Per Calissendorff
A5019793138- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Spectroscopy and Laser Applications
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Space Science and Extraterrestrial Life
- Spectroscopy Techniques in Biomedical and Chemical Research
- History and Developments in Astronomy
- Laser-induced spectroscopy and plasma
- High-pressure geophysics and materials
- SAS software applications and methods
- Calibration and Measurement Techniques
- Atmospheric Ozone and Climate
- Pulsars and Gravitational Waves Research
- Evolutionary Game Theory and Cooperation
University of Michigan
2022-2024
Stockholm University
2015-2022
Michigan United
2022
AlbaNova
2015-2018
Max Planck Institute for Astronomy
2018
Max Planck Society
2018
We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is $<$20 M$_\mathrm{Jup}$ widely separated ($\sim$8\arcsec, = 150 au), young, companion that shares photometric colors and spectroscopic features with directly imaged exoplanets HR 8799 c, d, e. As an L-to-T transition object, exists along region color-magnitude diagram where substellar atmospheres from cloudy clear. observed 1256~b \textit{JWST}'s NIRSpec IFU MIRI MRS modes for coverage 1 $\mu$m 20 at...
We present JWST Early Release Science (ERS) coronagraphic observations of the super-Jupiter exoplanet, HIP 65426 b, with Near-Infrared Camera (NIRCam) from 2-5 $\mu$m, and Mid-Infrared Instrument (MIRI) 11-16 $\mu$m. At a separation $\sim$0.82" (86$^{+116}_{-31}$ au), b is clearly detected in all seven our observational filters, representing first images an exoplanet to be obtained by JWST, ever direct detection beyond 5 These demonstrate that exceeding its nominal predicted performance up...
Abstract The unprecedented medium-resolution ( R λ ∼ 1500–3500) near- and mid-infrared (1–18 μ m) spectrum provided by JWST for the young (140 ± 20 Myr) low-mass (12–20 M Jup ) L–T transition (L7) companion VHS 1256 b gives access to a catalog of molecular absorptions. In this study, we present comprehensive analysis data set utilizing forward-modeling approach applying our Bayesian framework, ForMoSA . We explore five distinct atmospheric models assess their performance in estimating key...
Abstract We report the discovery of first brown dwarf binary system with a Y primary, WISE J033605.05−014350.4, observed NIRCam on JWST F150W and F480M filters. employed an empirical point-spread function model to identify companion, located at projected separation 0.″084, position angle 295°, contrasts 2.8 1.8 mag in F480M, respectively. At distance 10 pc based its Spitzer parallax, assuming random inclination distribution, physical is approximately 1 au. Evolutionary models predict for...
Abstract The determination of the astrophysical properties stars remains challenging and frequently relies on application stellar models. Stellar sequences in nearby open clusters provide some best means to test calibrate evolutionary models isochrones use these assign consistently a large sample stars. We aim at updating single-star sequence members Hyades cluster, identifying best-fitting isochrones, determining Gaia Catalog Nearby Stars provides comprehensive high-probability cluster....
Abstract We present a performance analysis for the aperture masking interferometry (AMI) mode on board James Webb Space Telescope Near Infrared Imager and Slitless Spectrograph (JWST/NIRISS). Thanks to self-calibrating observables, AMI accesses inner working angles down even within classical diffraction limit. The scientific potential of this has recently been demonstrated by Early Release Science (ERS) 1386 program with deep search close-in companions in HIP 65426 exoplanetary system. As...
If advanced extraterrestrial civilizations choose to construct vast numbers of Dyson spheres harvest radiation energy, this could affect the characteristics their host galaxies. Potential signatures such astroengineering projects include reduced optical luminosity, boosted infrared luminosity and morphological anomalies. Here, we apply a technique pioneered by Annis (1999) search for Kardashev type III in disk galaxies, based on predicted offset these galaxies from Tully-Fisher relation. By...
Abstract High-contrast imaging of debris disk systems permits us to assess the composition and size distribution circumstellar dust, probe recent dynamical histories, directly detect characterize embedded exoplanets. Observations these in infrared beyond 2–3 μ m promise access both extremely favorable planet contrasts numerous scattered-light spectral features—but have typically been inhibited by brightness sky at wavelengths. We present coronagraphy AU Microscopii (AU Mic) system using...
Abstract We present aperture masking interferometry (AMI) observations of the star HIP 65426 at 3.8 μ m, as part JWST Direct Imaging Early Release Science program, obtained using Near Infrared Imager and Slitless Spectrograph instrument. This mode provides access to very small inner working angles (even separations slightly below Michelson limit 0.5 λ / D for an interferometer), which are inaccessible with classical coronagraphs. When combined JWST’s unprecedented infrared sensitivity, this...
ABSTRACT The study of cosmology, galaxy formation, and exoplanets has now advanced to a stage where cosmic inventory terrestrial planets (TPs) may be attempted. By coupling semianalytic models formation recipe that relates the occurrence mass metallicity their host stars, we trace population TPs around both solar-mass (FGK type) lower-mass (M dwarf) stars throughout all history. We find mean age in local universe is <?CDATA $7\pm 1\,\mathrm{Gyr}$?> for FGK hosts $8\pm M dwarfs. estimate hot...
The relationship between luminosity and mass is of fundamental importance for direct imaging studies brown dwarf planetary companions to stars. In principle this can be inferred from theoretical mass-luminosity models; however, these relations have not yet been thoroughly calibrated, since there a lack substellar which both the brightness directly measured. One notable exception GJ 758 B, companion in $\sim$20 AU orbit around nearby Sun-like star, has imaged dynamically detected through...
