I D index, which may be part of a long-period activity cycle. The sodium index is well correlated with our RVs, and we show that this activity trend drives a corresponding slope in RV. Interestingly, the rotation signal remains in phase in photometry, but not in the spectral activity indicators. We interpret this phenomenon as the result of one or more large spot complexes or active regions which dominate the photometric variability, while the spectral indices are driven by the overall magnetic activity across the stellar surface. In light of these results, we discuss the potential for correcting activity signals in the RVs of M dwarfs.

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