arXiv subjects

Jon Holtzman

Publications and source records attributed to Jon Holtzman.

At least 55 records · Page 3Linked to original sources

arXiv2014

Discovery of Two Rare Rigidly-Rotating Magnetosphere Stars in the APOGEE Survey

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) - one of the Sloan Digital Sky Survey III programs -- is using near-infrared spectra of $\sim 100,000$ red giant branch star candidates to study the structure of the Milky Way. In the course of the survey, APOGEE also acquires spectra of hot field stars to serve as telluric calibrators for the primary science targets. We report the serendipitous discovery of two rare, fast-rotating B stars of the $σ$ Ori E type among those blue field stars observed during the first year of APOGEE operations. Both of the discovered stars display the spectroscopic signatures of the rigidly rotating magnetospheres (RRM) common to this class of highly-magnetized ($B \sim 10$ kiloGauss) stars, increasing the number of known RRM stars by $\sim 10 \%$. One (HD 345439) is a main-sequence B star with unusually strong He absorption (similar to $σ$ Ori E), while the other (HD 23478) fits a "He-normal" B3IV classification. We combine the APOGEE discovery spectra with other optical and near-infrared spectra of these two stars, and of $σ$ Ori E itself, to show how near-infrared spectroscopy can be a uniquely powerful tool for discovering more of these rare objects, which may show little/no RRM signatures in their optical spectra. We discuss the potential for further discovery of $σ$ Ori E type stars, as well as the implications of our discoveries for the population of these objects and insights into their origin and evolution.

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arXiv2014

Development of Fiber Fabry-Perot Interferometers as Stable Near-infrared Calibration Sources for High Resolution Spectrographs

We discuss the ongoing development of single-mode fiber Fabry-Perot (FFP) Interferometers as precise astro-photonic calibration sources for high precision radial velocity (RV) spectrographs. FFPs are simple, inexpensive, monolithic units that can yield a stable and repeatable output spectrum. An FFP is a unique alternative to a traditional etalon, as the interferometric cavity is made of single-mode fiber rather than an air-gap spacer. This design allows for excellent collimation, high spectral finesse, rigid mechanical stability, insensitivity to vibrations, and no need for vacuum operation. The device we have tested is a commercially available product from Micron Optics. Our development path is targeted towards a calibration source for the Habitable-Zone Planet Finder (HPF), a near-infrared spectrograph designed to detect terrestrial-mass planets around low-mass stars, but this reference could also be used in many existing and planned fiber-fed spectrographs as we illustrate using the Apache Point Observatory Galactic Evolution Experiment (APOGEE) instrument. With precise temperature control of the fiber etalon, we achieve a thermal stability of 100 $μ$K and associated velocity uncertainty of 22 cm s$^{-1}$. We achieve a precision of $\approx$2 m s$^{-1}$ in a single APOGEE fiber over 12 hours using this new photonic reference after removal of systematic correlations. This high precision (close to the expected photon-limited floor) is a testament to both the excellent intrinsic wavelength stability of the fiber interferometer and the stability of the APOGEE instrument design. Overall instrument velocity precision is 80 cm s$^{-1}$ over 12 hours when averaged over all 300 APOGEE fibers and after removal of known trends and pressure correlations, implying the fiber etalon is intrinsically stable to significantly higher precision.

astro-ph.IM↗

arXiv2014

CSI 2264: Simultaneous optical and infrared light curves of young disk-bearing stars in NGC 2264 with CoRoT and Spitzer-- evidence for multiple origins of variability

We present the Coordinated Synoptic Investigation of NGC 2264, a continuous 30-day multi-wavelength photometric monitoring campaign on more than 1000 young cluster members using 16 telescopes. The unprecedented combination of multi-wavelength, high-precision, high-cadence, and long-duration data opens a new window into the time domain behavior of young stellar objects. Here we provide an overview of the observations, focusing on results from Spitzer and CoRoT. The highlight of this work is detailed analysis of 162 classical T Tauri stars for which we can probe optical and mid-infrared flux variations to 1% amplitudes and sub-hour timescales. We present a morphological variability census and then use metrics of periodicity, stochasticity, and symmetry to statistically separate the light curves into seven distinct classes, which we suggest represent different physical processes and geometric effects. We provide distributions of the characteristic timescales and amplitudes, and assess the fractional representation within each class. The largest category (>20%) are optical "dippers" having discrete fading events lasting ~1-5 days. The degree of correlation between the optical and infrared light curves is positive but weak; notably, the independently assigned optical and infrared morphology classes tend to be different for the same object. Assessment of flux variation behavior with respect to (circum)stellar properties reveals correlations of variability parameters with H$α$ emission and with effective temperature. Overall, our results point to multiple origins of young star variability, including circumstellar obscuration events, hot spots on the star and/or disk, accretion bursts, and rapid structural changes in the inner disk.

