Alexey Goldin - Academia.edu (original) (raw)

Papers by Alexey Goldin

Universe

The transiting planet K2-18 b is one of the best candidates for a relatively nearby world harbori... more The transiting planet K2-18 b is one of the best candidates for a relatively nearby world harboring biological life. The long-term orbital evolution of this planet is investigated using theoretical and purely numerical techniques for two possible configurations: A single planet orbiting the host star, and a two-planet system including the proposed inner planet close to the 4:1 mean motion rationalization. The emphasis is made on the secular changes of eccentricity and orbital inclination, which are important for the climate stability of the planet. It is demonstrated that the secular orbital dynamics of planet K2-18 b with an internal companion are accurately represented by the periodic eccentricity and inclination exchange on the time scales of a few Kyr. A single planet is not expected to experience fast orbital changes, with the much weaker tidal and rotation-driven perturbations mostly reflecting in a slow periastron and nodal precession. The tidal decay of the orbit is too insi...

Astrophysical Journal Supplement Series, Nov 1, 2007

Taking advantage of an improved genetic optimization algorithm for fitting unconstrained Kepler o... more Taking advantage of an improved genetic optimization algorithm for fitting unconstrained Kepler orbits to the Hipparcos intermediate astrometric data, we obtain additional orbital solutions for 81 Hipparcos stars with previous stochastic (failed) solutions. The sample includes astrophysically interesting objects, including the old disk wide binary HIP 754, the nearby AGB star HIP 34922 (L 2 Pup), and the nearby M2 dwarf HIP 5496 (GJ 54, at 8 pc from the Sun), which has a resolved M dwarf companion.

Proceedings of SPIE, Oct 8, 2004

Bolocam is a millimetre-wave (1.1 and 2.1 mm) camera with an array of 119 bolometers. It has been... more Bolocam is a millimetre-wave (1.1 and 2.1 mm) camera with an array of 119 bolometers. It has been commissioned at the Caltech Submillimeter Observatory in Hawaii and is now in routine operation. Here we give an overview of the instrument and the data reduction pipeline. We discuss models of the sensitivity of Bolocam in different observing modes and under different atmospheric conditions. We briefly discuss observations of star-forming Galactic molecular clouds, a blank field survey for sub-millimeter galaxies, preliminary results of a blank-field CMB secondary anisotropy survey and discuss observations of galaxy clusters using the Sunyaev-Zel'dovich effect.

Monthly Notices of the Royal Astronomical Society, Apr 18, 2022

Celestial bodies approximated with rigid triaxial ellipsoids in a two-body system can rotate chao... more Celestial bodies approximated with rigid triaxial ellipsoids in a two-body system can rotate chaotically due to the time-varying gravitational torque from the central mass. At small orbital eccentricity values, rotation is short-term orderly and predictable within the commensurate spin-orbit resonances, while at eccentricity approaching unity, chaos completely takes over. Here, we present the full 3D rotational equations of motion around all three principle axes for triaxial minor planets and two independent methods of numerical solution based on Euler rotations and quaternion algebra. The domains of chaotic rotation are numerically investigated over the entire range of eccentricity with a combination of trial integrations of Euler's equations of motion and the GALI(k) method. We quantify the dependence of the order-chaos boundaries on shape by changing a prolateness parameter, and find that the main 1:1 spin-orbit resonance disappears for specific moderately prolate shapes already at eccentricities as low as 0.3. The island of short-term stability around the main 1:1 resonance shrinks with increasing eccentricity at a fixed low degree of prolateness and completely vanishes at approximately 0.8. This island is also encroached by chaos on longer time scales indicating longer Lyapunov exponents. Trajectories in the close vicinity of the 3:2 spin-orbit resonance become chaotic at smaller eccentricities, but separated enclaves of orderly rotation emerge at eccentricities as high as 0.8. Initial perturbations of rotational velocity in latitude away from the exact equilibrium result in a spectrum of free libration, nutation, and polar wander, which is not well matched by the linearized analysis omitting the inertial terms.

The Astrophysical Journal, Oct 20, 1997

AAS/Division of Dynamical Astronomy Meeting, Aug 3, 2020

The Astrophysical Journal, 1997

The Astrophysical Journal, 2000

Astronomy Letters, Mar 1, 1994

Description: Data was taken between January and February, 2003. Flux units are in mJy per 31 arcs... more Description: Data was taken between January and February, 2003. Flux units are in mJy per 31 arcsecond beam. Telescope Information Caltech Submillimeter Observatory Status: Final Sampling: Sensitivity: 1 sigma rms = 15 mJy per beam Waveband: 1120 microns Resolution: 31 arcsecond beam in 10 arcsecond pixels (diffuse large-scale structure is lost) Areal Coverage: 7.5 square degrees Map Center (Galactic): NA NA Map Center (J2000): RA = 03:36:00 Dec = 31:17:00

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006

The Planetary Science Journal, 2021

Few solar system asteroids and comets are found in high-eccentricity orbits (e > 0.9), but in ... more Few solar system asteroids and comets are found in high-eccentricity orbits (e > 0.9), but in the primordial planetesimal disks and in exoplanet systems around dying stars such objects are believed to be common. For 2006 HY51, the main belt asteroid with the highest known eccentricity 0.9684, we investigate the probable rotational states today using our computer-efficient chaotic process simulation method. Starting with random initial conditions, we find that this asteroid is inevitably captured into stable spin–orbit resonances typically within tens to a hundred megayears. The resonances are confirmed by direct integration of the equation of motion in the vicinity of endpoints. Most resonances are located at high spin values above 960 times the mean motion (such as 964:1 or 4169:4), corresponding to rotation periods of a few days. We discover three types of resonance in the high-eccentricity regime: (1) regular circulation with weakly librating aphelion velocities and integer-nu...

