Context. Using the Hamilton Échelle Spectrograph at Lick Observatory, we have obtained precise radial velocities (RVs) of a sample of 373 G- and K-giant stars over more than 12 yr, leading to the ...discovery of several single and multiple planetary systems. The RVs of the long-period (~53 yr) spectroscopic binary ε Cyg (HIP 102488) are found to exhibit additional regular variations with a much shorter period (~291 days). Aims. We intend to improve the orbital solution of the ε Cyg system and attempt to identify the cause of the nearly periodic shorter period variations, which might be due to an additional substellar companion. Methods. We used precise RV measurements of the K-giant star ε Cyg from Lick Observatory, in combination with a large set of RVs collected more recently with the SONG telescope, as well as archival data sets. We fit Keplerian and fully dynamical N-body models to the RVs in order to explore the properties of a previously known spectroscopic stellar companion and to investigate whether there is an additional planetary companion in the system. To search for long-term stable regions in the parameter space around the orbit of this putative planet, we ran a stability analysis using an N-body code. Furthermore, we explored the possibility of co-orbital bodies to the planet with a demodulation technique. We tested the hypothesis of ε Cyg being a hierarchical stellar triple by using a modified version of the N-body code. Alternative causes for the observed RV variations, such as stellar spots and oscillations, were examined by analyzing photometric data of the system and by comparing its properties to known variable stars with long secondary periods and heartbeat stars from the literature. Results. Our Keplerian model characterizes the orbit of the spectroscopic binary to higher precision than achieved previously, resulting in a semi-major axis of a = 15.8 AU, an eccentricity of e = 0.93, and a minimum mass of the secondary of msini = 0.265 M⊙. Additional short-period RV variations closely resemble the signal of a Jupiter-mass planet orbiting the evolved primary component with a period of 291 d, but the period and amplitude of the putative orbit change strongly over time. Furthermore, in our stability analysis of the system, no stable orbits could be found in a large region around the best fit. Both of these findings deem a planetary cause of the RV variations unlikely. Most of the investigated alternative scenarios also fail to explain the observed variability convincingly. Due to its very eccentric binary orbit, it seems possible, however, that ε Cyg could be an extreme example of a heartbeat system.
Context.
Many telescopes use an iodine (I
2
) absorption cell to measure precise radial velocities (RVs), but their data reduction pipelines are all tailored to their respective instrumental ...characteristics and not openly accessible.
Aims.
For existing and future projects dedicated to measuring precise RVs, we have created an open-source, flexible data reduction software to extract RVs from échelle spectra via the I
2
cell method. The software, called
pyodine
, is completely written in Python and has been built in a modular structure to allow for easy adaptation to different instruments.
Methods.
We present the fundamental concepts employed by
pyodine
, which build on existing I
2
reduction codes, and give an overview of the software’s structure. We adapted
pyodine
to two instruments, Hertzsprung SONG located at Teide Observatory (SONG hereafter) and the Hamilton spectrograph at Lick Observatory (Lick hereafter), and demonstrate the code’s flexibility and its performance on spectra from these facilities.
Results.
Both for SONG and Lick data, the
pyodine
results generally match the RV precision achieved by the dedicated instrument pipelines. Notably, our code reaches a precision of roughly 0.69 m s
−1
on a short-term solar time series of SONG spectra, and confirms the planet-induced RV variations of the star HIP 36616 on spectra from SONG and Lick. Using the solar spectra, we also demonstrate the capabilities of our software in extracting velocity time series from single absorption lines. A probable instrumental effect of SONG is still visible in the
pyodine
RVs, despite being a bit damped as compared to the original results.
Conclusions.
With
pyodine
we prove the feasibility of a highly precise, yet instrument-flexible I
2
reduction software, and in the future the code will be part of the dedicated data reduction pipelines for the SONG network and the Waltz telescope project in Heidelberg.
Currently, nearly all microcomponents are fabricated by micro-electronic production technologies like etching, deposition and other (photo) lithographic techniques. In this way, main emphasis has ...been put on surface micromechanics. The major challenge for the future will be the development of real three-dimensional microstructures. The main objective of the proposed research is the development of a production technology for three-dimensional micromechanical structures together with a study of the mechanical properties of these structures. Electrodischarge machining (EDM) is a versatile technique which is very well suited for machining complex microstructures. This paper starts with an overview of EDM technology, the current state-of-the-art of micro EDM, and a comparison of EDM with other micromachining technologies. Afterwards, the basic parameters for EDM of silicon are derived. It will be demonstrated that EDM of silicon is not only feasible, but also forms an interesting, powerful and complementary alternative to traditional silicon micromachining.
