Austin Rothermich
A5062529261- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Geological and Geochemical Analysis
- Metallurgical Processes and Thermodynamics
- History and Developments in Astronomy
- Geomagnetism and Paleomagnetism Studies
- Planetary Science and Exploration
- Isotope Analysis in Ecology
- Space Science and Extraterrestrial Life
- Galaxies: Formation, Evolution, Phenomena
- SAS software applications and methods
- Metallurgy and Cultural Artifacts
- High-pressure geophysics and materials
- Food Quality and Safety Studies
- Advanced Chemical Physics Studies
- Laser-induced spectroscopy and plasma
- Geophysics and Gravity Measurements
City University of New York
2022-2025
The Graduate Center, CUNY
2022-2025
American Museum of Natural History
2021-2025
University of Central Florida
2020-2024
Hunter College
2024
We present final Spitzer trigonometric parallaxes for 361 L, T, and Y dwarfs. combine these with prior studies to build a list of 525 known dwarfs within 20 pc the Sun, 38 which are presented here first time. Using published photometry spectroscopy as well our own follow-up, we an array color-magnitude color-color diagrams further characterize census members, provide polynomial fits bulk trends. characterizations, assign each object $T_{\rm eff}$ value judge sample completeness over bins...
Abstract A complete accounting of nearby objects—from the highest-mass white dwarf progenitors down to low-mass brown dwarfs—is now possible, thanks an almost set trigonometric parallax determinations from Gaia, ground-based surveys, and Spitzer follow-up. We create a census objects within Sun-centered sphere 20 pc radius check published literature decompose each binary or higher-order system into its separate components. The result is volume-limited ∼3600 individual star formation products...
Abstract We present results from conducting a theoretical chemical analysis of sample benchmark companion brown dwarfs whose primary star is type F, G, or K. summarize the entire known these types systems, termed “compositional benchmarks,” that are in literature recently published as key systems study order to best understand dwarf chemistry and condensate formation. Via mass balance stoichiometric calculations, we predict median atmospheric oxygen sink <?CDATA ${17.8}_{-2.3}^{+1.7} \% $?>...
Abstract Beyond our Solar System, aurorae have been inferred from radio observations of isolated brown dwarfs 1,2 . Within giant planets auroral emission with signatures across the electromagnetic spectrum including infrared H 3 + and methane. Isolated in searched for corresponding features, but only null detections reported CWISEP J193518.59-154620.3. (W1935 short) is an dwarf a temperature approximately 482 K. Here we report James Webb Space Telescope strong methane W1935 at 3.326 μm....
Abstract We present Spitzer follow-up imaging of 95 candidate extremely cold brown dwarfs discovered by the Backyard Worlds: Planet 9 citizen science project, which uses visually perceived motion in multiepoch Wide-field Infrared Survey Explorer (WISE) images to identify previously unrecognized substellar neighbors Sun. measure [3.6]–[4.5] color phototype our dwarf candidates, with an emphasis on pinpointing coldest and closest Y within sample. The combination WISE astrometry provides...
We present the discovery of CWISE J050626.96$+$073842.4 (CWISE J0506$+$0738), an L/T transition dwarf with extremely red near-infrared colors discovered through Backyard Worlds: Planet 9 citizen science project. Photometry from UKIRT and CatWISE give a $(J-K)_{\rm MKO}$ color 2.97$\pm$0.03 mag $J_{\rm MKO}-$W2 4.93$\pm$0.02 mag, making J0506$+$0738 reddest known free-floating in both colors. confirm nature using Keck/NIRES spectroscopy establish that it is low-gravity late-type dwarf. The...
Abstract We report the identification of 89 new systems containing ultracool dwarf companions to main-sequence stars and white dwarfs, using citizen science project Backyard Worlds: Planet 9 cross-reference between Gaia CatWISE2020. 32 these 33 host were followed up with spectroscopic observations, companion spectral types ranging from M7–T9 G2–M9. These exhibit diverse characteristics, young old ages, blue very red morphologies, potential membership known moving groups, evidence binarity in...
