Search Publications
Simultaneous High Dynamic Range Algorithm, Testing, and Instrument Simulation
Chamberlin, Phillip C.; Jin, Meng; Woods, Thomas N. +4 more
Within an imaging instrument's field of view, there may be many observational targets of interest. Similarly, within a spectrograph's bandpass, there may be many emission lines of interest. The brightness of these targets and lines can be orders of magnitude different, which poses a challenge to instrument and mission design. A single exposure can…
LEGA-C: Analysis of Dynamical Masses from Ionized Gas and Stellar Kinematics at z 0.8
Bell, Eric F.; D'Eugenio, Francesco; Franx, Marijn +12 more
We compare dynamical mass estimates based on spatially extended stellar and ionized gas kinematics (M dyn,* and M dyn,eml, respectively) of 157 star-forming galaxies at 0.6 ≤ z < 1. Compared with z ~ 0, these galaxies have enhanced star formation rates, with stellar feedback likely affecting the dynamics of the gas. We us…
Investigation of Rocket Effect in BRC 18 using Gaia EDR3
Ojha, D. K.; Saha, Piyali; Neha, Sharma +1 more
Bright-rimmed clouds (BRCs) are ideal candidates to study radiation-driven implosion mode of star formation as they are potential sites of triggered star formation, located at the edges of HII regions, showing evidence of ongoing star formation processes. BRC 18 is located towards the eastern edge of relatively closer (~400 pc) H II region excited…
Comparison of Two Methods for Calculating Magnetic Helicity in the Solar Corona
Zhang, Mei; Yang, Shangbin; Yang, Xiao +1 more
Duo to the large magnetic Reynolds number, the magnetic helicity originating from the solar interior can be carried away through the photosphere into the corona. However, the relationship between the accumulated magnetic helicity flux through the photosphere and the magnetic helicity in the corona is still unclear. By selecting 36 newly emerging a…
Selecting a complete sample of blazars in sub-millimetre catalogues
Bonavera, L.; González-Nuevo, J.; López-Caniego, M. +6 more
The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS), which has covered about 642 sq. deg. in five bands from 100 to 500 $\mu \rm m$, allows a blind flux-limited selection of blazars at sub-mm wavelengths. However, blazars constitute a tiny fraction of H-ATLAS sources and therefore identifying them is not a trivial task. Using the data…
Spectral Variability of the Born-again Ejecta in A 58
Toalá, Jesús A.; Guerrero, Martín A.; Rodríguez-González, Janis B. +1 more
Born-again planetary nebulae (PNs) allow investigating stellar evolution, dust production, and nebular shocks in human timescales. Here we present an analysis of multiepoch optical spectroscopic observations of the born-again PN A 58 around V605 Aql, which experienced a very late thermal pulse about a century ago. The H-deficient ejecta has experi…
Investigating the nature and properties of MAXI J1810-222 with radio and X-ray observations
Pinto, C.; Motta, S. E.; Segreto, A. +10 more
We present results from radio and X-ray observations of the X-ray transient MAXI J1810-222. The nature of the accretor in this source has not been identified. In this paper, we show results from a quasi-simultaneous radio and X-ray monitoring campaign taken with the Australia Telescope Compact Array, the Neil Gehrels Swift Observatory X-ray Telesc…
Visual Orbits of Spectroscopic Binaries with the CHARA Array. IV. HD 61859, HD 89822, HD 109510, and HD 191692
Gies, Douglas R.; Lester, Kathryn V.; Monnier, John D. +18 more
We present the visual orbits of four spectroscopic binary stars, HD 61859, HD 89822, HD 109510, and HD 191692, using long baseline interferometry with the CHARA Array. We also obtained new radial velocities from echelle spectra using the APO 3.5 m, CTIO 1.5 m, and Fairborn Observatory 2.0 m telescopes. By combining the astrometric and spectroscopi…
The Helicity Sign of Flux Transfer Event Flux Ropes and Its Relationship to the Guide Field and Hall Physics in Magnetic Reconnection at the Magnetopause
Lavraud, B.; Génot, V.; Chen, Y. +13 more
Flux Transfer Events (FTEs) are transient magnetic flux ropes typically found at the Earth's magnetopause on the dayside. While it is known that FTEs are generated by magnetic reconnection, it remains unclear how the details of magnetic reconnection controls their properties. A recent study showed that the helicity sign of FTEs positively correlat…
Spectroscopic analysis of BPS CS 22940-0009: connecting evolved helium stars
Jeffery, C. S.; Woolf, V. M.; Snowdon, E. J. +1 more
BPS CS 22940-0009 is a helium-rich B-star that shares characteristics with both helium-rich B subdwarfs and extreme helium stars. The optical spectrum of BPS CS 22940-0009 has been analysed from SALT observations. The atmospheric parameters were found to be $T_{\rm eff} = 34\, 970 \pm 370$ K, $\log g/{\rm cm\, s^{-2}} = 4.79 \pm 0.17$, nH