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arXiv2013

Measuring Metallicities with HST/WFC3 photometry

We quantified and calibrated the metallicity and temperature sensitivities of colors derived from nine Wide Field Camera 3 (WFC3) filters aboard the Hubble Space Telescope using Dartmouth isochrones and Kurucz atmospheres models. The theoretical isochrone colors were tested and calibrated against observations of five well studied galactic clusters: M92, NGC 6752, NGC 104, NGC 5927, and NGC 6791, all of which have spectroscopically determined metallicities spanning -2.30 < [Fe/H] < +0.4. We found empirical corrections to the Dartmouth isochrone grid for each of the following color magnitude diagrams (CMD) (F555W--F814W, F814W), (F336W-F555W, F814W), (F390M-F555W, F814W) and (F390W-F555W, F814W). Using the empirical corrections we tested the accuracy and spread of the photometric metallicities assigned from CMDs and color-color diagrams (which are necessary to break the age-metallicity degeneracy). Testing three color-color diagrams [(F336W-F555W),(F390M-F555W),(F390W-F555W), vs (F555W-F814W)], we found the colors (F390M-F555W) and (F390W-F555W), to be the best suited to measure photometric metallicities. The color (F390W-F555W) requires much less integration time, but generally produces wider metallicity distributions, and, at very-low metallicity, the MDF from (F390W-F555W) is ~60% wider than that from (F390M-F555W). Using the calibrated isochrones we recovered the overall cluster metallicity to within ~0.1 dex in [Fe/H] when using CMDs (i.e. when the distance, reddening and ages are approximately known). The measured metallicity distribution function (MDF) from color-color diagrams show this method measures metallicities of stellar clusters of unknown age and metallicity with an accuracy of ~0.2 - 0.5 dex using F336W--F555W, ~0.15 - 0.25 dex using F390M-F555W, and ~0.2 - 0.4 dex with F390W-F555W, with the larger uncertainty pertaining to the lowest metallicity range.

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arXiv2013

Discovery of a Dynamical Cold Point in the Heart of the Sagittarius dSph Galaxy with Observations from the APOGEE Project

The dynamics of the core of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy are explored using high-resolution (R~22,500), H-band, near-infrared spectra of over 1,000 giant stars in the central 3 deg^2 of the system, of which 328 are identified as Sgr members. These data, among some of the earliest observations from the SDSS-III/Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the largest published sample of high resolution Sgr dSph spectra to date, reveal a distinct gradient in the velocity dispersion of Sgr from 11-14 km/s for radii >0.8 degrees from center to a dynamical cold point of 8 km/s in the Sgr center --- a trend differing from that found in previous kinematical analyses of Sgr over larger scales that suggest a more or less flat dispersion profile at these radii. Well-fitting mass models with either cored and cusped dark matter distributions can be found to match the kinematical results, although the cored profile succeeds with significantly more isotropic stellar orbits than required for a cusped profile. It is unlikely that the cold point reflects an unusual mass distribution. The dispersion gradient may arise from variations in the mixture of populations with distinct kinematics within the dSph; this explanation is suggested (e.g., by detection of a metallicity gradient across similar radii), but not confirmed, by the present data. Despite these remaining uncertainties about their interpretation, these early test data (including some from instrument commissioning) demonstrate APOGEE's usefulness for precision dynamical studies, even for fields observed at extreme airmasses.

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arXiv2013

The Open Cluster Chemical Analysis and Mapping Survey: Local Galactic Metallicity Gradient with APOGEE using SDSS DR10

