scholarly journals Getting More For Your Money: Identifying and Confirming Long-Period Planets with Kepler

2008 ◽  
Vol 4 (S253) ◽  
pp. 560-563
Author(s):  
Jennifer C. Yee ◽  
B. Scott Gaudi
Keyword(s):  
Radial Velocity ◽  
Circular Orbits ◽  
Transiting Planets ◽  
Long Period ◽  
The Masses ◽  
Better Than

AbstractKepler will monitor enough stars that it is likely to detect single transits of planets with periods longer than the mission lifetime. We show that by combining the Kepler photometry of such transits with precise radial velocity (RV) observations taken over ~3 months, and assuming circular orbits, it is possible to estimate the periods of these transiting planets to better than 20% (for planets with radii greater than that of Neptune) and the masses to within a factor of 2 (for planet masses mp ≥ MJup). We also explore the effects of eccentricity on these quantities.

scholarly journals Detection and Doppler monitoring of K2-285 (EPIC 246471491), a system of four transiting planets smaller than Neptune

2019 ◽  
Vol 623 ◽  
pp. A41 ◽  
Author(s):  
E. Palle ◽  
G. Nowak ◽  
R. Luque ◽  
D. Hidalgo ◽  
O. Barragán ◽  
...  
Keyword(s):  
Bulk Composition ◽  
Velocity Measurements ◽  
Good Test ◽  
Transiting Planets ◽  
Atmospheric Escape ◽  
Outer Planets ◽  
Upper Limits ◽  
The Masses ◽  
Better Than

Context. The Kepler extended mission, also known as K2, has provided the community with a wealth of planetary candidates that orbit stars typically much brighter than the targets of the original mission. These planet candidates are suitable for further spectroscopic follow-up and precise mass determinations, leading ultimately to the construction of empirical mass-radius diagrams. Particularly interesting is to constrain the properties of planets that are between Earth and Neptune in size, the most abundant type of planet orbiting Sun-like stars with periods of less than a few years. Aims. Among many other K2 candidates, we discovered a multi-planetary system around EPIC 246471491, referred to henceforth as K2-285, which contains four planets, ranging in size from twice the size of Earth to nearly the size of Neptune. We aim here at confirming their planetary nature and characterizing the properties of this system. Methods. We measure the mass of the planets of the K2-285 system by means of precise radial-velocity measurements using the CARMENES spectrograph and the HARPS-N spectrograph. Results. With our data we are able to determine the mass of the two inner planets of the system with a precision better than 15%, and place upper limits on the masses of the two outer planets. Conclusions. We find that K2-285b has a mass of Mb = 9.68−1.37+1.21 M⊕ and a radius of Rb = 2.59−0.06+0.06 R⊕, yielding a mean density of ρb = 3.07−0.45+0.45 g cm−3, while K2-285c has a mass of Mc = 15.68−2.13+2.28 M⊕, radius of Rc = 3.53−0.08+0.08 R⊕, and a mean density of ρc = 1.95−0.28+0.32 g cm−3. For K2-285d (Rd = 2.48−0.06+0.06 R⊕) and K2-285e (Re = 1.95−0.05+0.05 R⊕), the upper limits for the masses are 6.5 M⊕ and 10.7 M⊕, respectively. The system is thus composed of an (almost) Neptune-twin planet (in mass and radius), two sub-Neptunes with very different densities and presumably bulk composition, and a fourth planet in the outermost orbit that resides right in the middle of the super-Earth/sub-Neptune radius gap. Future comparative planetology studies of this system would provide useful insights into planetary formation, and also a good test of atmospheric escape and evolution theories.

scholarly journals Revisiting the eccentricities of hot Jupiters

2010 ◽  
Vol 6 (S276) ◽  
pp. 243-247
Author(s):  
Nawal Husnoo ◽  
Frédéric Pont ◽  
Tsevi Mazeh ◽  
Daniel Fabrycky ◽  
Guillaume Hébrard ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Circular Orbits ◽  
Hot Jupiters ◽  
Transiting Planets ◽  
Eccentric Orbits ◽  
Tidal Theory ◽  
Short Period ◽  
Formation And Evolution ◽  
Orbital Periods ◽  
Radial Velocity Data

