J/AJ/166/62 New HIRES radial velocity data for V1298 Tau (Blunt+, 2023)
Overfitting Affects the Reliability of Radial Velocity Mass Estimates of the
V1298 Tau Planets.
Blunt S., Carvalho A., David T.J., Beichman C., Zink J.K., Gaidos E.,
Behmard A., Bouma L.G., Cody D., Dai F., Foreman-Mackey D., Grunblatt S.,
Howard A.W., Kosiarek M., Knutson H.A., Rubenzahl R.A., Beard C.,
Chontos A., Giacalone S., Hirano T., Johnson M.C., Lubin J.,
Akana Murphy J.M., Petigura E.A., Van Zandt J., Weiss L.
<Astron. J., 166, 62 (2023)>
=2023AJ....166...62B 2023AJ....166...62B
ADC_Keywords: Stars, pre-main sequence; Exoplanets; Spectra, optical;
Radial velocities
Keywords: Starspots ; Radial velocity
Abstract:
Mass, radius, and age measurements of young (≲100Myr) planets have
the power to shape our understanding of planet formation. However,
young stars tend to be extremely variable in both photometry and
radial velocity (RV) measurements, which makes constraining these
properties challenging. The V1298 Tau system of four ∼0.5RJup planets
transiting a pre-main-sequence star presents an important, if
stress-inducing, opportunity to observe and measure directly the
properties of infant planets. Suarez Mascareno et al. published
radial-velocity-derived masses for two of the V1298-Tau planets using
a state-of-the-art Gaussian process regression framework. The
planetary densities computed from these masses were surprisingly high,
implying extremely rapid contraction after formation in tension with
most existing planet-formation theories. In an effort to constrain
further the masses of the V1298-Tau planets, we obtained 36 RVs using
Keck/HIRES, and analyzed them in concert with published RVs and
photometry. Through performing a suite of cross-validation tests, we
found evidence that the preferred model of Suarez Mascareno et al.
suffers from overfitting, defined as the inability to predict unseen
data, rendering the masses unreliable. We detail several potential
causes of this overfitting, many of which may be important for other
RV analyses of other active stars, and recommend that additional time
and resources be allocated to understanding and mitigating activity in
active young stars such as V1298-Tau.
Description:
Between 2018 November 16 and 2020 February 6, we obtained 36 RVs using
the HIRES spectrograph on the Keck I telescope (R∼60000 at 500-620nm).
Objects:
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RA (2000) DE Designation(s)
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04 05 19.59 +20 09 25.5 V1298 Tau = 1RXS J040518.6+200919
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 23 36 New HIRES radial velocity data
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See also:
J/AJ/121/3160 : JHK photometry near the Trapezium region (Carpenter+, 2001)
J/other/Sci/330.653 : Detected planets in the Eta-Earth Survey (Howard+, 2010)
J/ApJ/790/146 : Planets in Kepler multi-transiting systems (Fabrycky+, 2014)
J/ApJ/830/46 : Radial velocities 3 Neptunemass planet hosts (Fulton+, 2016)
J/AJ/152/204 : HARPS-N radial velocities of HD179070 (Lopez-Morales+, 2016)
J/AJ/154/226 : Photometry and radial velocities of K2-131 (Dai+, 2017)
J/MNRAS/472/1618 : Kepler study of starspot lifetimes (Giles+, 2017)
J/AJ/158/58 : Autoregressive planet search Kepler stars (Caceres+, 2019)
J/ApJ/871/187 : Spot parameters on KIC solar-type stars (Namekata+, 2019)
J/AJ/159/2 : K219b & c transit time & radial velocities (Petigura+, 2020)
J/AJ/163/121 : Radial velocity & light curve of Kepler 1627A (Bouma+, 2022)
J/AJ/163/247 : HIRES, PEPSI & TRES RVel of V1298 Tau (Johnson+, 2022)
J/AJ/163/156 : THYME. VI. TOI-1227 radial velocity (Mann+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 d BJD [1438/1886] Barycentric Julian Date at TDB;
BDJ-2457000 (1)
11- 17 F7.2 m/s RVel [-260/388] Radial Velocity
19- 23 F5.2 m/s e_RVel [7/20] Uncertainty in RVel
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Note (1): Some of these data were previously published in
Johnson+, 2022AJ....163..247J 2022AJ....163..247J.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 09-Feb-2024