2017AB proposals

We propose to address two outstanding questions concerning exoplanets, both requiring large new datasets: (1) What is the exoplanet mass/period distribution, in particular for the poorly-represented ``Hot Neptune`` and ``Warm Jupiter`` populations, and (2) Why are the orbital axes of some planets so strongly inclined to the rotational axes of their parent stars? To do this, we will combine intensive observations with
the new LCO- NRES spectrograph network with discovery data from the Transiting Exoplanet Survey Satellite (TESS -- to be launched near the end of calendar 2017), and from existing space- and ground-based transiting planet discovery facilities.

Our proposed project will carry out all of LCO's observing commitments to the TESS mission, but will greatly extend the TESS sample in order to answer the above science questions, which are uniquely accessible to LCO-NRES. The project will run for 6 semesters, obtain repeated spectra of some 500 exoplanet host stars
and use a total of 12,700 observing hours, about half of which will come from the LCO Key Project pool. Our main activities will be to bring NRES up to its full potential as a global observing system, to develop software tools to enhance its scientific productivity, to carry out and analyze the needed observations for our science program, and to publish our scientific and technical results promptly.

In 2017, the new near-IR Habitable-zone Planet Finder (HPF) spectrograph will begin surveying nearby mid-late M dwarfs for low-mass exoplanets. We propose to use the LCO network to acquire V- and i-band photometry of our HPF survey targets every night they are observable. These observations will facilitate the identification of rotation periods, magnetic cycles, and other activity phenomena, providing valuable insight into the magnetic fields of fully convective stars, and be crucial in the separation of Doppler exoplanet signals from activity-induced noise. Our targets are bright enough to be observed with any of the LCO telescopes, and distributed across the northern sky. Thus, our program takes maximal advantage of LCO`s flexibility, especially as the new northern and equatorial telescopes come online.

LCO is becoming a one-stop shop for exoplanet observations. With the deployment of NRES it will be capable of obtaining both RVs to measure the orbit and photometry to measure the transit, all using a robotic telescope network. This is especially useful for observations of transiting planet candidates, confirming their planetary nature and measuring their orbit and mass, along with studying the systems architecture. Such observations are currently a bottleneck due to the lack of sufficient observing resources. We will use LCO to observe transiting planets identified by the Kepler, K2, KELT, HAT- South, and TESS surveys. We have identified 4 observing activities where LCO will make a significant contribution: In Part I we will detect transiting warm Jupiters, to study the inflated gas giant planet conundrum. In Part II we will observe transiting systems showing transit timing variations, to look for small planets in wide orbits, beyond the reach of the RV method. In Part III we will observe planet candidates orbiting bright and quiet stars which once confirmed will become prime targets for detailed characterization. In Part IV we will observe transit candidates to check whether the transit signal seen in the survey data is in fact a false positive originating from a deep eclipse on a nearby star diluted with the target in the wide PSF of the survey instrument. Each part is independent of the rest while combined they will make LCO a leading player in the exoplanets field.

Current planet formation theories predict that planets with semi-major axes between 1-10 AU should be abundant, yet they lie beyond the detection limits of most planet finding techniques. To this day, this important region of planetary parameter space remains largely unexplored. Discovering them is critical in understanding the physical processes that drive planet formation. - We propose a 3-year gravitational microlensing Key Project to discover new exoplanets in the cold outer regions of planetary systems, including free-floating planets and, potentially, planets around stellar remnants. Previous microlensing programs were limited in their ability to characterize source stars and could not obtain uninterrupted 24/7 observational coverage. We propose a novel approach that combines a multi-wavelength survey with reactive follow-up observations, and which relies on the unique capabilities of the global Las Cumbres Observatory (LCO) network and its newly deployed wider-field cameras. - We will achieve enhanced sensitivity to planets with smaller masses (less than 10 MEarth) by placing better constraints on the spectral type of the source stars and by employing software that optimizes light curve coverage during the most planet-sensitive sections of the microlensing event. We will thus be able to better constrain the physical properties of these new planets exclusively based on LCO data.