AbstractMost short period transiting exoplanets have circular orbits, as expected from an estimation of the circularisation timescale using classical tidal theory. Interestingly, a small number of short period transiting exoplanets seem to have orbits with a small eccentricity. Such systems are valuable as they may indicate that some key physics is missing from formation and evolution models. We have analysed the results of a campaign of radial velocity measurements of known transiting planets with the SOPHIE and HARPS spectrographs using Bayesian methods and obtained new constraints on the orbital elements of 12 known transiting exoplanets. We also reanalysed the radial velocity data for another 42 transiting systems and show that some of the eccentric orbits reported in the Literature are compatible with a circular orbit. As a result, we show that the systems with circular and eccentric orbits are clearly separated on a plot of the planetary mass versus orbital period. We also show that planets following the trend where heavier hot Jupiters have shorter orbital periods (the “mass-period relation” of hot Jupiters), also tend to have circular orbits, with no confirmed exception to this rule so far.

scholarly journals A long-period (P = 61.8 d) M5V dwarf eclipsing a Sun-like star from TESS and NGTS

2020 ◽  
Vol 495 (3) ◽  
pp. 2713-2719 ◽  
Author(s):  
Samuel Gill ◽  
Benjamin F Cooke ◽  
Daniel Bayliss ◽  
Louise D Nielsen ◽  
Monika Lendl ◽  
...  
Keyword(s):  
South Africa ◽  
Radial Velocity ◽  
Stellar Evolution ◽  
Orbital Period ◽  
Next Generation ◽  
Velocity Measurements ◽  
Long Period ◽  
Better Than

ABSTRACT The Transiting Exoplanet Survey Satellite has produced a large number of single-transit event candidates which are being monitored by the Next Generation Transit Survey (NGTS). We observed a second epoch for the TIC-231005575 system (Tmag = 12.06 and $T_{\rm eff} = 5500 \pm 85\, \mathrm{ K}$) with NGTS and a third epoch with Las Cumbres Observatory’s telescope in South Africa to constrain the orbital period ($P = 61.777\, \mathrm{ d}$). Subsequent radial velocity measurements with CORALIE revealed the transiting object has a mass of M2 = 0.128 ± 0.003 M⊙, indicating the system is a G-M binary. The radius of the secondary is R2 = 0.154 ± 0.008 R⊙ and is consistent with mesa models of stellar evolution to better than 1σ.

scholarly journals Directly testing gravity with Proxima Centauri

2019 ◽  
Vol 487 (2) ◽  
pp. 1653-1661 ◽  
Author(s):  
Indranil Banik ◽  
Pavel Kroupa
Keyword(s):  
Radial Velocity ◽  
Close Binaries ◽  
Wide Binary ◽  
Design Specifications ◽  
Long Period ◽  
Decisive Test ◽  
Binary Orbit ◽  
Zero Points ◽  
Precision Astrometry ◽  
Better Than

ABSTRACT The wide binary orbit of Proxima Centauri around α Centauri A and B differs significantly between Newtonian and Milgromian dynamics (MOND). By combining previous calculations of this effect with mock observations generated using a Monte Carlo procedure, we show that this prediction can be tested using high precision astrometry of Proxima Centauri. This requires ≈10 yr of observations at an individual epoch precision of $0.5 \, \mu\rm as$, within the design specifications of the proposed Theia mission. In general, the required duration should scale as the 2/5 power of the astrometric precision. A long-period planet could produce a MOND-like astrometric signal, but only if it has a particular ratio of mass to separation squared and a sky position close to the line segment connecting Proxima Centauri with α Centauri. Uncertainties in perspective effects should be small enough for this test if the absolute radial velocity of Proxima Centauri can be measured to within ≈10 m s−1, better than the present accuracy of 32 m s−1. We expect the required improvement to become feasible using radial velocity zero-points estimated from larger samples of close binaries, with the Sun providing an anchor. We demonstrate that possible astrometric microlensing of Proxima Centauri is unlikely to affect the results. We also discuss why it should be possible to find sufficiently astrometrically stable reference stars. Adequately, addressing these and other issues would enable a decisive test of gravity in the currently little explored low acceleration regime relevant to the dynamical discrepancies in galactic outskirts.

