10 research outputs found
Supernovae in the Subaru Deep Field: An Initial Sample, and Type Ia Rate, out to Redshift 1.6
Large samples of high-redshift supernovae (SNe) are potentially powerful
probes of cosmic star formation, metal enrichment, and SN physics. We present
initial results from a new deep SN survey, based on re-imaging in the R, i', z'
bands, of the 0.25 deg2 Subaru Deep Field (SDF), with the 8.2-m Subaru
telescope and Suprime-Cam. In a single new epoch consisting of two nights of
observations, we have discovered 33 candidate SNe, down to a z'-band magnitude
of 26.3 (AB). We have measured the photometric redshifts of the SN host
galaxies, obtained Keck spectroscopic redshifts for 17 of the host galaxies,
and classified the SNe using the Bayesian photometric algorithm of Poznanski et
al. (2007) that relies on template matching. After correcting for biases in the
classification, 55% of our sample consists of Type Ia supernovae and 45% of
core-collapse SNe. The redshift distribution of the SNe Ia reaches z ~ 1.6,
with a median of z ~ 1.2. The core-collapse SNe reach z ~ 1.0, with a median of
z ~ 0.5. Our SN sample is comparable to the Hubble Space Telescope/GOODS sample
both in size and redshift range. The redshift distributions of the SNe in the
SDF and in GOODS are consistent, but there is a trend (which requires
confirmation using a larger sample) for more high-z SNe Ia in the SDF. This
trend is also apparent when comparing the SN Ia rates we derive to those based
on GOODS data. Our results suggest a fairly constant rate at high redshift that
could be tracking the star-formation rate. Additional epochs on this field,
already being obtained, will enlarge our SN sample to the hundreds, and
determine whether or not there is a decline in the SN Ia rate at z >~ 1.Comment: 20 pages, 8 figures, MNRAS accepte
The NEID precision radial velocity spectrometer: Commissioning of the Port Adapter
In October 2019, the NEID instrument (PI Suvrath Mahadevan, PSU) was delivered to the WIYN 3.5 m Telescope at Kitt Peak National Observatory. Commissioning began shortly after delivery, but was paused due to a COVID-19 imposed observatory shutdown in March 2020. The observatory has recently reopened and NEID commissioning has resumed. NEID is an optical (380-930 nm), fiber-fed, precision Doppler radial velocity system developed as part of the NN-EXPLORE partnership. While the spectrometer and calibration system are maintained in a highly controlled environment on the basement level of the WIYN, the NEID Port Adapter mounts directly to a bent-Cassegrain port on the telescope and is responsible for precisely and stably placing target light on the science fibers. Here we present a brief overview of the as-built Port Adapter and its sub-components. We then discuss preliminary on-sky performance compared to requirements as well as next steps as we complete commissioning
The TESS Grand Unified Hot Jupiter Survey. II. Twenty New Giant Planets
NASA's Transiting Exoplanet Survey Satellite (TESS) mission promises to
improve our understanding of hot Jupiters by providing an all-sky,
magnitude-limited sample of transiting hot Jupiters suitable for population
studies. Assembling such a sample requires confirming hundreds of planet
candidates with additional follow-up observations. Here, we present twenty hot
Jupiters that were detected using TESS data and confirmed to be planets through
photometric, spectroscopic, and imaging observations coordinated by the TESS
Follow-up Observing Program (TFOP). These twenty planets have orbital periods
shorter than 7 days and orbit relatively bright FGK stars ().