We present the discoveries of WISEA J041451.67-585456.7 and J181006.18-101000.5, two low-temperature (1200$-$1400 K), high proper motion T-type subdwarfs. Both objects were discovered via their ($>$0.5 arcsec yr$^{-1}$); J181006.18-101000.5 as part NEOWISE survey citizen science project Backyard Worlds; Planet 9. have confirmed both brown dwarfs with follow-up near-infrared spectroscopy. Their spectra colors are unique amongst known dwarfs, some consistent L-type other resembling those...
Abstract We conducted a search for new ultracool companions to nearby white dwarfs using multiple methods, including the analysis of colors and examination images in both optical infrared. Through this process, we identified 51 previously unrecognized systems with candidate companions. 31 these are resolved at least one catalog, all but six confirmed as comoving via common proper motion consistent parallax measurements (when available). have followed up four near-infrared spectroscopy...
Abstract The Disk Detective project, a citizen science initiative, aims to identify circumstellar discs around stars by detecting objects with infrared (IR) excess using data from the Wide-field Infrared Survey Explorer (WISE). In this study, we investigate SIPS J2045-6332, potential brown dwarf significant IR in WISE and 2MASS bands, initially identified project volunteers. Despite early indicators of disc, discrepancies between observed brightness expected Spectral Energy Distribution...
Abstract We report the results of a spectroscopic survey candidate T subdwarfs identified by Backyard Worlds: Planet 9 program. Near-infrared spectra 31 sources with red J − W2 colors and large -band reduced proper motions show varying signatures subsolar metallicity, including strong collision-induced H 2 absorption, obscured methane water features, weak K i absorption. These metallicity are supported spectral model fits 3D velocities, indicating thick disk halo population membership for...
Abstract We investigate the effects of surface gravity, effective temperature, and cloudiness on potassium doublet (K i ) at 1.17 μ m in brown dwarf spectra. Using pseudo-Voigt profiles to fit K Sonora Diamondback atmospheric model spectra, we find that gravity affect spectra differently mid late-L dwarfs. The full-width half-maximum (FWHM) is strongly correlated with while maximum depth correlates cloudiness. This method allows us separate clouds doublet. also FWHM can help estimate...
Abstract We present the first brown dwarf spectral binary characterized with JWST: WISE J014656.66+423410.0, coldest blended-light straddling T/Y transition. obtained a moderate resolution ( R ∼ 2700) G395H spectrum of this unresolved JWST/NIRSpec and we fit it to late T Y spectra from JWST/NIRSpec, model comparable temperatures, both as individual pairs mimicking an system. find that tightly separated is likely composed two unequal-brightness sources magnitude difference 0.50 ± 0.08 mag in...
Through the Backyard Worlds: Planet 9 citizen science project we discovered a late-type L dwarf co-moving with young K0 star BD+60 1417 at projected separation of 37" or 1662 AU. The secondary - CWISER J124332.12+600126.2 (W1243) is detected in both CatWISE2020 and 2MASS reject tables. photometric distance CatWISE proper motion match that primary within ~1sigma our estimates for chance alignment yield zero probability. Follow-up near infrared spectroscopy reveals W1243 to be very red...
Abstract We present the discovery of VHS J183135.58−551355.9 (hereafter J1831−5513), an L/T transition dwarf identified as a result its unusually red near-infrared colors ( J − K S = 3.633 ± 0.277 mag; W 2 6.249 0.245 mag) from VISTA Hemisphere Survey and CatWISE2020 surveys. obtain low-resolution spectroscopy J1831−5513 using Magellan Folded port InfraRed Echellette spectrograph to confirm extremely nature assess features sensitive surface gravity (i.e., youth). Its spectrum shows multiple...
Through the Backyard Worlds: Planet 9 citizen science project, we have identified a wide-separation ($\sim$10', $\sim$9900 au projected) substellar companion to nearby ($\sim$17.5 pc), mid-M dwarf Ross 19. We developed new formalism for determining chance alignment probabilities based on BANYAN $\Sigma$ tool, and find 100% probability that this is physically associated pair. detailed examination of 19A, system metal-poor ([Fe/H]=$-$0.40$\pm$0.12) with an age 7.2$^{+3.8}_{-3.6}$ Gyr....
