75 research outputs found
Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultra-Narrowband Photometry
Infrared observations of metastable 2S helium absorption with ground- and
space-based spectroscopy are rapidly maturing, as this species is a unique
probe of exoplanet atmospheres. Specifically, the transit depth in the triplet
feature (with vacuum wavelengths near 1083.3 nm) can be used to constrain the
temperature and mass loss rate of an exoplanet's upper atmosphere. Here, we
present a new photometric technique to measure metastable 2S helium
absorption using an ultra-narrowband filter (full-width at half-maximum of
0.635 nm) coupled to a beam-shaping diffuser installed in the Wide-field
Infrared Camera (WIRC) on the 200-inch Hale Telescope at Palomar Observatory.
We use telluric OH lines and a helium arc lamp to characterize refractive
effects through the filter and to confirm our understanding of the filter
transmission profile. We benchmark our new technique by observing a transit of
WASP-69b and detect an excess absorption of % (11.1),
consistent with previous measurements after considering our bandpass. Then, we
use this method to study the inflated gas giant WASP-52b and place a
95th-percentile upper limit on excess absorption in our helium bandpass of
0.47%. Using an atmospheric escape model, we constrain the mass loss rate for
WASP-69b to be
() at 7,000 K
(12,000 K). Additionally, we set an upper limit on the mass loss rate of
WASP-52b at these temperatures of
(). These results show that
ultra-narrowband photometry can reliably quantify absorption in the metastable
helium feature.Comment: 17 pages, 8 figures (figures 1 and 2 are rasterized for arXiv file
size compliance), accepted to A
Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultranarrowband Photometry
Infrared observations of metastable 2³S helium absorption with ground- and space-based spectroscopy are rapidly maturing, as this species is a unique probe of exoplanet atmospheres. Specifically, the transit depth in the triplet feature (with vacuum wavelengths near 1083.3 nm) can be used to constrain the temperature and mass-loss rate of an exoplanet's upper atmosphere. Here, we present a new photometric technique to measure metastable 23S helium absorption using an ultranarrowband filter (FWHM 0.635 nm) coupled to a beam-shaping diffuser installed in the Wide-field Infrared Camera on the 200 inch Hale Telescope at Palomar Observatory. We use telluric OH lines and a helium arc lamp to characterize refractive effects through the filter and to confirm our understanding of the filter transmission profile. We benchmark our new technique by observing a transit of WASP-69b and detect an excess absorption of 0.498% ± 0.045% (11.1σ), consistent with previous measurements after considering our bandpass. We then use this method to study the inflated gas giant WASP-52b and place a 95th percentile upper limit on excess absorption in our helium bandpass of 0.47%. Using an atmospheric escape model, we constrain the mass-loss rate for WASP-69b to be 5.25^(+0.65)_(−0.46) × 10⁻⁴ M_J/Gyr⁻¹ (3.32^(+0.67)_(−0.56) × 10⁻³ M_J/Gyr⁻¹) at 7000 K (12,000 K). Additionally, we set an upper limit on the mass-loss rate of WASP-52b at these temperatures of 2.1 × 10⁻⁴ M_J/Gyr⁻¹ (2.1×10⁻³ M_J/Gyr⁻¹) . These results show that ultranarrowband photometry can reliably quantify absorption in the metastable helium feature
Spitzer observations of SN 2014J and properties of mid-IR emission in Type Ia supernovae
SN 2014J in M82 is the closest Type Ia supernova (SN Ia) in decades. The
proximity allows for detailed studies of supernova physics and provides
insights into the circumstellar and interstellar environment. In this work we
analyze Spitzer mid-IR data of SN 2014J in the 3.6 and 4.5 {\mu}m wavelength
range, together with several other nearby and well-studied SNe Ia. We compile
the first composite mid-IR light-curve templates from our sample of SNe~Ia,
spanning the range from before peak brightness well into the nebular phase. Our
observations indicate that SNe Ia form a very homogeneous class of objects at
these wavelengths. Using the low-reddening supernovae for comparison, we
constrain possible thermal emission from circumstellar dust around the highly
reddened SN 2014J. We also study SNe 2006X and 2007le, where the presence of
matter in the circumstellar environment has been suggested. No significant
mid-IR excess is detected, allowing us to place upper limits on the amount of
pre-existing dust in the circumstellar environment. For SN 2014J, M within cm, which is insufficient
to account for the observed extinction. Similar limits are obtained for SNe
2006X and 2007le.Comment: 9 pages, 4 figures. Published in MNRA
YSE-PZ: A Transient Survey Management Platform that Empowers the Human-in-the-Loop
