Search Publications
A Quick Guide to Nearby Young Associations
Gagné, Jonathan
Nearby associations of stars which are coeval are important benchmark laboratories because they provide robust measurements of stellar ages. The study of such coeval groups makes it possible to better understand star formation by studying the initial mass function, the binary fraction or the circumstellar disks of stars, to determine how the initi…
An Infrared Census of R Coronae Borealis Stars II—Spectroscopic Classifications and Implications for the Rate of Low-mass White Dwarf Mergers
Soria, Roberto; Clayton, Geoffrey C.; De, Kishalay +18 more
We present results from a systematic infrared (IR) census of R Coronae Borealis (RCB) stars in the Milky Way, using data from the Palomar Gattini IR (PGIR) survey. RCB stars are dusty, erratic variable stars presumably formed from the merger of a He-core and a CO-core white dwarf (WD). PGIR is a 30 cm J-band telescope with a 25 deg2 cam…
Validation of Gaia DR3 Orbital and Acceleration Solutions with Hierarchical Triples
El-Badry, Kareem; Nagarajan, Pranav
Using data from Gaia DR3, we construct a sample of 14,791 gravitationally bound wide pairs in which one of the components is an unresolved binary with an astrometric orbital or acceleration solution. These systems are hierarchical triples, with inner binary separations of order 1 au, and outer separations of 100–100,000 au. Leveraging the fact tha…
An Algorithm to Mitigate Charge Migration Effects in Data from the Near Infrared Imager and Slitless Spectrograph on the James Webb Space Telescope
Volk, Kevin; Bushouse, Howard; Goudfrooij, Paul +1 more
We present an algorithm that mitigates the effects of charge migration due to the "brighter-fatter effect" (BFE) that occurs for highly illuminated stars in the Teledyne HAWAII-2RG detectors used in the NIRCam, NIRISS, and NIRSpec science instruments aboard the James Webb Space Telescope (JWST). The impact of this effect is most significant for ph…
The Companion Mass Distribution of Post Common Envelope Hot Subdwarf Binaries: Evidence for Boosted and Disrupted Magnetic Braking?
El-Badry, Kareem; Nagarajan, Pranav; van Roestel, Jan +6 more
We measure the mass distribution of main-sequence (MS) companions to hot subdwarf B stars (sdBs) in post-common envelope binaries (PCEBs). We carried out a spectroscopic survey of 14 eclipsing systems ("HW Vir binaries") with orbital periods of 3.8 < Porb < 12 hr, resulting in a well-understood selection function and a near-comple…
A Suite of Classical Cepheids Tied to the Binary Cluster Berkeley 58 and NGC 7790
Majaess, Daniel; Turner, David G.
The classical Cepheids CE Cas A, CE Cas B, CF Cas, and CG Cas are likely members of the binary open cluster comprising NGC 7790 and Berkeley 58. The clusters are of comparable age and in close proximity, as deduced from differentially dereddened UuB P BVGR P photometry, and Cepheid period-age relations. Gaia DR3 astrometr…
JWST's PEARLS: Improved Flux Calibration for NIRCam
Grogin, Norman A.; Hathi, Nimish P.; Koekemoer, Anton M. +23 more
The Prime Extragalactic Areas for Reionization and Lensing Science, a James Webb Space Telescope (JWST) GTO program, obtained a set of unique NIRCam observations that have enabled us to significantly improve the default photometric calibration across both NIRCam modules. The observations consisted of three epochs of 4-band (F150W, F200W, F356W, an…
Toward Exoplanet Transit Spectroscopy Using JWST/MIRI's Medium Resolution Spectrometer
Deming, Drake; Lustig-Yaeger, Jacob; Fu, Guangwei +9 more
The Mid-Infrared Instrument Medium Resolution Spectrometer (the MRS) on JWST has potentially important advantages for transit and eclipse spectroscopy of exoplanets, including lack of saturation for bright host stars, wavelength span to longward of 20 µm, and JWST's highest spectral resolving power. We here test the performance of the MRS for time…
Astrometry as a Tool for Discovering and Weighing Faint Companions to Nearby Stars
Brandt, Timothy D.
This tutorial covers the use of absolute astrometry, in particular from the combination of the Hipparcos and Gaia missions, to identify faint companions to nearby stars and to measure the masses and orbits of those companions. Absolute astrometry has been used with increasing success to discover new planets and brown dwarfs and to measure masses a…
Near-Earth Object Observations using Synthetic Tracking
Zhai, Chengxing; Shao, Michael; Choi, Philip +5 more
Synthetic tracking (ST) has emerged as a potent technique for observing fast-moving near-Earth objects (NEOs), offering enhanced detection sensitivity and astrometric accuracy by avoiding trailing loss. This approach also empowers small telescopes to use prolonged integration times to achieve high sensitivity for NEO surveys and follow-up observat…