Context.
Using the Hamilton Échelle Spectrograph at Lick Observatory, we have obtained precise radial velocities (RVs) of a sample of 373 G- and K-giant stars over more than 12 yr, leading to the ...discovery of several single and multiple planetary systems. The RVs of the long-period (~53 yr) spectroscopic binary
ε
Cyg (HIP 102488) are found to exhibit additional regular variations with a much shorter period (~291 days).
Aims.
We intend to improve the orbital solution of the
ε
Cyg system and attempt to identify the cause of the nearly periodic shorter period variations, which might be due to an additional substellar companion.
Methods.
We used precise RV measurements of the K-giant star
ε
Cyg from Lick Observatory, in combination with a large set of RVs collected more recently with the SONG telescope, as well as archival data sets. We fit Keplerian and fully dynamical
N
-body models to the RVs in order to explore the properties of a previously known spectroscopic stellar companion and to investigate whether there is an additional planetary companion in the system. To search for long-term stable regions in the parameter space around the orbit of this putative planet, we ran a stability analysis using an
N
-body code. Furthermore, we explored the possibility of co-orbital bodies to the planet with a demodulation technique. We tested the hypothesis of
ε
Cyg being a hierarchical stellar triple by using a modified version of the
N
-body code. Alternative causes for the observed RV variations, such as stellar spots and oscillations, were examined by analyzing photometric data of the system and by comparing its properties to known variable stars with long secondary periods and heartbeat stars from the literature.
Results.
Our Keplerian model characterizes the orbit of the spectroscopic binary to higher precision than achieved previously, resulting in a semi-major axis of
a
= 15.8 AU, an eccentricity of
e
= 0.93, and a minimum mass of the secondary of
m
sin
i
= 0.265
M
⊙
. Additional short-period RV variations closely resemble the signal of a Jupiter-mass planet orbiting the evolved primary component with a period of 291 d, but the period and amplitude of the putative orbit change strongly over time. Furthermore, in our stability analysis of the system, no stable orbits could be found in a large region around the best fit. Both of these findings deem a planetary cause of the RV variations unlikely. Most of the investigated alternative scenarios also fail to explain the observed variability convincingly. Due to its very eccentric binary orbit, it seems possible, however, that
ε
Cyg could be an extreme example of a heartbeat system.
Abstract
Based on recently-taken and archival HARPS, FEROS, and HIRES radial velocities (RVs), we present evidence for a new planet orbiting the first ascent red giant star HD 33142 (with an improved ...mass estimate of M1.52 ± 0.03
M
⊙
), already known to host two planets. We confirm the Jovian-mass planets HD 33142b and c, with periods of
P
b
=
330.0
−
0.4
+
0.4
days and
P
c
=
810.2
−
4.2
+
3.8
days and minimum dynamical masses of
m
b
sin
i
=
1.26
−
0.05
+
0.05
M
Jup
and
m
c
sin
i
=
0.89
−
0.05
+
0.06
M
Jup
, respectively. Furthermore, our periodogram analysis of the precise RVs shows strong evidence for a short-period Doppler signal in the residuals of a two-planet Keplerian fit, which we interpret as a third, Saturn-mass planet with
m
d
sin
i
=
0.20
−
0.03
+
0.02
M
Jup
in a close-in orbit with an orbital period of
P
d
=
89.9
−
0.1
+
0.1
days. We study the dynamical behavior of the three-planet system configuration with an
N
-body integration scheme, finding it to be long-term stable with the planets alternating between low and moderate eccentricity episodes. We also perform
N
-body simulations, including stellar evolution and second-order dynamical effects such as planet–stellar tides and stellar mass loss on the way to the white dwarf phase. We find that planets HD 33142b, c, and d are likely to be engulfed near the tip of the red giant branch phase due to tidal migration. These results make the HD 33142 system an essential benchmark for planet population statistics of the multiple-planet systems found around evolved stars.