The modern study of astrophysical transients has been transformed by an
exponentially growing volume of data. Within the last decade, the transient
discovery rate has increased by a factor of ~20, with associated survey data,
archival data, and metadata also increasing with the number of discoveries. To
manage the data at this increased rate, we require new tools. Here we present
YSE-PZ, a transient survey management platform that ingests multiple live
streams of transient discovery alerts, identifies the host galaxies of those
transients, downloads coincident archival data, and retrieves photometry and
spectra from ongoing surveys. YSE-PZ also presents a user with a range of tools
to make and support timely and informed transient follow-up decisions. Those
subsequent observations enhance transient science and can reveal physics only
accessible with rapid follow-up observations. Rather than automating out human
interaction, YSE-PZ focuses on accelerating and enhancing human decision
making, a role we describe as empowering the human-in-the-loop. Finally, YSE-PZ
is built to be flexibly used and deployed; YSE-PZ can support multiple,
simultaneous, and independent transient collaborations through group-level data
permissions, allowing a user to view the data associated with the union of all
groups in which they are a member. YSE-PZ can be used as a local instance
installed via Docker or deployed as a service hosted in the cloud. We provide
YSE-PZ as an open-source tool for the community.Comment: 23 pages, 9 figures, submitted to PAS
The peculiar mass-loss history of SN 2014C as revealed through AMI radio observations
We present a radio light curve of supernova (SN) 2014C taken with the Arcminute Microkelvin Imager (AMI) Large Array at 15.7 GHz. Optical observations presented by Milisavljevic et al. demonstrated that SN 2014C metamorphosed from a stripped-envelope Type Ib SN into a strongly interacting Type IIn SN within 1 year. The AMI light curve clearly shows two distinct radio peaks, the second being a factor of 4 times more luminous than the first peak. This double bump morphology indicates two distinct phases of mass-loss from the progenitor star with the transition between density regimes occurring at 100-200 days. This reinforces the interpretation that SN 2014C exploded in a low density region before encountering a dense Hydrogen-rich shell of circumstellar material that was likely ejected by the progenitor prior to the explosion. The AMI flux measurements of the first light curve bump are the only reported observations taken within ∼ 50 to ∼ 125 days
post-explosion, before the blast-wave encountered the Hydrogen shell. Simplistic synchrotron self-absorption (SSA) and free-free absorption (FFA) modelling suggest that some physical properties of SN 2014C are consistent with the properties of other Type Ibc and IIn SNe. However, our single frequency data does not allow us to distinguish between these two models, which implies they are likely too simplistic to describe the complex environment surrounding this event. Lastly, we present the precise radio location of SN 2014C obtained with eMERLIN, which will be useful for future VLBI observations of the SN
Discovery of an intermediate-luminosity red transient in M51 and its likely dust-obscured, infrared-variable progenitor
We present the discovery of an optical transient (OT) in Messier 51,
designated M51 OT2019-1 (also ZTF19aadyppr, AT 2019abn, ATLAS19bzl), by the
Zwicky Transient Facility (ZTF). The OT rose over 15 days to an observed
luminosity of (), in the
luminosity gap between novae and typical supernovae (SNe). Spectra during the
outburst show a red continuum, Balmer emission with a velocity width of
km s, Ca II and [Ca II] emission, and absorption features
characteristic of an F-type supergiant. The spectra and multiband light curves
are similar to the so-called "SN impostors" and intermediate-luminosity red
transients (ILRTs). We directly identify the likely progenitor in archival
Spitzer Space Telescope imaging with a m luminosity of
and a color redder than 0.74 mag, similar
to those of the prototype ILRTs SN 2008S and NGC 300 OT2008-1. Intensive
monitoring of M51 with Spitzer further reveals evidence for variability of the
progenitor candidate at [4.5] in the years before the OT. The progenitor is not
detected in pre-outburst Hubble Space Telescope optical and near-IR images. The
optical colors during outburst combined with spectroscopic temperature
constraints imply a higher reddening of mag and higher
intrinsic luminosity of
() near peak than seen in previous ILRT
candidates. Moreover, the extinction estimate is higher on the rise than on the
plateau, suggestive of an extended phase of circumstellar dust destruction.