The Open Cluster Chemical Analysis and Mapping (OCCAM) Survey aims to produce a comprehensive, uniform, infrared-based dataset for hundreds of open clusters, and constrain key Galactic dynamical and chemical parameters from this sample. This first contribution from the OCCAM survey presents analysis of 141 members stars in 28 open clusters with high-resolution metallicities derived from a large uniform sample collected as part of the SDSS-III/Apache Point Observatory Galactic Evolution Experiment (APOGEE). This sample includes the first high-resolution metallicity measurements for 22 open clusters. With this largest ever uniformly observed sample of open cluster stars we investigate the Galactic disk gradients of both [M/H] and [alpha/M]. We find basically no gradient across this range in [alpha/M], but [M/H] does show a gradient for R_{GC} < 10 kpc and a significant flattening beyond R_{GC} = 10 kpc. In particular, whereas fitting a single linear trend yields an [M/H] gradient of -0.09 +/- 0.03$ dex/kpc --- similar to previously measure gradients inside 13 kpc --- by independently fitting inside and outside 10 kpc separately we find a significantly steeper gradient near the Sun (7.9 <= R_{GC} <= 10) than previously found (-0.20 +/- 0.08 dex/kpc) and a nearly flat trend beyond 10 kpc (-0.02 +/- 0.09 dex/kpc).

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arXiv2013

Very Low Mass Stellar and Substellar Companions to Solar-Like Stars From MARVELS V: A Low Eccentricity Brown Dwarf from the Driest Part of the Desert, MARVELS-6b

We describe the discovery of a likely brown dwarf (BD) companion with a minimum mass of 31.7 +/- 2.0 M_Jup to GSC 03546-01452 from the MARVELS radial velocity survey, which we designate as MARVELS-6b. For reasonable priors, our analysis gives a probability of 72% that MARVELS-6b has a mass below the hydrogen-burning limit of 0.072 M_Sun, and thus it is a high-confidence BD companion. It has a moderately long orbital period of 47.8929 +0.0063/-0.0062 days with a low eccentricty of 0.1442 +0.0078/-0.0073, and a semi-amplitude of 1644 +12/-13 m/s. Moderate resolution spectroscopy of the host star has determined the following parameters: T_eff = 5598 +/- 63, log g = 4.44 +/- 0.17, and [Fe/H] = +0.40 +/- 0.09. Based upon these measurements, GSC 03546-01452 has a probable mass and radius of M_star = 1.11 +/- 0.11 M_Sun and R_star = 1.06 +/- 0.23 R_Sun with an age consistent with less than ~6 Gyr at a distance of 219 +/- 21 pc from the Sun. Although MARVELS-6b is not observed to transit, we cannot definitively rule out a transiting configuration based on our observations. There is a visual companion detected with Lucky Imaging at 7.7 arcsec from the host star, but our analysis shows that it is not bound to this system. The minimum mass of MARVELS-6b exists at the minimum of the mass functions for both stars and planets, making this a rare object even compared to other BDs.

astro-ph.EP↗

arXiv2013

Comparing the Ancient Star Formation Histories of the Magellanic Clouds

We present preliminary results from a new HST archival program aimed at tightly constraining the ancient (>4 Gyr ago) star formation histories (SFHs) of the field populations of the SMC and LMC. We demonstrate the quality of the archival data by constructing HST/WFPC2-based color-magnitude diagrams (CMDs; M_{F555W} ~ +8) for 7 spatially diverse fields in the SMC and 8 fields in the LMC. The HST-based CMDs are >2 magnitudes deeper than any from ground based observations, and are particularly superior in high surface brightness regions, e.g., the LMC bar, which contain a significant fraction of star formation and are crowding limited from ground based observations. To minimize systematic uncertainties, we derive the SFH of each field using an identical maximum likelihood CMD fitting technique. We then compute an approximate mass weighted average SFH for each galaxy. We find that both galaxies lack a dominant burst of early star formation, which suggests either a suppression or an under-fueling of early star formation. From 10-12 Gyr ago, the LMC experienced a period of enhanced stellar mass growth relative to the SMC. Similar to some previous studies, we find two notable peaks in the SFH of the SMC at ~4.5 and 9 Gyr ago, which could be due to repeated close passages with the LMC, implying an interaction history that has persisted for at least 9 Gyr. We find little evidence for strong periodic behavior in the lifetime SFHs of both MCs, suggesting that repeated encounters with the Milky Way are unlikely. Beginning ~3.5 Gyr ago, both galaxies show increases in their SFHs, in agreement with previous studies, and thereafter, track each other remarkably well. (abridged)

