210 research outputs found
The Detection of Low Mass Companions in Hyades Cluster Spectroscopic Binary Stars
We have observed a large sample of spectroscopic binary stars in the Hyades
Cluster, using high resolution infrared spectroscopy to detect low mass
companions. We combine our double-lined infrared measurements with well
constrained orbital parameters from visible light single-lined observations to
derive dynamical mass ratios. Using these results, along with photometry and
theoretical mass-luminosity relationships, we estimate the masses of the
individual components in our binaries. In this paper we present double-lined
solutions for 25 binaries in our sample, with mass ratios from ~0.1-0.8. This
corresponds to secondary masses as small as ~0.15 Msun. We include here our
preliminary detection of the companion to vB 142, with a very small mass ratio
of q=0.06+-0.04; this indicates that the companion may be a brown dwarf. This
paper is an initial step in a program to produce distributions of mass ratio
and secondary mass for Hyades cluster binaries with a wide range of periods, in
order to better understand binary star formation. As such, our emphasis is on
measuring these distributions, not on measuring precise orbital parameters for
individual binaries.Comment: 36 pages, 8 figures, accepted for publication in The Astrophysical
Journa
Simulating the Multi-Epoch Direct Detection Technique to Isolate the Thermal Emission of the Non-Transiting Hot Jupiter HD187123B
We report the 6.5 detection of water from the hot Jupiter HD187123b
with a Keplerian orbital velocity of 53 13 km/s. This high
confidence detection is made using a multi-epoch, high resolution, cross
correlation technique, and corresponds to a planetary mass of
1.4 and an orbital inclination of 21 5.
The technique works by treating the planet/star system as a spectroscopic
binary and obtaining high signal-to-noise, high resolution observations at
multiple points across the planet's orbit to constrain the system's binary
dynamical motion. All together, seven epochs of Keck/NIRSPEC -band
observations were obtained, with five before the instrument upgrade and two
after. Using high resolution SCARLET planetary and PHOENIX stellar spectral
models, along with a line-by-line telluric absorption model, we were able to
drastically increase the confidence of the detection by running simulations
that could reproduce, and thus remove, the non-random structured noise in the
final likelihood space well. The ability to predict multi-epoch results will be
extremely useful for furthering the technique. Here, we use these simulations
to compare three different approaches to combining the cross correlations of
high resolution spectra and find that the Zucker 2003 log(L) approach is least
affected by unwanted planet/star correlation for our HD187123 data set.
Furthermore, we find that the same total S/N spread across an orbit in many,
lower S/N epochs rather than fewer, higher S/N epochs could provide a more
efficient detection. This work provides a necessary validation of multi-epoch
simulations which can be used to guide future observations and will be key to
studying the atmospheres of further separated, non-transiting exoplanets.Comment: Accepted to AJ, 14 pages, 10 figure
Detection of Water Vapor in the Thermal Spectrum of the Non-Transiting Hot Jupiter upsilon Andromedae b
The upsilon Andromedae system was the first multi-planet system discovered
orbiting a main sequence star. We describe the detection of water vapor in the
atmosphere of the innermost non-transiting gas giant ups~And~b by treating the
star-planet system as a spectroscopic binary with high-resolution, ground-based
spectroscopy. We resolve the signal of the planet's motion and break the
mass-inclination degeneracy for this non-transiting planet via deep combined
flux observations of the star and the planet. In total, seven epochs of Keck
NIRSPEC band observations, three epochs of Keck NIRSPEC short wavelength
band observations, and three epochs of Keck NIRSPEC long wavelength
band observations of the ups~And~system were obtained. We perform a multi-epoch
cross correlation of the full data set with an atmospheric model. We measure
the radial projection of the Keplerian velocity ( = 55 9 km/s), true
mass ( = 1.7 ), and orbital inclination \big(
= 24 4\big), and determine that the planet's opacity structure
is dominated by water vapor at the probed wavelengths. Dynamical simulations of
the planets in the ups~And~system with these orbital elements for ups~And~b
show that stable, long-term (100 Myr) orbital configurations exist. These
measurements will inform future studies of the stability and evolution of the
ups~And~system, as well as the atmospheric structure and composition of the hot
Jupiter.Comment: Accepted to A
A near infrared frequency comb for Y+J band astronomical spectroscopy
Radial velocity (RV) surveys supported by high precision wavelength
references (notably ThAr lamps and I2 cells) have successfully identified
hundreds of exoplanets; however, as the search for exoplanets moves to cooler,
lower mass stars, the optimum wave band for observation for these objects moves
into the near infrared (NIR) and new wavelength standards are required. To
address this need we are following up our successful deployment of an H
band(1.45-1.7{\mu}m) laser frequency comb based wavelength reference with a
comb working in the Y and J bands (0.98-1.3{\mu}m). This comb will be optimized
for use with a 50,000 resolution NIR spectrograph such as the Penn State
Habitable Zone Planet Finder. We present design and performance details of the
current Y+J band comb.Comment: Submitted to SPIE, conference proceedings 845
Ground- and Space-based Detection of the Thermal Emission Spectrum of the Transiting Hot Jupiter KELT-2Ab
We describe the detection of water vapor in the atmosphere of the transiting
hot Jupiter KELT-2Ab by treating the star-planet system as a spectroscopic
binary with high-resolution, ground-based spectroscopy. We resolve the signal
of the planet's motion with deep combined flux observations of the star and the
planet. In total, six epochs of Keck NIRSPEC -band observations were
obtained, and the full data set was subjected to a cross correlation analysis
with a grid of self-consistent atmospheric models. We measure a radial
projection of the Keplerian velocity, , of 148 7 km s,
consistent with transit measurements, and detect water vapor at 3.8. We
combine NIRSPEC -band data with IRAC secondary eclipse data to
further probe the metallicity and carbon-to-oxygen ratio of KELT-2Ab's
atmosphere. While the NIRSPEC analysis provides few extra constraints on the
data, it does provide roughly the same constraints on metallicity and
carbon-to-oxygen ratio. This bodes well for future investigations of the
atmospheres of non-transiting hot Jupiters.Comment: accepted to A
Contrast and Temperature Dependence of Multi-Epoch High-Resolution Cross-Correlation Exoplanet Spectroscopy
While high-resolution cross-correlation spectroscopy (HRCCS) techniques have proven effective at characterizing the atmospheres of transiting and non-transiting hot Jupiters, the limitations of these techniques are not well understood. We present a series of simulations of one HRCCS technique, which combines the cross-correlation functions from multiple epochs, to place temperature and contrast limits on the accessible exoplanet population for the first time. We find that planets approximately Saturn-size and larger within ∼0.2 AU of a Sun-like star are likely to be detectable with current instrumentation in the L-band, a significant expansion compared with the previously-studied population. Cooler (T_(eq) ≤ 1000 K) exoplanets are more detectable than suggested by their photometric contrast alone as a result of chemical changes which increase spectroscopic contrast. The L-band CH₄ spectrum of cooler exoplanets enables robust constraints on the atmospheric C/O ratio at T_(eq)∼900K, which have proven difficult to obtain for hot Jupiters. These results suggest that the multi-epoch approach to HRCCS can detect and characterize exoplanet atmospheres throughout the inner regions of Sun-like systems with existing high-resolution spectrographs. We find that many epochs of modest signal-to-noise (S/N_(epoch)∼1500) yield the clearest detections and constraints on C/O, emphasizing the need for high-precision near-infrared telluric correction with short integration times
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