J/A+A/693/A54 GPIES survey re-reduction of 400 stars (Squicciarini+, 2025)
The COBREX archival survey: Improved constraints on the occurrence rate of
wide-orbit substellar companions.
I. A uniform re-analysis of 400 stars from the GPIES survey.
Squicciarini V., Mazoyer J., Lagrange A.-M., Chomez A., Delorme P.,
Flasseur O., Kiefer F., Bergeon S., Albert D., Meunier N.
<Astron. Astrophys. 693, A54 (2025)>
=2025A&A...693A..54S 2025A&A...693A..54S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Stars, ages ;
Stars, masses ; Parallaxes, trigonometric
Keywords: planets and satellites: detection -
planets and satellites: gaseous planets - brown dwarfs -
planetary systems - techniques: high angular resolution
Abstract:
Direct imaging (DI) campaigns are uniquely suited to probing the outer
regions around young stars and looking for giant exoplanet and brown
dwarf companions, hence providing key complementary information to
radial velocity (RV) and transit searches for the purpose of
demographic studies. However, the critical 5-20au region, where most
giant planets are thought to form, remains poorly explored, lying
in-between RV and DI capabilities. Significant gains in detection
performances can be attained at no instrumental cost by means of
advanced post-processing techniques. In the context of the COBREX
project, we have assembled the largest collection of archival DI
observations to date in order to undertake a large and uniform
re-analysis. In particular, this paper details the re-analysis of 400
stars from the GPIES survey operated at GPI@Gemini South. Following
the pre-reduction of raw frames, GPI data cubes were processed by
means of the PACO algorithm. Candidates were identified and vetted
based on multi-epoch proper motion analysis -- whenever possible --
and by means of a suitable color-magnitude diagram. The conversion of
detection limits into detectability maps allowed for an estimate of
unbiased occurrence frequencies of giant planets and brown dwarfs.
Deeper detection limits were derived compared to the literature, with
up to a twofold gain in minimum detectable mass compared to previous
GPI-based publications. Although no new substellar companion was
confirmed, we identified two interesting planet candidates awaiting
follow-up observations. We derive an occurrence rate of
1.7-0.7+0.9% for 5mjup<m<13mjup planets in 10au<a<100au, that
raises to 2.2-0.8+1.0% when including substellar objects up to
80mjup. Our results are in line with the literature, but come with
lower uncertainties thanks to the enhanced detection sensitivity. We
confirm the finding, hinted at by previous studies, of a larger
occurrence of giant planets around BA hosts compared to FGK stars;
moreover, we tentatively observe a smaller occurrence of brown dwarf
companions around BA stars, although larger samples are needed to shed
light on this point. While waiting for the wealth of data expected
from future instrument and facilities, valuable information can still
be extracted from existing data. In this regard, a complete
re-analysis of SPHERE and GPI data is expected to provide the most
precise demographic constraints ever provided by imaging.
Description:
The observations considered in this work were collected between
2013 and 2020 by means of GPI at the Gemini South telescope. GPI is an
integral-field spectrograph (IFS) with low spectral resolution (∼50),
operating in the wavelength range [0.97-2.40]um. As the vast majority
of GPI observations were gathered in the H band ([1.5-1.8]um) - other
bands being mostly used for characterization purposes - we decided to
restrict our query to H-band observations.
We downloaded therefore all H-band raw frames from GPI
that are publicly available on the Gemini archive
(https://www.cadc-ccda.hia-iha.nrccnrc.gc.ca/en/ gemini/ and
https://archive.gemini.edu/) (∼30000 frames).