astro-ph.CO↗

arXiv2013

Very Metal-poor Stars in the Outer Galactic Bulge Found by the Apogee Survey

Despite its importance for understanding the nature of early stellar generations and for constraining Galactic bulge formation models, at present little is known about the metal-poor stellar content of the central Milky Way. This is a consequence of the great distances involved and intervening dust obscuration, which challenge optical studies. However, the Apache Point Observatory Galactic Evolution Experiment (APOGEE), a wide-area, multifiber, high-resolution spectroscopic survey within Sloan Digital Sky Survey III (SDSS-III), is exploring the chemistry of all Galactic stellar populations at infrared wavelengths, with particular emphasis on the disk and the bulge. An automated spectral analysis of data on 2,403 giant stars in twelve fields in the bulge obtained during APOGEE commissioning yielded five stars with low metallicity([Fe/H]$\le-1.7$), including two that are very metal-poor [Fe/H]$\sim-2.1$ by bulge standards. Luminosity-based distance estimates place the five stars within the outer bulge, where other 1,246 of the analyzed stars may reside. A manual reanalysis of the spectra verifies the low metallicities, and finds these stars to be enhanced in the $α$-elements O, Mg, and Si without significant $α$-pattern differences with other local halo or metal-weak thick-disk stars of similar metallicity, or even with other more metal-rich bulge stars. While neither the kinematics nor chemistry of these stars can yet definitively determine which, if any, are truly bulge members, rather than denizens of other populations co-located with the bulge, the newly-identified stars reveal that the chemistry of metal-poor stars in the central Galaxy resembles that of metal-weak thick-disk stars at similar metallicity.

astro-ph.SR↗

arXiv2012

The Very Short Period M Dwarf Binary SDSS J001641-000925

We present follow-up observations and analysis of the recently discovered short period low-mass eclipsing binary, SDSS J001641-000925. With an orbital period of 0.19856 days, this system has one of the shortest known periods for an M dwarf binary system. Medium-resolution spectroscopy and multi-band photometry for the system are presented. Markov chain Monte Carlo modeling of the light curves and radial velocities yields estimated masses for the stars of M1 = 0.54 +/- 0.07 Msun and M2 = 0.34 +/- 0.04 Msun, and radii of R1 = 0.68 +/- 0.03 Rsun and R2 = 0.58 +/- 0.03 Rsun respectively. This solution places both components above the critical Roche overfill limit, providing strong evidence that SDSS J001641-000925 is the first verified M-dwarf contact binary system. Within the follow-up spectroscopy we find signatures of non-solid body rotation velocities, which we interpret as evidence for mass transfer or loss within the system. In addition, our photometry samples the system over 9 years, and we find strong evidence for period decay at the rate of dP/dt ~8 s/yr. Both of these signatures raise the intriguing possibility that the system is in over-contact, and actively losing angular momentum, likely through mass loss. This places SDSS J001641-000925 as not just the first M-dwarf over-contact binary, but one of the few systems of any spectral type known to be actively undergoing coalescence. Further study SDSS J001641-000925 is on-going to verify the nature of the system, which may prove to be a unique astrophysical laboratory.

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arXiv2012

Chemical Abundances in Field Red Giants from High-Resolution H-Band Spectra using the APOGEE Spectral Linelist

High-resolution H-band spectra of five bright field K, M, and MS giants, obtained from the archives of the Kitt Peak National Observatory (KPNO) Fourier Transform Spectrometer (FTS), are analyzed to determine chemical abundances of 16 elements. The abundances were derived via spectrum synthesis using the detailed linelist prepared for the SDSS III Apache Point Galactic Evolution Experiment (APOGEE), which is a high-resolution near-infrared spectroscopic survey to derive detailed chemical abundance distributions and precise radial velocities for 100,000 red giants sampling all Galactic stellar populations. Measured chemical abundances include the cosmochemically important isotopes 12C, 13C, 14N, and 16O, along with Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. A comparison of the abundances derived here with published values for these stars reveals consistent results to ~0.1 dex. The APOGEE spectral region and linelist is, thus, well-suited for probing both Galactic chemical evolution, as well as internal nucleosynthesis and mixing in populations of red giants using high-resolution spectroscopy.

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arXiv2012

The Nature of Starbursts: III. The Spatial Distribution of Star Formation

We map the spatial distribution of recent star formation over a few x 100 Myr timescales in fifteen starburst dwarf galaxies using the location of young blue helium burning stars identified from optically resolved stellar populations in archival Hubble Space Telescope observations. By comparing the star formation histories from both the high surface brightness central regions and the diffuse outer regions, we measure the degree to which the star formation has been centrally concentrated during the galaxies' starbursts, using three different metrics for the spatial concentration. We find that the galaxies span a full range in spatial concentration, from highly centralized to broadly distributed star formation. Since most starbursts have historically been identified by relatively short timescale star formation tracers (e.g., Halpha emission), there could be a strong bias towards classifying only those galaxies with recent, centralized star formation as starbursts, while missing starbursts that are spatially distributed.

