J/AJ/170/15 Rotation periods of 272 stars from TESS & ZTF (Hattori+, 2025)
Measuring long stellar rotation periods (>10 days) from TESS FFI light curves is
possible: An investigation using TESS and ZTF.
Hattori S., Angus R., Foreman-Mackey D., Lu Y.(., Colman I.
<Astron. J., 170, 15 (2025)>
=2025AJ....170...15H 2025AJ....170...15H
ADC_Keywords: Photometry; Optical; Stars, dwarfs; Stars, K-type; Stars, M-type
Keywords: Stellar rotation ; M dwarf stars ; K dwarf stars ; Dwarf stars ;
Sky surveys ; Lomb-Scargle periodogram ; Light curves ;
Astronomy data analysis
Abstract:
The rotation period of a star is an important quantity that provides
insight into its structure and state. For stars with surface features
like starspots, their periods can be inferred from brightness
variations as these features move across the stellar surface. TESS,
with its all-sky coverage, is providing the largest sample of stars
for obtaining rotation periods. However, most of the periods have been
limited to shorter than the 13.7days TESS orbital period due to strong
background signals (e.g., scattered light) on those timescales. In
this study, we investigated the viability of measuring longer periods
(>10days) from TESS light curves for stars in the Northern Continuous
Viewing Zone (NCVZ). We first created a reference set of 272 period
measurements longer than 10 days for K and M dwarfs in the NCVZ using
data from the Zwicky Transient Facility (ZTF) that we consider as the
"ground truth" given ZTF's long temporal baseline of 6+years. We then
used the unpopular pipeline to detrend TESS light curves and
implemented a modified Lomb-Scargle (LS) periodogram that accounts for
flux offsets between observing sectors. For 179 out of the 272 sources
(66%), the TESS-derived periods match the ZTF-derived periods to
within 10%. The match rate increases to 81% (137 out of 170) when
restricting to sources with a TESS LS power that exceeds a threshold.
Our results confirm the capability of measuring periods longer than
10days from TESS data, highlighting the data set's potential for
studying slow rotators.
Description:
The Zwicky Transient Facility (ZTF) is a ground-based 48inch optical
telescope located at the Palomar Observatory, California, US. With its
extremely wide 47deg2 field of view (FOV), ZTF is able to survey the
entire northern sky every two days in ZTF-r (∼410-550nm) and ZTF-g
(∼560-730nm). As ZTF had started observing in 2018 March, it has
already observed and released measurements spanning over 6 yr of the
northern night sky.
The Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey
with a 24°x96° FOV, an angular resolution of 21", and a
bandpass spanning 600-1000nm that continuously observes a strip of the
night sky for ∼27d (i.e., TESS observing sector) at a time. During the
2yr primary mission, the southern hemisphere was observed from sectors
1 to 13 (Cycle 1) while the northern hemisphere was covered from
sectors 14 to 26 (Cycle 2) with Full Frame Images (FFIs) at 30min
cadence.
As the sources for this study must have both ZTF observations and
multiple sectors of TESS observations, we started by first selecting a
sample of stars in the TESS NCVZ, a 24°-diameter circular region
centered at the northern ecliptic pole where TESS continuously
observed for ∼1yr during its second year. We restricted the sample
to K and M dwarfs as those have a higher chance of exhibiting slow
brightness variations (i.e., long periods).
This initial query returned 9612 sources. We then obtained Gaia
information of these sources by querying the Gaia DR3 (I/355) source
table and removed sources with RUWE>1.4. This RUWE cut left us with
7804 sources. We then downloaded the r-band and g-band light curves
from ZTF DR22 which contains measurements from 2018 March 17 until
2024 June 30. Fairly restrictive cuts based on criteria in the r-band
light curves leave us with a sample of 272 sources.
For each of the 272 sources with a measured ZTF r-band light curve
rotation period longer than 10d, we downloaded the TESS Cycle 2 FFI
data based on the Gaia DR2 (I/345) positions as the TESS Candidate
Target List (CTL), a subset of the TESS Input Catalog (IV/39), is
created with DR2 positions. We checked the Gaia designations to ensure
the correct source positions between DR2 and DR3 were used.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 193 272 ZTF and TESS periods for the 272 sources in this work
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See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
J/A+A/275/101 : Chemical evolution of the galactic disk I. (Edvardsson+ 1993)
J/A+A/530/A138 : Geneva-Copenhagen survey re-analysis (Casagrande+, 2011)
J/ApJ/743/48 : Stars with rotation periods & X-ray luminosities (Wright+, 2011)
J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)
J/MNRAS/472/1618 : Kepler study of starspot lifetimes (Giles+, 2017)
J/AJ/155/180 : A catalog of cool dwarf targets for the TESS (Muirhead+, 2018)
J/AJ/156/102 : The TESS Input Catalog & Candidate Target List (Stassun+, 2018)
J/ApJS/244/21 : Surface rotation & activity of Kepler stars. I. (Santos+, 2019)
J/ApJS/250/20 : Rot. periods in TESS objects of interest (TOIs) (Canto+, 2020)
J/ApJS/249/18 : The ZTF catalog of periodic variable stars (Chen+, 2020)
J/ApJ/903/99 : Stellar spins in the open cluster NGC 2516 (Healy+, 2020)
J/ApJS/255/17 : Surface rot. & activity for Kepler stars. II. (Santos+, 2021)
J/AJ/164/137 : Untangling the Gal. IV. ∼100000 stars with TESS (Kounkel+, 2022)
J/AJ/164/251 : ZTF measured rot. period of 40553 M- or G-dwarfs (Lu+, 2022)
J/ApJS/268/4 : Stellar variab. with TESS 2min cadence phot. (Fetherolf+, 2023)
J/AJ/167/189 : Rotation period for 10909 TESS targets (Colman+, 2024)
http://irsa.ipac.caltech.edu/Missions/ztf.html : ZTF archive
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- TIC [160551437/462637035] TESS Input Catalog
(IV/39) identifier
11- 29 I19 --- GaiaDR2 Gaia DR2 (I/345) source identifier
31- 46 F16.12 deg RAG2deg Gaia DR2 (I/345) right ascension (J2000);
used in TESS Input Catalog (IV/39)
48- 63 F16.13 deg DEG2deg Gaia DR2 (I/345) declination (J2000); used
in TESS Input Catalog (IV/39)
65- 82 F18.14 deg RAdeg Gaia DR3 (I/355) right ascension (ICRS) at
at Ep=2016.0
84- 101 F18.15 deg DEdeg Gaia DR3 (I/355) declination (ICRS) at
Ep=2016.0
103- 109 F7.4 mag Tmag [11.9/15] TESS magnitude
111- 120 F10.8 mag e_Tmag [6e-3/0.02] TESS magnitude error
122- 139 F18.15 mag Gmag [13/16] Gaia G-band mean magnitude
141- 146 F6.1 K Teff [2899/5278] Effective temperature from TESS
Input Catalog (IV/39)
148- 154 F7.3 K e_Teff [121.1/158.4] Teff error
156- 173 F18.15 d Prot-ZTF-r [10/99.6] ZTF r-band rotation period
175- 193 F19.16 d Prot-TESS [0.5/97.1] TESS rotation period
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 25-Mar-2026