Abstract
We present an independent Doppler validation and dynamical orbital analysis of the two-planet system HD 107148, which was recently announced in Rosenthal et al. Our detailed analyses are ...based on literature HIRES data and newly obtained HARPS and CARMENES radial-velocity (RV) measurements as part of our survey in search for additional planets around single-planet systems. We perform a periodogram analysis of the available HIRES and HARPS precise RVs and stellar activity indicators. We do not find any apparent correlation between the RV measurements and the stellar activity indicators, thus linking the two strong periodicities to a moderately compact multiplanet system. We carry out orbital fitting analysis by testing various one- and two-planet orbital configurations and studying the posterior probability distribution of the fitted parameters. Our results solidify the existence of a Saturn-mass planet (HD 107148b, discovered first) with a period of
P
b
∼ 77.2 days and a second, eccentric (
e
c
∼ 0.4), Neptune-mass exoplanet (HD 107148c) with an orbital period of
P
c
∼ 18.3 days. Finally, we investigate the two-planet system’s long-term stability and overall orbital dynamics with the posterior distribution of our preferred orbital configuration. Our
N
-body stability simulations show that the system is long-term stable and exhibits large secular osculations in eccentricity but in no particular mean motion resonance configuration. The HD 107148 system, consisting of a solar-type main-sequence star with two giant planets in a rare configuration, features a common proper-motion white dwarf companion and is therefore a valuable target for understanding the formation and evolution of planetary systems.
For existing and future projects dedicated to measuring precise radial velocities (RVs), we have created an open-source, flexible data reduction software to extract RVs from échelle spectra via the ...iodine (I\(_2\)) absorption cell method. The software, called \(pyodine\), is completely written in Python and has been built in a modular structure to allow for easy adaptation to different instruments. We present the fundamental concepts employed by \(pyodine\), which build on existing I\(_2\) reduction codes, and give an overview of the software's structure. We adapted \(pyodine\) to two instruments, Hertzsprung SONG located at Teide Observatory (SONG hereafter) and the Hamilton spectrograph at Lick Observatory (Lick hereafter), and demonstrate the code's flexibility and its performance on spectra from these facilities. Both for SONG and Lick data, the \(pyodine\) results generally match the RV precision achieved by the dedicated instrument pipelines. Notably, our code reaches a precision of roughly \(0.69 \,m\,s^{-1}\) on a short-term solar time series of SONG spectra, and confirms the planet-induced RV variations of the star HIP~36616 on spectra from SONG and Lick. Using the solar spectra, we also demonstrate the capabilities of our software in extracting velocity time series from single absorption lines. A probable instrumental effect of SONG is still visible in the \(pyodine\) RVs, despite being a bit damped as compared to the original results. With \(pyodine\) we prove the feasibility of a highly precise, yet instrument-flexible I\(_2\) reduction software, and in the future the code will be part of the dedicated data reduction pipelines for the SONG network and the Waltz telescope project in Heidelberg.
Based on recently-taken and archival HARPS, FEROS and HIRES radial velocities (RVs), we present evidence for a new planet orbiting the first ascent red giant star HD33142 (with an improved mass ...estimate of 1.52\(\pm\)0.03 M\(_\odot\)), already known to host two planets. We confirm the Jovian mass planets HD33142 b and c with periods of \(P_{\rm b}\) = 330.0\(_{-0.4}^{+0.4}\) d and \(P_{\rm c}\) = 810.2\(_{-4.2}^{+3.8}\) d and minimum dynamical masses of \(m_{\rm b}\sin{i}\) = 1.26\(_{-0.05}^{+0.05}\) M\(_{\rm Jup}\) and \(m_{\rm c}\sin{i}\) = 0.89\(_{-0.05}^{+0.06}\) M\(_{\rm Jup}\). Furthermore, our periodogram analysis of the precise RVs shows strong evidence for a short-period Doppler signal in the residuals of a two-planet Keplerian fit, which we interpret as a third, Saturn-mass planet with \(m_\mathrm{d}\sin{i}\) = 0.20\(_{-0.03}^{+0.02}\) M\(_{\rm Jup}\) on a close-in orbit with an orbital period of \(P_{\rm d}\) =89.9\(_{-0.1}^{+0.1}\) d. We study the dynamical behavior of the three-planet system configurations with an N-body integration scheme, finding it long-term stable with the planets alternating between low and moderate eccentricities episodes. We also performed N-body simulations, including stellar evolution and second-order dynamical effects such as planet-stellar tides and stellar mass-loss on the way to the white dwarf phase. We find that planets HD33142 b, c and d are likely to be engulfed near the tip of the red giant branch phase due to tidal migration. These results make the HD33142 system an essential benchmark for the planet population statistics of the multiple-planet systems found around evolved stars.
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