These results, enabled by the early discovery of M51 OT2019-1 and extensive
pre-outburst archival coverage, offer new clues about the debated origins of
ILRTs and may challenge the hypothesis that they arise from the
electron-capture induced collapse of extreme asymptotic giant branch stars.Comment: 21 pages, 5 figures, published in ApJ
SN 2022joj: A Potential Double Detonation with a Thin Helium shell
We present photometric and spectroscopic data for SN 2022joj, a nearby
peculiar Type Ia supernova (SN Ia) with a fast decline rate ( mag). SN 2022joj shows exceedingly red colors, with a value of
approximately mag during its initial stages, beginning from
days before maximum brightness. As it evolves the flux shifts towards the
blue end of the spectrum, approaching mag around maximum
light. Furthermore, at maximum light and beyond, the photometry is consistent
with that of typical SNe Ia. This unusual behavior extends to its spectral
characteristics, which initially displayed a red spectrum and later evolved to
exhibit greater consistency with typical SNe Ia. We consider two potential
explanations for this behavior: double detonation from a helium shell on a
sub-Chandrasekhar-mass white dwarf and Chandrasekhar-mass models with a shallow
distribution of . The shallow nickel models could not reproduce
the red colors in the early light curves. Spectroscopically, we find strong
agreement between SN 2022joj and double-detonation models with white dwarf
masses around 1 and thin He-shell between 0.01 and 0.02
. Moreover, the early red colors are explained by
line-blanketing absorption from iron-peak elements created by the double
detonation scenario in similar mass ranges. However, the nebular spectra
composition in SN 2022joj deviates from expectations for double detonation, as
we observe strong [Fe III] emission instead of [Ca II] lines as anticipated
from double detonation models. More detailed modeling, e.g., including viewing
angle effects, is required to test if double detonation models can explain the
nebular spectra
Keck Infrared Transient Survey I: Survey Description and Data Release 1
We present the Keck Infrared Transient Survey (KITS), a NASA Key Strategic
Mission Support program to obtain near-infrared (NIR) spectra of astrophysical
transients of all types, and its first data release, consisting of 105 NIR
spectra of 50 transients. Such a data set is essential as we enter a new era of
IR astronomy with the James Webb Space Telescope (JWST) and the upcoming Nancy
Grace Roman Space Telescope (Roman). NIR spectral templates will be essential
to search JWST images for stellar explosions of the first stars and to plan an
effective Roma} SN Ia cosmology survey, both key science objectives for mission
success. Between 2022 February and 2023 July, we systematically obtained 274
NIR spectra of 146 astronomical transients, representing a significant increase
in the number of available NIR spectra in the literature. The first data
release includes data from the 2022A semester. We systematically observed three
samples: a flux-limited sample that includes all transients 17 mag in a red
optical band (usually ZTF r or ATLAS o bands); a volume-limited sample
including all transients within redshift ( Mpc); and
an SN Ia sample targeting objects at phases and light-curve parameters that had
scant existing NIR data in the literature. The flux-limited sample is 39%
complete (60% excluding SNe Ia), while the volume-limited sample is 54%
complete and is 79% complete to . All completeness numbers will rise
with the inclusion of data from other telescopes in future data releases.
Transient classes observed include common Type Ia and core-collapse supernovae,
tidal disruption events (TDEs), luminous red novae, and the newly categorized
hydrogen-free/helium-poor interacting Type Icn supernovae. We describe our
observing procedures and data reduction using Pypeit, which requires minimal
human interaction to ensure reproducibility
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