astro-ph.CO↗

arXiv2012

Development of a New, Precise Near-infrared Doppler Wavelength Reference: A Fiber Fabry-Perot Interferometer

We present the ongoing development of a commercially available Micron Optics fiber-Fabry Perot Interferometer as a precise, stable, easy to use, and economic spectrograph reference with the goal of achieving <1 m/s long term stability. Fiber Fabry-Perot interferometers (FFP) create interference patterns by combining light traversing different delay paths. The interference creates a rich spectrum of narrow emission lines, ideal for use as a precise Doppler reference. This fully photonic reference could easily be installed in existing NIR spectrographs, turning high resolution fiber-fed spectrographs into precise Doppler velocimeters. First light results on the Sloan Digital Sky Survey III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectrograph and several tests of major support instruments are also presented. These instruments include a SuperK Photonics fiber supercontinuum laser source and precise temperature controller. A high resolution spectrum obtained using the NIST 2-m Fourier transform spectrometer (FTS) is also presented. We find our current temperature control precision of the FFP to be 0.15 mK, corresponding to a theoretical velocity stability of 35 cm/s due to temperature variations of the interferometer cavity.

astro-ph.IM↗

arXiv2012

The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data

We measure the Milky Way's rotation curve over the Galactocentric range 4 kpc <~ R <~ 14 kpc from the first year of data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). We model the line-of-sight velocities of 3,365 stars in fourteen fields with b = 0 deg between 30 deg < l < 210 deg out to distances of 10 kpc using an axisymmetric kinematical model that includes a correction for the asymmetric drift of the warm tracer population (σ_R ~ 35 km/s). We determine the local value of the circular velocity to be V_c(R_0) = 218 +/- 6 km/s and find that the rotation curve is approximately flat with a local derivative between -3.0 km/s/kpc and 0.4 km/s/kpc. We also measure the Sun's position and velocity in the Galactocentric rest frame, finding the distance to the Galactic center to be 8 kpc < R_0 < 9 kpc, radial velocity V_{R,sun} = -10 +/- 1 km/s, and rotational velocity V_{ϕ,sun} = 242^{+10}_{-3} km/s, in good agreement with local measurements of the Sun's radial velocity and with the observed proper motion of Sgr A*. We investigate various systematic uncertainties and find that these are limited to offsets at the percent level, ~2 km/s in V_c. Marginalizing over all the systematics that we consider, we find that V_c(R_0) < 235 km/s at >99% confidence. We find an offset between the Sun's rotational velocity and the local circular velocity of 26 +/- 3 km/s, which is larger than the locally-measured solar motion of 12 km/s. This larger offset reconciles our value for V_c with recent claims that V_c >~ 240 km/s. Combining our results with other data, we find that the Milky Way's dark-halo mass within the virial radius is ~8x10^{11} M_sun.

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arXiv2012

The Apache Point Observatory Galactic Evolution Experiment: First Detection of High Velocity Milky Way Bar Stars

Commissioning observations with the Apache Point Observatory Galactic Evolution Experiment (APOGEE), part of the Sloan Digital Sky Survey III, have produced radial velocities (RVs) for ~4700 K/M-giant stars in the Milky Way bulge. These high-resolution (R \sim 22,500), high-S/N (>100 per resolution element), near-infrared (1.51-1.70 um; NIR) spectra provide accurate RVs (epsilon_v~0.2 km/s) for the sample of stars in 18 Galactic bulge fields spanning -1 -32 deg. This represents the largest NIR high-resolution spectroscopic sample of giant stars ever assembled in this region of the Galaxy. A cold (sigma_v~30 km/s), high-velocity peak (V_GSR \sim +200 km/s) is found to comprise a significant fraction (~10%) of stars in many of these fields. These high RVs have not been detected in previous MW surveys and are not expected for a simple, circularly rotating disk. Preliminary distance estimates rule out an origin from the background Sagittarius tidal stream or a new stream in the MW disk. Comparison to various Galactic models suggests that these high RVs are best explained by stars in orbits of the Galactic bar potential, although some observational features remain unexplained.

astro-ph.GA↗

arXiv2012

Observational Constraints on the Molecular Gas Content in Nearby Starburst Dwarf Galaxies