Comet activity varies as different parts of the nucleus are illuminated by sun light, tracing het- erogeneities. Comet 41P will pass Earth very closely this Spring, and is therefore a target of high scientific interest. LCO provides the unique opportunity to acquire high-quality, high-cadence pho- tometry of comets, obtained at uniform-cadence with the same instrument. We request 144 h of observing time on the LCOs 1-m telescopes to reveal rotational, seasonal, and evolutionary changes in the comet’s activity. We will acquire 2-day sampling of its dust (r’) and gas (g’), and will trigger a follow-up program when we detect evidence of outbursts. This dataset will allow us to develop, test, and refine algorithms for the automated detection of outbursts in LSST data, which will be crucial to interpret comet light curves amid the vast amount of data that the survey will produce. 41P’s apparition provides a proxy for a broad range of observing conditions. We will use this program to prototype an early warning system to detect small outbursts, and to activate rapid follow-up observations.

Transiting planets around bright stars are key objects for exploring the physical properties of planets outside the Solar System. The US-based HATNet and HATSouth surveys are leading efforts for discovering and characterizing these planets. Candidate planets that are identified by the surveys must be confirmed through high-precision photometric and spectroscopic follow-up observations. Here we propose to use the Sinistro imagers and NRES spectrographs on the LCOGT 1m network to carry out these observations for dozens of candidates, which will contribute to the discovery and characterization of ∼ 15 new well characterized planets. This effort will focus on confirming Neptune-size planets, long period planets, and planets around M dwarfs, with the goal of expanding the sample of such objects known around bright stars. The planets discovered through this effort will be amenable to detailed follow-up studies, such as transmission spectroscopy with JWST.

We will use the rapid-response mode of the LCO network to followup high-magnification microlens- ing events being observed by the Spitzer microlens parallax program. These events have the highest intrinsic sensitivity to planets, but must be followed intensively over the peak of the event in order to capture that sensitivity. We will use LCO observations to find and characterize 4 ± 2 planetary perturbations in these events to measure the mass ratio and scaled projected separation of the planet and also measure finite source effects. By combining these data with the Spitzer parallax data, we will measure the masses of the planets and the distance between the Sun and the planetary system. Through a complete statistical analysis of the Spitzer microlensing parallax sample includ- ing these events observed by LCO, we will make the first measurement of the galactic distribution of planets.

We propose nightly photometric monitoring of 2 exoplanet host stars with the LCO 1-m network (a continuation of program LCO2016B-009). The proposed program is essential to the success of an accepted Gemini survey, which is the first aimed at the characterization of exoplanet clouds. Since understanding clouds is necessary for measuring exoplanet compositions, this an important step forward in the field of exoplanet science. The Gemini survey will measure scattering signatures in blue optical transmission spectra during multiple observations to determine cloud species. However, while the blue optical is the only spectral region where clouds can be directly detected, it is also the spectral region where stellar activity produces strong signals in transmission. The proposed LCO program is required in order to dis-entangle contaminating stellar signals from true planetary signals. The stellar contribution varies significantly depending on the number of starspots visible, and only independent measurements of the stellar spot level will enable distinction between the two signals. Long-term, frequent, photometric monitoring throughout the Gemini survey is the only way to measure the stellar spot level at the time of each transit event, by allowing us to model the stellar periodicity, spot evolution and estimate the non-spotted stellar brightness. This is the only way to correct the transmission spectra for stellar effects and accurately characterize the planetary cloud species.

We propose to use the Doppler technique on time-resolved LCO/NRES spectroscopy to infer the minimum mass of a likely compact object companion to a recently discovered ultra metal-poor star. Data already acquired suggests that the object may be a neutron star or stellar-mass black hole, but the sparse radial velocity sampling currently available does not exclude the possibility that the companion is a massive white dwarf. If the compact object is confirmed to be a neutron star or black hole, it would be among the closest known massive compact objects to the Sun. The visible ultra metal-poor star is nearby and bright enough that Gaia will eventually measure the inclination of the system’s orbit. It will therefore be possible to measure the mass of the compact object. The low metallicity of the visible star suggests that it and the compact object likely formed in the distant past, making the unseen companion the oldest compact object in the solar neighborhood.