Abstract We present the discovery of 13 new widely separated T dwarf companions to M primaries, identified using Wide-field Infrared Survey Explorer/NEOWISE data by CatWISE and Backyard Worlds: Planet 9 projects (hereafter BYW). This sample represents an ∼60% increase in number known + systems, allows us probe most extreme products binary/planetary system formation, a space made available CatWISE2020 catalog BYW effort. Highlights among are WISEP J075108.79-763449.6, previously T9 thought be...
Abstract We report the discovery of a high-velocity, very low-mass star or brown dwarf whose kinematics suggest it is unbound to Milky Way. CWISE J124909.08+362116.0 was identified by citizen scientists in Backyard Worlds: Planet 9 program as high-proper-motion ( μ = 0.″9 yr −1 ) faint red source. Moderate-resolution spectroscopy with Keck/NIRES reveals be metal-poor early L subdwarf large radial velocity (−103 ± 10 km s ), and its estimated distance 125 8 pc yields speed 456 27 Galactic...
We present the discovery of WISEA J083011.95+283716.0, first Y dwarf candidate identified through Backyard Worlds: Planet 9 citizen science project. this object as a red, fast-moving source with faint $W2$ detection in multi-epoch \textit{AllWISE} and unWISE images. have characterized Spitzer Space Telescope \textit{Hubble Telescope} follow-up imaging. With mid-infrared detections \textit{Spitzer}'s \emph{ch1} \emph{ch2} bands flux upper limits Hubble $F105W$ $F125W$ filters, we find that is...
Abstract We have used data from the UKIRT Hemisphere Survey to search for substellar members of Hyades cluster. Our recovered several known members, and two brown dwarfs that we suggest may be based on a new kinematic analysis. uncovered thirteen candidates, obtained near-infrared follow-up spectroscopy each with IRTF/SpeX. Six candidates spectral types between M7 L0 are ruled out as potential their photometric distances (≳100 pc). The remaining seven L5 T4, all five showing strong...
We present the discovery of CWISE J151044.74$-$524923.5, a wide low-mass companion to nearby ($\sim$24.7 pc) system L 262-74, which was identified through Backyard Worlds: Planet 9 citizen science project. detail properties system, and we assess that this is mid-L dwarf, will need be verified spectroscopically. With an angular separation 74\farcs3, estimate projected physical $\sim$1837 au from central system.
We present the discovery of CWISE J203546.35-493611.0, a peculiar M8 companion to M4.5 star APMPM J2036-4936 discovered through citizen science project Backyard Worlds: Planet 9. Given J203546.35-493611.0's proper motion ($\mu_{\alpha}$, $\mu_{\delta}$) = ($-$126$\pm$22, $-$478$\pm$23) and angular separation 34.2$''$ from 2036-4936, we calculate chance alignment probability $1.15 \times 10^{-6}$. Both stars in this system appear be underluminous, spectrum obtained for J203546.35-493611.0...
We present results from conducting a theoretical chemical analysis of sample benchmark companion brown dwarfs whose primary star is type F, G or K. summarize the entire known these types systems, termed "compositional benchmarks", that are in literature recently published as key systems study order to best understand dwarf chemistry and condensate formation. Via mass balance stoichiometric calculations, we predict median atmospheric oxygen sink $17.8^{+1.7}_{-2.3}\%$ by utilizing stellar...
We report the identification of 89 new systems containing ultracool dwarf companions to main sequence stars and white dwarfs, using citizen science project Backyard Worlds: Planet 9 cross-reference between Gaia CatWISE2020. Thirty-two these thirty-three host were followed up with spectroscopic observations, companion spectral types ranging from M7-T9 G2-M9. These exhibit diverse characteristics, young old ages, blue very red morphologies, potential membership known moving groups, evidence...
We present the discovery of 13 new widely separated T dwarf companions to M primaries, identified using WISE/NEOWISE data by CatWISE and Backyard Worlds: Planet 9 projects. This sample represents a $\sim$60% increase in number known M+T systems, allows us probe most extreme products binary/planetary system formation, space made available CatWISE2020 catalog effort. Highlights among are WISEP J075108.79-763449.6, previously T9 thought be old due its SED, which we now find is part...