We present the results of a complete re-reduction of 400 stars from the
GPIES survey, one of the largest planet-hunting DI endeavors to date,
by means of an advanced post-processing algorithm named PACO.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 138 400 Stellar properties
tableb1.dat 77 49 Observing log for the observations considered
in this work
tablec1.dat 120 102 Companion candidates
tabled1.dat 107 12 Stellar companions
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- SpType Spectral type
17- 22 F6.2 mag Gmag ? G magnitude from Gaia DR3
24- 28 F5.2 mag Hmag ? H magnitude from 2MASS
30- 33 F4.2 mag E(B-V) Estimated E(B-V)
35- 39 A5 --- YMG Most likely young moving group (YMG) (1)
41- 44 F4.2 % PYMG Membership probability to most likely YMG
46- 51 F6.1 Myr Age Age
53- 56 F4.2 Msun Mass Mass
58- 59 I2 h RAh Right Ascension (J2000)
61- 62 I2 min RAm Right Ascension (J2000)
64- 70 F7.4 s RAs Right Ascension (J2000)
72 A1 --- DE- Declination sign J2000)
73- 74 I2 deg DEd Declination (J2000)
76- 77 I2 arcmin DEm Declination (J2000)
79- 84 F6.3 arcsec DEs Declination (J2000)
86-100 A15 --- Name Star name
102-107 F6.2 --- plx Parallax
109-112 F4.2 --- e_plx Parallax error
114-119 F6.1 Myr b_Age Lower age
121-126 F6.1 Myr B_Age Upper age
128-131 F4.2 Msun b_Mass Lower mass
133-136 F4.2 Msun B_Mass Upper mass
138 A1 --- f_Age Age method (2)
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Note (1): Acronyms are defined in Table A.2, as follows:
ABDMG = AB Doradus
ARG = Argus
BPMG = beta Pic MG
CAR = Carina
CARN = Carina-Near
COL = Columba
EPSC = epsilon Cha
FIELD = Field
LCC = Lower Centaurus-Crux
THA = Tucana Horologium Association
TWA = TW Hya Association
UCL = Upper Centaurus-Lupus
USCO = Upper Scorpius
VCA = Volans-Carina Ass
Note (2): Age source as follows:
G = GPIES
S = SHINE
B = BANYAN
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 5 F5.3 arcsec Seeing Average seeing
7- 11 F5.3 --- Airmass Airmass
13- 23 A11 --- Inttot Total integration time (1)
25- 29 F5.1 deg fovrot Parallactic rotation over the sequence
31- 45 A15 --- Prog Program name
47- 56 A10 --- Name Name
58- 66 A9 --- Name2 GPIES name
68- 77 A10 "date" Obs.date Observation date
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Note (1): Number of frames x number of co-added images x
Detector Integration Time per frame (s)
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 mag H2-H3 ? SPHERE H2-H3 color
9- 12 A4 --- Method Detection algorithm
14- 24 A11 --- Status Classification
26- 30 F5.3 mas Sep Separation from the primary
32- 36 F5.3 mas e_Sep Error on separation
38- 43 F6.2 deg PA Position angle
45- 48 F4.2 deg e_PA Error on position angle
50- 55 F6.2 mag H2MAG ? Absolute SPHERE H2 magnitude
57- 62 F6.2 mag E_H2MAG ? Upper error on SPHERE H2 magnitude
64- 69 F6.2 mag e_H2MAG ? Lower error on SPHERE H2 magnitude
71- 76 F6.2 mag E_H2-H3 ? Upper error on SPHERE H2-H3 color
78- 83 F6.2 mag e_H2-H3 ? Lower error on SPHERE H2-H3 color
85- 98 A14 --- Name Star name
100-104 F5.1 --- SNR ? Detection SNR
106-109 F4.1 mag DH2mag Source-to-star contrast
111-120 A10 "date" Obs.Date Observing night
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Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
11- 16 F6.2 mas Sep Separation from the primary
18- 22 F5.2 mas e_Sep Error on separation
24- 29 F6.2 deg PA Position angle
31- 34 F4.2 deg e_PA Error on position angle
36- 39 F4.1 mag DH2mag ? Source-to-star contrast
41- 44 F4.2 --- ruwe Gaia DR3 RUWE
46- 51 F6.2 mas/yr PMa ? Hipparcos-Gaia proper motion anomaly
53- 57 F5.2 mas/yr e_PMa ? Error on PMa
59- 62 F4.1 --- signiuwe Significance of RUWE
64- 68 F5.1 --- signiPMa ? Significance of PMa
70- 72 I3 Mjup MassB Companion mass
74- 78 F5.1 Mjup E_MassB ? Upper companion mass
80- 85 F6.1 Mjup e_MassB ? Lower companion mass
87- 90 A4 --- r_Obs.Date Reference for observation (1)
92 A1 --- l_DH2mag [AC] Note on contrast (2)
94 A1 --- l_MassB [B] Note on Mass (3)
96 A1 --- Confirmed [Y/N] Companion confirmed?
98-107 A10 "date" Obs.Date Observing night
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Note (1): Reference of observation as follows:
TW = this work
W23a = Waisberg et al. (2023RNAAS...7..125W 2023RNAAS...7..125W)
W23b = Waisberg et al. (2023RNAAS...7...78W 2023RNAAS...7...78W)
B22 = Bonavita et al. (2022A&A...663A.144B 2022A&A...663A.144B, Cat. J/A+A/663/A144)
R13 = Rameau et al. (2013A%26A...553A..60R)
Note (2): Notes on contrast as follows:
A = noADI contrast, upper limit
C = upper limit
Note (3): Notes on mass as follows:
B = lower limit
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Acknowledgements:
Vito Squicciarini, vito.squicciarini(at)obspm.fr
(End) Vito Squicciarini [LESIA, Obs. Paris], Patricia Vannier [CDS] 14-Nov-2024