The magnetic activity of the Sun becomes stronger and weaker over roughly an 11-year cycle. Decades of observations from Mount Wilson and Lowell revealed that other stars also show regular activity cycles, and identified two possible relationships between the length of the cycle and the rotation rate of the star. Neither of these relationships match the properties of the Sun, a peculiarity that demands further investigation. Recent work suggests that the Sun’s rotation rate and magnetic field may be in a transitional phase that occurs in all middle-aged stars, but additional observations are needed to test this hypothesis. We propose to begin long-term monitoring of Ca ii H and K emission for a sample of bright stars with known rotation rates, to identify the short activity cycles that are predecessors of the 11-year solar cycle. For most of these targets, asteroseismic masses and ages are soon expected from the Transiting Exoplanet Survey Satellite (TESS). We initially focus on 24 stars that are accessible from the south, but we will seek long-term status in 2018A for the full sample.

Gamma-ray bursts are produced by the explosion of 20-100 solar mass stars. They have been detected up to redshift z ∼ 8 − 9 and their optical/NIR emission is bright enough to provide high signal to noise ratio spectra. Unfortunately, the rarity of such high-z events requires every possible effort to promptly observe as many GRB as possible. In this proposal we request to utilize the LCO network of 1m and 2m telescopes in order to expand our sky coverage and identify possible high-z candidates to be subsequently observed with our 4-8m NIR dedicated facilities. We expect to increase by 25% our sample of z ∼ 6 GRBs and to provide for the first time a high-resolution spectrum of a z >∼ 7 GRB: this data will shed light on the chemical enrichment of the Universe at such early stage as well as provide constrain on reionization. Furthermore, identifying such objects will provide invaluable resources for future NIR observation with the James Webb Space Telescope and Thirty meter facilities.

We request time to use NRES in shared-risk mode at the 1-m LCO telescope in CTIO. Our pro- gram aims to monitor temporal changes in spectral lines that are chromospherically or sunspot sensitive. Our goal is to characterize the degree to which this technique can provide a measure of stellar rotation periods for older less-active Sun-like stars where photometric means fail. The result promises to open a new field of ground-based observations of older Sun-like stars whose ages provide an important window on the time evolution of planetary systems.

We propose to observe the optical counterparts of two black hole binary systems. The scientific goals are 1) to refine the system inclination and mass of the black hole; 2) to understand the accretion flow in the quiescent state; 3) to establish templates for the identification of black hole systems in quiescence in future time domain surveys. Point 3 is of particular importance in the LIGO era. The demographics of black hole binaries are currently subject to an intense selection effect because they are identified initially through their X-ray outbursts. Identification by optical properties would be a significant improvement in this regard.

The ability to monitor galactic novae at high cadence is revealing new puzzles about just how white dwarf stars explode and lose mass. High cadence absorption line spectroscopy shows that the mass loss in many novae is highly complex. We can resolve the origin of absorption systems; correlations with OIR photometry are revealing insights into the process. We request a total of 2 nights with LCO/NRES to a.) obtain a cross-calibration with our high dispersion Chiron spectra, and b.) obtain a high-cadence sequence of synoptic spectra of the next bright galactic nova.

Many open questions in supernova (SN) physics rely on the connection between core-collapse SNe and their massive progenitor stars. It is now possible to directly investigate SN progenitor systems, but only for the small fraction of nearby SNe with pre-explosion Hubble Space Telescope (HST) imaging. Therefore, each new discovery must be optimally exploited in order to obtain as much information as possible connecting SN and progenitor star. We propose to use the unique rapid response and monitoring capabilities of the LCO Global Telescope Network to investigate the early-time light curves and spectroscopic evolution of core-collapse SNe that have pre-explosion HST imaging. The early-time light curve is sensitive of the radius of the progenitor star, and we will use this information to produce an independent constraint on progenitor star systems.