Most of the planets are comparable in mass to Jupiter, although there are four
planets with masses less than that of Saturn. TOI-3976 b, the longest period
planet in our sample ( days), may be on a moderately eccentric orbit
(), while observations of the other targets are consistent
with them being on circular orbits. We measured the projected stellar obliquity
of TOI-1937A b, a hot Jupiter on a 22.4 hour orbit with the Rossiter-McLaughlin
effect, finding the planet's orbit to be well-aligned with the stellar spin
axis (). We also investigated the possibility that
TOI-1937 is a member of the NGC 2516 open cluster, but ultimately found the
evidence for cluster membership to be ambiguous. These objects are part of a
larger effort to build a complete sample of hot Jupiters to be used for future
demographic and detailed characterization work.Comment: 67 pages, 11 tables, 13 figures, 2 figure sets. Resubmitted to ApJS
after revision
The warm Neptune GJ 3470b has a polar orbit
The warm Neptune GJ 3470b transits a nearby (d = 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two transits with the newly commissioned NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak Observatory, we model the classical RossiterâMcLaughlin effect, yielding a sky-projected obliquity of λ=98â12+15⊠and a vsini=0.85â0.33+0.27kmsâ1 . Leveraging information about the rotation period and size of the host star, our analysis yields a true obliquity of Ï=95â8+9⊠, revealing that GJ 3470b is on a polar orbit. Using radial velocities from HIRES, HARPS, and the Habitable-zone Planet Finder, we show that the data are compatible with a long-term radial velocity (RV) slope of ÎłÌ=â0.0022±0.0011msâ1dayâ1 over a baseline of 12.9 yr. If the RV slope is due to acceleration from another companion in the system, we show that such a companion is capable of explaining the polar and mildly eccentric orbit of GJ 3470b using two different secular excitation models. The existence of an outer companion can be further constrained with additional RV observations, Gaia astrometry, and future high-contrast imaging observations. Lastly, we show that tidal heating from GJ 3470bâs mild eccentricity has most likely inflated the radius of GJ 3470b by a factor of âŒ1.5â1.7, which could help account for its evaporating atmosphere
TESS Spots a Super-puff: The Remarkably Low Density of TOI-1420b
We present the discovery of TOI-1420b, an exceptionally low-density ( Ï = 0.08 ± 0.02 g cm ^â3 ) transiting planet in a P = 6.96 days orbit around a late G-dwarf star. Using transit observations from TESS, LCOGT, Observatoire PrivĂ© du Mont, Whitin, Wendelstein, OAUV, Ca lâOu, and KeplerCam, along with radial velocity observations from HARPS-N and NEID, we find that the planet has a radius of R _p = 11.9 ± 0.3 R _â and a mass of M _p = 25.1 ± 3.8 M _â . TOI-1420b is the largest known planet with a mass less than 50 M _â , indicating that it contains a sizeable envelope of hydrogen and helium. We determine TOI-1420bâs envelope mass fraction to be , suggesting that runaway gas accretion occurred when its core was at most four to five times the mass of the Earth. TOI-1420b is similar to the planet WASP-107b in mass, radius, density, and orbital period, so a comparison of these two systems may help reveal the origins of close-in low-density planets. With an atmospheric scale height of 1950 km, a transmission spectroscopy metric of 580, and a predicted RossiterâMcLaughlin amplitude of about 17 m s ^â1 , TOI-1420b is an excellent target for future atmospheric and dynamical characterization
TESS Spots a Super-puff: The Remarkably Low Density of TOI-1420b
We present the discovery of TOI-1420b, an exceptionally low-density (Ï = 0.08 ± 0.02 g cmâ3) transiting planet in a P = 6.96 days orbit around a late G-dwarf star. Using transit observations from TESS, LCOGT, Observatoire PrivĂ© du Mont, Whitin, Wendelstein, OAUV, Ca l'Ou, and KeplerCam, along with radial velocity observations from HARPS-N and NEID, we find that the planet has a radius of Rp = 11.9 ± 0.3Râ and a mass of Mp = 25.1 ± 3.8Mâ. TOI-1420b is the largest known planet with a mass less than 50Mâ, indicating that it contains a sizeable envelope of hydrogen and helium.<br/
Overview of the DESI Legacy Imaging Surveys
The DESI Legacy Imaging Surveys (http://legacysurvey.org/) are a combination of three public projects (the Dark Energy Camera Legacy Survey, the BeijingâArizona Sky Survey, and the Mayall z-band Legacy Survey) that will jointly image â14,000 deg2 of the extragalactic sky visible from the northern hemisphere in three optical bands (g, r, and z) using telescopes at the Kitt Peak National Observatory and the Cerro Tololo Inter-American Observatory. The combined survey footprint is split into two contiguous areas by the Galactic plane. The optical imaging is conducted using a unique strategy of dynamically adjusting the exposure times and pointing selection during observing that results in a survey of nearly uniform depth. In addition to calibrated images, the project is delivering a catalog, constructed by using a probabilistic inference-based approach to estimate source shapes and brightnesses. The catalog includes photometry from the grz optical bands and from four mid-infrared bands (at 3.4, 4.6, 12, and 22 ÎŒm) observed by the Wide-field Infrared Survey Explorer satellite during its full operational lifetime. The project plans two public data releases each year. All the software used to generate the catalogs is also released with the data. This paper provides an overview of the Legacy Surveys project