Context . Brown dwarfs in the spectral range L9–T3.5, within so called L/T transition, have been shown to be variable at higher amplitudes and with greater frequency than other field dwarfs. This strong variability allows for probing of their atmospheric structure 3D through multi-wavelength observations studying underlying physical mechanisms responsible variability. The few known strongly this extensively studied. Now, more variables such as these need discovered studied better constrain...
The number of supernovae known to be connected with long-duration gamma-ray bursts is increasing and the link between these events no longer exclusively found at low redshift ($z \lesssim 0.3$) but well established also larger distances. We present a new case such liaison $z = 0.33$ GRB\,171010A SN\,2017htp. It second closest GRB an associated supernova only three detected by Fermi-LAT. one few higher cases where spectroscopic observations were possible shows spectral similarities...
Based on GAIA EDR3, we revisit and update our sample of bonafide single stars in the Hyades open cluster. The small observational uncertainties parallax photometry EDR3 result a tightly defined stellar sequence, which is ideal for testing calibration theoretical evolutionary tracks isochrones. We benchmark solar-scaled MESA models against star sequence. find that non-rotating [Fe/H] = +0.25 provide good fit with masses above 0.85, very low mass below 0.25 M$_\odot$. For between 0.85...
Brown dwarfs lack nuclear fusion and cool with time; the coldest known have an effective temperature below 500 K, are as Y dwarfs. We present a James Webb Space Telescope (JWST) photometric dataset of dwarfs: twenty-three were imaged in wide-field mode, 20 using NIRCam F150W F480M filters, 3 NIRISS filter. vs. $-$ color-magnitude diagram for our sample, other brown colors synthesized from JWST spectra by Beiler et al. (2024). For one target, WISEA J083011.95$+$283716.0, its detection...
Abstract Brown dwarfs lack nuclear fusion and cool with time; the coldest known have an effective temperature below 500 K, are as Y dwarfs. We present a James Webb Space Telescope (JWST) photometric data set of dwarfs: 23 were imaged in wide-field mode, 20 using NIRCam F150W F480M filters, three NIRISS filter. versus – color–magnitude diagram for our sample, other brown colors synthesized from JWST spectra by S. A. Beiler et al. For one target, WISEA J083011.95+283716.0, its detection...
Binary stars constitute a large percentage of the stellar population, yet relatively little is known about planetary systems orbiting them. Most constraints on circumbinary planets (CBPs) so far come from transit observations with Kepler telescope, which sensitive to close-in exoplanets but does not constrain wider orbits. However, continuous developments in high-contrast imaging techniques, this population can now be addressed through direct imaging. We present full survey results Search...
Context. The Gaia astrophysical parameters inference system (Apsis) provides parameter estimates for several to hundreds of millions stars. Aims. We aim benchmark DR3 Apsis. Methods. compiled approximately 1500 bona fide single stars in the Hyades and Pleiades open clusters validation PARSEC isochrones, comparison with Apsis estimates. stellar isochrones photometric enable us assign average ages metallicities clusters, mass, effective temperature, luminosity, surface gravity individual...
Abstract Observations of debris disks offer important insights into the formation and evolution planetary systems. Though M dwarfs make up approximately 80% nearby stars, very few dwarf have been studied in detail—making it unclear how or if information gleaned from studying around more massive stars extends to abundant We report first scattered-light detection disk M4 star Fomalhaut C using JWST's Near Infrared Camera (NIRCam; 3.6 4.4 μ m). This result adds prior sample only four with...
We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is $<$20 M$_\mathrm{Jup}$ widely separated ($\sim$8\arcsec, = 150 au), young, companion that shares photometric colors and spectroscopic features with directly imaged exoplanets HR 8799 c, d, e. As an L-to-T transition object, exists along region color-magnitude diagram where substellar atmospheres from cloudy clear. observed 1256~b \textit{JWST}'s NIRSpec IFU MIRI MRS modes for coverage 1 $μ$m 20 at...
Abstract The detection of emission lines associated with accretion processes is a direct method for studying how and where gas giant planets form, young interact their natal protoplanetary disk, volatile delivery to atmosphere takes place. H α ( λ = 0.656 μ m) expected be the strongest line observable from ground adaptive optics systems, therefore target specific high-contrast imaging campaigns. We present MagAO-X Hubble Space Telescope (HST) data obtained search previously detected...
We combine new Lucky Imaging astrometry from NTT/AstraLux Sur with already published the AstraLux Large M-dwarf Multiplicity Survey to compute orbital elements and individual masses of 2MASS J10364483+1521394 triple system belonging Ursa-Major moving group. The consists one primary low-mass orbited by two less massive companions, for which we determine a combined dynamical mass $M_{\rm{B}+\rm{C}}= 0.48 \pm 0.14\ M_\odot$. show companions relative motions that they are equal (with ratio $1.00...
ABSTRACT We search for additional companions in the GJ 367 exoplanet system and aim to better constrain its age evolutionary status. analyse high-contrast direct imaging observations obtained with HST/NICMOS, VLT/NACO, VLT/SPHERE. investigate critically discuss conflicting indicators based on theoretical isochrones models Galactic dynamics. A comparison of GAIA EDR3 parallax photometric measurements suggests a young ≤60 Myr 367. The star’s kinematics exclude membership any nearby moving...
Young M-type binaries are particularly useful for precise isochronal dating by taking advantage of their extended pre-main sequence evolution. Orbital monitoring these low-mass objects becomes essential in constraining fundamental properties, as dynamical masses can be extracted from Keplerian motion. Here, we present the combined efforts AstraLux Large Multiplicity Survey, together with a filler sub-programme SpHere INfrared Exoplanet (SHINE) project and previously unpublished data FastCam...