Scheduling strategies for the ESPRESSO follow-up of TESS targets

2021 ◽  
Vol 503 (4) ◽  
pp. 5504-5521
Author(s):  
L Cabona ◽  
P T P Viana ◽  
M Landoni ◽  
J P Faria
Keyword(s):  
Radial Velocity ◽  
Planetary Systems ◽  
Data Set ◽  
Noise Component ◽  
Orbital Parameters ◽  
Transiting Planets ◽  
Accuracy And Precision ◽  
Scheduling Strategies ◽  
The Masses

ABSTRACT Radial-velocity follow-up of stars harbouring transiting planets detected by TESS is expected to require very large amounts of expensive telescope time in the next few years. Therefore, scheduling strategies should be implemented to maximize the amount of information gathered about the target planetary systems. We consider myopic and non-myopic versions of a novel uniform-in-phase scheduler, as well as a random scheduler, and compare these scheduling strategies with respect to the bias, accuracy and precision achieved in recovering the mass and orbital parameters of transiting and non-transiting planets. This comparison is carried out based on realistic simulations of radial-velocity follow-up with ESPRESSO of a sample of 50 TESS target stars, with simulated planetary systems containing at least one transiting planet with a radius below 4R⊕. Radial-velocity data sets were generated under reasonable assumptions about their noise component, including that resulting from stellar activity, and analysed using a fully Bayesian methodology. We find the random scheduler leads to a more biased, less accurate, and less precise, estimation of the mass of the transiting exoplanets. No significant differences are found between the results of the myopic and non-myopic implementations of the uniform-in-phase scheduler. With only about 22 radial velocity measurements per data set, our novel uniform-in-phase scheduler enables an unbiased (at the level of 1 per cent) measurement of the masses of the transiting planets, while keeping the average relative accuracy and precision around 16 per cent and 23 per cent, respectively. The number of non-transiting planets detected is similar for all the scheduling strategies considered, as well as the bias, accuracy and precision with which their masses and orbital parameters are recovered.

scholarly journals The TROY project: Searching for co-orbital bodies to known planets

2018 ◽  
Vol 609 ◽  
pp. A96 ◽  
Author(s):  
J. Lillo-Box ◽  
D. Barrado ◽  
P. Figueira ◽  
A. Leleu ◽  
N. C. Santos ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Planetary Systems ◽  
Occurrence Rate ◽  
Velocity Data ◽  
Transiting Planets ◽  
Extrasolar Systems ◽  
Upper Limits ◽  
And Migration ◽  
The Masses ◽  
Radial Velocity Data

Context. The detection of Earth-like planets, exocomets or Kuiper belts show that the different components found in the solar system should also be present in other planetary systems. Trojans are one of these components and can be considered fossils of the first stages in the life of planetary systems. Their detection in extrasolar systems would open a new scientific window to investigate formation and migration processes. Aims. In this context, the main goal of the TROY project is to detect exotrojans for the first time and to measure their occurrence rate (η-Trojan). In this first paper, we describe the goals and methodology of the project. Additionally, we used archival radial velocity data of 46 planetary systems to place upper limits on the mass of possible trojans and investigate the presence of co-orbital planets down to several tens of Earth masses. Methods. We used archival radial velocity data of 46 close-in (P < 5 days) transiting planets (without detected companions) with information from high-precision radial velocity instruments. We took advantage of the time of mid-transit and secondary eclipses (when available) to constrain the possible presence of additional objects co-orbiting the star along with the planet. This, together with a good phase coverage, breaks the degeneracy between a trojan planet signature and signals coming from additional planets or underestimated eccentricity. Results. We identify nine systems for which the archival data provide >1σ evidence for a mass imbalance between L4 and L5. Two of these systems provide >2σ detection, but no significant detection is found among our sample. We also report upper limits to the masses at L4/L5 in all studied systems and discuss the results in the context of previous findings.

Some of Frontiers Education Articles: Around First to Eleven December 2020

2020 ◽  
Author(s):  
thobias sarbunan
Keyword(s):  
Knowledge Creation ◽  
Publishing House ◽  
General Point ◽  
Human Race ◽  
Future Studies ◽  
Long Period ◽  
Research And Innovation ◽  
New Information ◽  
Scientific Ideas ◽  
Better Than