Periodic variability in quasars has been predicted as an observational signature of supermassive black hole binaries (SMBHBs), which should be a common product of the hierarchy growth of galaxies. We have performed a systematic search in the Pan-STARRS1 Medium Deep Survey and identified a number of periodic quasar candidates with variations over > 1.5 cycles. We have been monitoring them with the Large Monolithic Imager at the Discovery Channel Telescope, since a long baseline is essential in order to break a false positive signal due to normal, stochastic quasar variability. Here we propose to continue and expand our imaging campaign with LCO. The proposed observations will be able to verify strong SMBHB candidates that are in the gravitational wave regime of orbital decay accessible to the Pulsar Timing Arrays and for the upcoming era of the Large Synoptic Survey Telescope.

HD96670 is a single-line spectroscopic binary made up of an O8.5V primary with variable HeII emission, and an unseen secondary (Sota, et al. 2014). We observed the source and determined a mass function of f (M ) = 0.1161 ± 0.0046 M Sun. For an O8.5 primary, this implies a minimum secondary mass of M2 > 3.5±0.5MS un, ruling out a neutron star or white dwarf secondary. We dont see any spectral signatures that can be associated with a main sequence companion > 3.5M Sun. The source also shows X-ray emission above 10keV with a photon index ∼ 2.5 (Grindlay, et al. in prep). These arguments favor a black hole secondary, if confirmed this would be the third to fifth dynamically confirmed black hole high mass X-ray binary known in the galaxy (Besides Cyg X-1 and MWC 656).

For over 15 years there has been clear evidence for an asteroid spin barrier, where asteroids larger than 150 m in diameter (H=22) do not rotate faster than 11 rev/day (P=2.2 hours). However, the asteroid population near the spin barrier has not been well studied because these objects are fainter than what the amateur community can typically observe. Additionally, until recently, there has not been enough meter-class telescope time available to conduct a large scale population study. This proposed work will almost double the number of quality rotational studies of asteroids between H=20 (300 m) and H=23 (100 m). The LCO network provides a unique opportunity to provide physical characterization of medium sized near Earth asteroids soon after discovery. While the discovery rate of these asteroids will greatly increase with LSST, the window available for their characterization will remain unchanged. Therefore, an infrastructure like the one proposed here is required to be able to process LSST alerts in real time and submit time domain observations.

Our program aims to accomplish followup photometry and spectroscopy of newly discovered candi- date cataclysmic variables (CVs) in current optical sky surveys (CRTS, MASTER, ASAS-SN), with particular emphasis on low luminosity, short period dwarf novae that have infrequent outbursts, related period bouncers and systems containing highly magnetic white dwarfs. These objects are crucial for understanding the nature of close binary evolution, particularly at the shortest orbital periods (60-90 min). In addition, the rare but important class of double-degenerate systems, po- tential progenitors of Type Ia SN are also potential candidates from these surveys. The primary goals are to obtain spectra to confirm the CV nature and delineate the object types, and obtain light curves to find the orbital periods, an essential key parameter to determine the evolutionary status. We need to accumulate large numbers to test population model predictions for angular momentum loss and evolution. For this reason, we request long term status to accumulate data for about 100 systems, using 3 hr continuous photometry (in g and r) for 2-3 objects/ month and spectra of about 4/month throughout the 3 yr program. We will use larger telescope access by the PI and CoIs at APO, MDM, Caltech and SAAO to accomplish radial velocities of the most interesting targets determined by LCO. This first year will serve as a testbed for the addition of ZTF candidates at the end of 2017.