Using star formation histories derived from optically resolved stellar populations in nineteen nearby starburst dwarf galaxies observed with the Hubble Space Telescope, we measure the stellar mass surface densities of stars newly formed in the bursts. By assuming a star formation efficiency (SFE), we then calculate the inferred gas surface densities present at the onset of the starbursts. Assuming a SFE of 1%, as is often assumed in normal star-forming galaxies, and assuming that the gas was purely atomic, translates to very high HI surface densities (~10^2-10^3 Msun pc^-2), which are much higher than have been observed in dwarf galaxies. This implies either higher values of SFE in these dwarf starburst galaxies or the presence of significant amounts of H_2 in dwarfs (or both). Raising the assumed SFEs to 10% or greater (in line with observations of more massive starbursts associated with merging galaxies), still results in HI surface densities higher than observed in 10 galaxies. Thus, these observations appear to require that a significant fraction of the gas in these dwarf starbursts galaxies was in the molecular form at the onset of the bursts. Our results imply molecular gas column densities in the range 10^19-10^21 cm^-2 for the sample. In those galaxies where CO observations have been made, these densities correspond to values of the CO-H_2 conversion factor (X_CO) in the range >3-80x10^20 cm^-2 (K km s^-1)^-1, or up to 40x greater than Galactic X_CO values.

astro-ph.CO↗

arXiv2012

Quenched Cold Accretion of a Large Scale Metal-Poor Filament due to Virial Shocking in the Halo of a Massive z=0.7 Galaxy

Using HST/COS/STIS and HIRES/Keck high-resolution spectra, we have studied a remarkable HI absorbing complex at z=0.672 toward the quasar Q1317+277. The HI absorption has a velocity spread of 1600 km/s, comprises 21 Voigt profile components, and resides at an impact parameter of D=58 kpc from a bright, high mass [log(M_vir/M_sun) ~ 13.7] elliptical galaxy that is deduced to have a 6 Gyr old, solar metallicity stellar population. Ionization models suggest the majority of the structure is cold gas surrounding a shock heated cloud that is kinematically adjacent to a multi-phase group of clouds with detected CIII, CIV and OVI absorption, suggestive of a conductive interface near the shock. The deduced metallicities are consistent with the moderate in situ enrichment relative to the levels observed in the z ~ 3 Ly-alpha forest. We interpret the HI complex as a metal-poor filamentary structure being shock heated as it accretes into the halo of the galaxy. The data support the scenario of an early formation period (z > 4) in which the galaxy was presumably fed by cold-mode gas accretion that was later quenched via virial shocking by the hot halo such that, by intermediate redshift, the cold filamentary accreting gas is continuing to be disrupted by shock heating. Thus, continued filamentary accretion is being mixed into the hot halo, indicating that the star formation of the galaxy will likely remain quenched. To date, the galaxy and the HI absorption complex provide some of the most compelling observational data supporting the theoretical picture in which accretion is virial shocked in the hot coronal halos of high mass galaxies.

astro-ph.CO↗

arXiv2012

Very Low-Mass Stellar and Substellar Companions to Solar-Like Stars from MARVELS I: A Low Mass Ratio Stellar Companion to TYC 4110-01037-1 in a 79-day Orbit

TYC 4110-01037-1 has a low-mass stellar companion, whose small mass ratio and short orbital period are atypical amongst solar-like (Teff ~< 6000 K) binary systems. Our analysis of TYC 4110-01037-1 reveals it to be a moderately aged (~<5 Gyr) solar-like star having a mass of 1.07 +/- 0.08 MSun and radius of 0.99 +/- 0.18 RSun. We analyze 32 radial velocity measurements from the SDSS-III MARVELS survey as well as 6 supporting radial velocity measurements from the SARG spectrograph on the 3.6m TNG telescope obtained over a period of ~2 years. The best Keplerian orbital fit parameters were found to have a period of 78.994 +/- 0.012 days, an eccentricity of 0.1095 +/- 0.0023, and a semi-amplitude of 4199 +/- 11 m/s. We determine the minimum companion mass (if sin i = 1) to be 97.7 +/- 5.8 MJup. The system's companion to host star mass ratio, >0.087 +/- 0.003, places it at the lowest end of observed values for short period stellar companions to solar-like (Teff ~< 6000 K) stars. One possible way to create such a system would be if a triple-component stellar multiple broke up into a short period, low q binary during the cluster dispersal phase of its lifetime. A candidate tertiary body has been identified in the system via single-epoch, high contrast imagery. If this object is confirmed to be co-moving, we estimate it would be a dM4 star. We present these results in the context of our larger-scale effort to constrain the statistics of low mass stellar and brown dwarf companions to FGK-type stars via the MARVELS survey.

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