The research pathway is also an important point to lead researchers in creating and enriching knowledge from a fresh viewpoint, as wellas development for the human race. The frontier is the publishing house of a publication that has established information along with the'other agent' of knowledge around the globe. As a result, one of the sub-journals of this publication was education, expanded awarenesstime by time, by new information on innovation in science and technology. In the meantime, the pandemic, better than the science society,has alerted to the current developments in science aimed at strengthening and gaining some insight and awareness of how to maintainthe 'mode of knowledge creation'. So, through this discussion of the current edition of Frontier Education Journals, I thought that thisdiscussion theoretically involved encouragement and advancement in the middle of the pandemic, also influenced from a general point ofview, here as roadmap or step-stone for all research and innovation researchers. On the basis of the discussion in general, I saw that theroad map of the topic of frontier education is in significance to all branches of expertise of education. I agree that knowledge developmenttime-by-time needs to be reflected-analysed-synthesized-adopted or adapted-also developed for the purpose of education in addition tolearning from a general viewpoint. Note, knowledge is never-never sleeping tight, but it still evolves and progresses a long period with thenewest scientific ideas-concept-and hypothesis. In the other hand, it is possible that my study would miss a range of weaknesses inliteracy resources as well; but at least, I have sought, through this article, to see the importance of knowledge advancement that can enrichknowledge in the middle of the pandemic and for future studies.

scholarly journals The Mass-Luminosity Relation From Binaries

1998 ◽  
Vol 11 (1) ◽  
pp. 419-420
Author(s):  
David W. Latham
Keyword(s):  
Eclipsing Binaries ◽  
M Dwarfs ◽  
Direct Measurements ◽  
Nearby Stars ◽  
The Masses ◽  
Stellar Masses ◽  
M Dwarf ◽  
Magnitude Difference ◽  
Astrometric Binaries ◽  
Better Than

What is known about the masses of main-sequence stars from the analysis of binary orbits? Double-lined eclipsing binaries are the main source of very precise stellar masses and radii (e.g. Andersen 1997), contributing more than 100 determinations with better than 2% precision over the range 0.6 to 20 Mʘ. For lower-mass stars we are forced to turn to nearby systems with astrometric orbits (e.g. Henry et al. 1993). Not only is the number of good mass determinations from such systems smaller, but also the precision is generally poorer. We are approaching an era when interferometers should have a major impact by supplying good astrometric orbits for dozens of double-lined systems. Already we are beginning to see the sorts of results to expect from this (e.g. Torres et al. 1997). Figure 1. Mass vs. absolute V magnitude for eclipsing binaries (circles) and nearby astrometric binaries (squares) Figure 1 is an updated version of a diagram presented by Henry et al. (1993, their Figure 2). It shows the general run of mass determinations from about 10 Mʘ down to the substellar limit near 0.075 Mʘ. Ninety of the points in Figure 1 are for eclipsing binary masses from Andersen’s review (1991) and are plotted as open circles. The results for eclipsing binaries published since 1991 are plotted as 30 filled circles, adopting the same limit of 2% for the mass precision. In most cases the uncertainties are similar to the size of the symbols. Especially noteworthy is the pair of new points for CM Draconis (Metcalfe et al. 1996) with masses near 0.25 Mʘ. Together with the points for YY Geminorum near 0.6 Mʘ, these are the only M dwarfs that have precise mass determinations. For the most part we are forced to rely on nearby stars with astrometric orbits, to fill in the M dwarf region of the diagram. We have used filled squares in Figure 1 for 29 such systems from Henry et al. (1993), updated using 14 new parallaxes from Hipparcos and 4 from the new Yale Parallax Catalog (1995). Gliese 508 is not included, because it is now known to be a triple, while Gliese 67AB, 570BC, and 623AB are not included because there are not yet any direct measurements of the V magnitude difference for these systems.

scholarly journals SPAN512: A new mid-latitude pulsar survey with the Nançay Radio Telescope

2012 ◽  
Vol 8 (S291) ◽  
pp. 375-377 ◽  
Author(s):  
Gregory Desvignes ◽  
Ismaël Cognard ◽  
David Champion ◽  
Patrick Lazarus ◽  
Patrice Lespagnol ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Large Scale ◽  
High Time ◽  
Frequency Resolution ◽  
Integration Time ◽  
Sensitivity Limit ◽  
Long Period ◽  
Large Bandwidth ◽  
L Band ◽  
Better Than

AbstractWe present an ongoing survey with the Nançay Radio Telescope at L-band. The targeted area is 74° ≲ l < 150° and 3.5° < |b| < 5°. This survey is characterized by a long integration time (18 min), large bandwidth (512 MHz) and high time and frequency resolution (64 μs and 0.5 MHz) giving a nominal sensitivity limit of 0.055 mJy for long period pulsars. This is about 2 times better than the mid-latitude HTRU survey, and is designed to be complementary with current large scale surveys. This survey will be more sensitive to transients (RRATs, intermittent pulsars), distant and faint millisecond pulsars as well as scintillating sources (or any other kind of radio faint sources) than all previous short-integration surveys.

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