NGC3783 is one of the brightest and nearest broad-lined Seyfert galaxies. As such, it is one of only a handful of objects where we can attempt to directly compare black hole mass measurements based on reverberation mapping (which is limited by temporal resolution) and stellar dynamical modeling (which is limited by spatial resolution). To date, such comparisons have only been carried out for two Seyferts. Our team has been working to increase the number of such comparisons, and we have two more nearing completion, with 2-3 additional objects in progress. We have exhausted the sample of northern hemisphere targets, but LCO provides a unique set of capabilities for carrying out spectrophotometric monitoring programs in the southern hemisphere. NGC3783 is our top priority southern target, especially as it is not included in the LCO AGN Key Project. All black hole mass estimates at different look-back times are based on reverberation mapping and/or dynamical modeling results for < 200 nearby objects. Direct comparisons of these techniques are necessary to understand the magnitude of the biases and limitations inherent in each technique and to investigate the possibility of offsets in their resultant mass scales, which may profoundly affect our understanding of black hole growth and evolution.

Sub-luminous X-ray binaries are transiently accreting neutron stars or black holes that show anoma- lously faint X-ray outbursts. It is expected that these objects represent rare, exciting sub-classes of X-ray binaries: i) black holes or neutron stars accreting from a H-poor companion star in a very tight orbit, which are prime targets for future gravitational wave searches and important tests for binary evolution models, or ii) neutron stars with magnetic fields strong enough to propeller the accreted gas away, a very interesting but poorly understood form of accretion. Only a few objects in each of these two sub-classes are currently known and there is high merit to search for more of them. Here we propose NOAO/LCO optical imaging observations of two sub-luminous X-ray binaries for which we obtained optical spectra; one with a strong Hα emission line and one that lacks any H feature. Our main aim is to search for optical modulations that allow us to measure the orbital periods of these two objects and hence distinguish between the above two scenarios.

Most howardite-eucrite-diogenite meteorites (HEDs) are generally thought to be collisionaly ejected debris from asteroid (4) Vesta. However, several of the HED group meteorites (for example Bunburra Rockhole, Ibitra, Pasamonte, PCA 91007, NWA 011, A-881394, and others) show oxygen isotope ratios suggesting that they must have originated in multiple other asteroids. Those aster- oids are parts of disrupted planetesimals - first bodies that formed in the Solar System four billion years ago. Identification of those asteroids, confirmation of their link to the anomalous meteorites, determination of their properties and distribution in Solar System is essential to understanding early phases of planetary formation and evolution.

Results of a recent survey of Trojan asteroid lightcurves with the Kepler mission have identified a population of asteroids with rotational periods less than 100 hours. Preliminary compositional data is available for approximately half of the sample, and all but one target have the same taxonomic type. In this proposal, we address the question: do all slow rotators within the Trojans have the same compositional type with spectra from the Las Cumbres Observatory Faulkes Telescopes.

Using the complete sample of 4846 solar-type stars within 67 pc, we will provide the unbiased statistics of close (P < 1000d) subsystems in hierarchical multiples. Diagnostic features such as period and eccentricity distributions, mass and period ratios will help to establish the relevance of alter- native formation mechanisms of those subsystems and will lead to the understanding (eventually predicting) stellar multiplicity. This work continues the CHIRON survey interrupted in 2016.

Using a chi-squared spectral energy distribution fit of VRI, 2MASS JHK, and WISE data to the BT-Settl model grid, we are characterizing a total of 1874 of the nearest red dwarfs by pro- viding systematically determined luminosities, Teff, and radii. One result of this program is the identification of young/old stars via their correspondingly large/small radii. Radii for these stars can be used as proxies to map stellar ages for stars in the solar neighborhood from which we can piece together our Galaxy’s history. As part of the PI’s PhD thesis, we wish to gather short-term variability data for 15 candidate pre-main sequence stars to serve as indicators of these stars’ youth.

Binarity in Carbon-enhanced metal-poor stars

ANU contribution to AGN key project.

ANU contribution to Transiting Exoplanets key project.

ANU contribution to Global Supernova key project.