14 research outputs found
TOI-1452 b: SPIRou and TESS Reveal a Super-Earth in a Temperate Orbit Transiting an M4 Dwarf
Exploring the properties of exoplanets near or inside the radius valley provides insight on the transition from the rocky super-Earths to the larger, hydrogen-rich atmosphere mini-Neptunes. Here, we report the discovery of TOI-1452b, a transiting super-Earth (R-p = 1.67 +/- 0.07 R-circle times) in an 11.1 day temperate orbit (T-eq = 326 +/- 7 K) around the primary member (H = 10.0, T-eff = 3185 +/- 50 K) of a nearby visual-binary M dwarf. The transits were first detected by the Transiting Exoplanet Survey Satellite, then successfully isolated between the two 3.'' 2 companions with ground-based photometry from the Observatoire du Mont-Megantic and MuSCAT3. The planetary nature of TOI-1452b was established through high-precision velocimetry with the near-infrared SPTRou spectropolarimeter as part of the ongoing SPIRou Legacy Survey. The measured planetary mass (4.8 +/- 1.3 M-circle times) and inferred bulk density (5.6(-)(1.)(6)(+1.8) g cm(-3)) is suggestive of a rocky core surrounded by a volatile-rich envelope. More quantitatively, the mass and radius of TOI-1452b, combined with the stellar abundance of refractory elements (Fe, Mg, and Si) measured by SPTRou, is consistent with a core-mass fraction of 18% +/- 6% and a water-mass fraction of 22(-13)(+21)%. The water world candidate TOI-14521) is a prime target for future atmospheric characterization with JWST, featuring a transmission spectroscopy metric similar to other well-known temperate small planets such as LHS 1140b and K2-18 b. The system is located near Webb's northern continuous viewing zone, implying that is can be followed at almost any moment of the year
Comprehensive High-resolution Chemical Spectroscopy of Barnard's Star with SPIRou
Determination of fundamental parameters of stars impacts all fields of
astrophysics, from galaxy evolution to constraining the internal structure of
exoplanets. This paper presents a detailed spectroscopic analysis of Barnard's
star that compares an exceptionally high-quality (signal-to-noise ratio of
2500 in the band), high-resolution NIR spectrum taken with CFHT/SPIRou
to PHOENIX-ACES stellar atmosphere models. The observed spectrum shows
thousands of lines not identified in the models with a similar large number of
lines present in the model but not in the observed data. We also identify
several other caveats such as continuum mismatch, unresolved contamination and
spectral lines significantly shifted from their expected wavelengths, all of
these can be a source of bias for abundance determination. Out of
observed lines in the NIR that could be used for chemical spectroscopy, we
identify a short list of a few hundred lines that are reliable. We present a
novel method for determining the effective temperature and overall metallicity
of slowly-rotating M dwarfs that uses several groups of lines as opposed to
bulk spectral fitting methods. With this method, we infer = 3231
21 K for Barnard's star, consistent with the value of 3238 11 K
inferred from the interferometric method. We also provide abundance
measurements of 15 different elements for Barnard's star, including the
abundances of four elements (K, O, Y, Th) never reported before for this star.
This work emphasizes the need to improve current atmosphere models to fully
exploit the NIR domain for chemical spectroscopy analysis.Comment: 24 pages, 18 figures, submitted to Ap
The Maunakea Spectroscopic Explorer Book 2018
(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is
intended as a concise reference guide to all aspects of the scientific and
technical design of MSE, for the international astronomy and engineering
communities, and related agencies. The current version is a status report of
MSE's science goals and their practical implementation, following the System
Conceptual Design Review, held in January 2018. MSE is a planned 10-m class,
wide-field, optical and near-infrared facility, designed to enable
transformative science, while filling a critical missing gap in the emerging
international network of large-scale astronomical facilities. MSE is completely
dedicated to multi-object spectroscopy of samples of between thousands and
millions of astrophysical objects. It will lead the world in this arena, due to
its unique design capabilities: it will boast a large (11.25 m) aperture and
wide (1.52 sq. degree) field of view; it will have the capabilities to observe
at a wide range of spectral resolutions, from R2500 to R40,000, with massive
multiplexing (4332 spectra per exposure, with all spectral resolutions
available at all times), and an on-target observing efficiency of more than
80%. MSE will unveil the composition and dynamics of the faint Universe and is
designed to excel at precision studies of faint astrophysical phenomena. It
will also provide critical follow-up for multi-wavelength imaging surveys, such
as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field
Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation
Very Large Array.Comment: 5 chapters, 160 pages, 107 figure
A massive hot Jupiter orbiting a metal-rich early-M star discovered in the TESS full frame images
Observations and statistical studies have shown that giant planets are rare
around M dwarfs compared with Sun-like stars. The formation mechanism of these
extreme systems remains under debate for decades. With the help of the TESS
mission and ground based follow-up observations, we report the discovery of
TOI-4201b, the most massive and densest hot Jupiter around an M dwarf known so
far with a radius of and a mass of ,
about 5 times heavier than most other giant planets around M dwarfs. It also
has the highest planet-to-star mass ratio () among such
systems. The host star is an early-M dwarf with a mass of $0.61\pm0.02\
M_{\odot}0.63\pm0.02\ R_{\odot}0.52\pm 0.08$ dex). However, interior
structure modeling suggests that its planet TOI-4201b is metal-poor, which
challenges the classical core-accretion correlation of stellar-planet
metallicity, unless the planet is inflated by additional energy sources.
Building on the detection of this planet, we compare the stellar metallicity
distribution of four planetary groups: hot/warm Jupiters around G/M dwarfs. We
find that hot/warm Jupiters show a similar metallicity dependence around G-type
stars. For M dwarf host stars, the occurrence of hot Jupiters shows a much
stronger correlation with iron abundance, while warm Jupiters display a weaker
preference, indicating possible different formation histories.Comment: 21 pages, 11 figures, 4 tables, submitted to A
The Pristine Survey â VI. The first three years of medium-resolution follow-up spectroscopy of Pristine EMP star candidatesâ
We present the results of a 3-year long, medium-resolution spectroscopic campaign aimed at identifying very metal-poor stars from candidates selected with the CaHK, metallicity-sensitive Pristine survey. The catalogue consists of a total of 1007 stars, and includes 146 rediscoveries of metal-poor stars already presented in previous surveys, 707 new very metal-poor stars with [Fe/H]<â2.0â , and 95 new extremely metal-poor stars with [Fe/H]<â3.0â . We provide a spectroscopic [Fe/H] for every star in the catalogue, and [C/Fe] measurements for a subset of the stars (10% with [Fe/H]<â3 and 24% with â3<[Fe/H]<â2â ) for which a carbon determination is possible, contingent mainly on the carbon abundance, effective temperature and S/N of the stellar spectra. We find an average carbon enhancement fraction ([C/Fe] â„ +0.7) of 41 ± 4% for stars with â3<[Fe/H]<â2 and 58 ± 14% for stars with [Fe/H]<â3â , and report updated success rates for the Pristine survey of 56 % and 23 % to recover stars with [Fe/H]<â2.5 and [Fe/H]<â3â , respectively. Finally, we discuss the current status of the survey and its preparation for providing targets to upcoming multi-object spectroscopic surveys such as WEAVE
TOIâ1278 B: SPIRou Unveils a Rare Brown Dwarf Companion in Close-in Orbit around an M Dwarf
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