arXiv: Solar and Stellar Astrophysics, 2020

KIC 5773205 is the least luminous eclipsing M dwarf found in the Villanova catalog of eclipsing b... more KIC 5773205 is the least luminous eclipsing M dwarf found in the Villanova catalog of eclipsing binaries detected by the {\it Kepler} mission. We processed and analyzed the three available quarters of mission data for this star and discovered a persistent periodic variation of the light curve with a period, which is in exact 4:5 commensurability to the orbital period. Three routes of interpretation are considered: 1) non-radial pulsations excited by the tidal interaction at a specific eigenfrequency; 2) a high-order spin-orbit resonance caused by the tides; 3) an ellipsoidal deformation caused by an outer orbiting companion in a mean motion resonance. All three explanations meet considerable difficulties, but the available facts seem to favor the tidally driven pulsation scenario. The star may represent a new type of heartbeat binary with tidally excited pulsations that are close to the orbital motion in frequency.

The Astrophysical Journal

The Astrophysical Journal

The Astrophysical Journal Supplement Series

Variability induced motion (VIM) is an observable effect in simultaneous astrometric and photomet... more Variability induced motion (VIM) is an observable effect in simultaneous astrometric and photometric measurements caused by brightness variation in one of the components of a double source or blended image, which manifests itself as a strongly correlated shift of the optical photocenter. We have processed the entire collection of the Kepler long-cadence light curve data looking for correlated signals in astrometry and photometry on the time basis of a quarter year. Limiting the VIM correlation coefficient to 0.3, VIM events are detected for 129 525 Kepler stars at least in one quarter. Of 7305 Kepler objects of interest (KOI), 4440 are detected as VIM at least once. Known variable stars and resolved double stars have elevated rates of VIM detection. Confident VIM occurrences are found for stars with suggested superflare events, indicating possible signal contamination. We present a complete catalog of all quarterly VIM detections. This catalog should be checked for such astrophysically significant events as transits of exoplanets, new eclipsing stars, and superflares of solar-type stars.

The Astrophysical Journal

ABSTRACT We are developing a single pixel antenna coupled bolometric detector as a precursor to t... more ABSTRACT We are developing a single pixel antenna coupled bolometric detector as a precursor to the SAMBA (Superconducting Antenna-coupled Multi-frequency Bolometric Array) instrument. Our device consists of a dual slot microstrip antenna coupled to an Al/Ti/Au voltage-biased transition edge superconducting bolometer (TES). The coupling architecture involves propagating the signal along superconducting microstrip lines and terminating the lines at a normal metal resistor on a thermally isolated island. The device, which is inherently polarization sensitive, is optimized to for 100GHz band measurements, ideal for future implementation as an astronomical sub-millimeter instrument. We will present recent tests of these single pixel detectors.

Universe

The transiting planet K2-18 b is one of the best candidates for a relatively nearby world harbori... more The transiting planet K2-18 b is one of the best candidates for a relatively nearby world harboring biological life. The long-term orbital evolution of this planet is investigated using theoretical and purely numerical techniques for two possible configurations: A single planet orbiting the host star, and a two-planet system including the proposed inner planet close to the 4:1 mean motion rationalization. The emphasis is made on the secular changes of eccentricity and orbital inclination, which are important for the climate stability of the planet. It is demonstrated that the secular orbital dynamics of planet K2-18 b with an internal companion are accurately represented by the periodic eccentricity and inclination exchange on the time scales of a few Kyr. A single planet is not expected to experience fast orbital changes, with the much weaker tidal and rotation-driven perturbations mostly reflecting in a slow periastron and nodal precession. The tidal decay of the orbit is too insi...

Astrophysical Journal Supplement Series, Nov 1, 2007

Taking advantage of an improved genetic optimization algorithm for fitting unconstrained Kepler o... more Taking advantage of an improved genetic optimization algorithm for fitting unconstrained Kepler orbits to the Hipparcos intermediate astrometric data, we obtain additional orbital solutions for 81 Hipparcos stars with previous stochastic (failed) solutions. The sample includes astrophysically interesting objects, including the old disk wide binary HIP 754, the nearby AGB star HIP 34922 (L 2 Pup), and the nearby M2 dwarf HIP 5496 (GJ 54, at 8 pc from the Sun), which has a resolved M dwarf companion.

Proceedings of SPIE, Oct 8, 2004

Bolocam is a millimetre-wave (1.1 and 2.1 mm) camera with an array of 119 bolometers. It has been... more Bolocam is a millimetre-wave (1.1 and 2.1 mm) camera with an array of 119 bolometers. It has been commissioned at the Caltech Submillimeter Observatory in Hawaii and is now in routine operation. Here we give an overview of the instrument and the data reduction pipeline. We discuss models of the sensitivity of Bolocam in different observing modes and under different atmospheric conditions. We briefly discuss observations of star-forming Galactic molecular clouds, a blank field survey for sub-millimeter galaxies, preliminary results of a blank-field CMB secondary anisotropy survey and discuss observations of galaxy clusters using the Sunyaev-Zel'dovich effect.

Monthly Notices of the Royal Astronomical Society, Apr 18, 2022

Celestial bodies approximated with rigid triaxial ellipsoids in a two-body system can rotate chao... more Celestial bodies approximated with rigid triaxial ellipsoids in a two-body system can rotate chaotically due to the time-varying gravitational torque from the central mass. At small orbital eccentricity values, rotation is short-term orderly and predictable within the commensurate spin-orbit resonances, while at eccentricity approaching unity, chaos completely takes over. Here, we present the full 3D rotational equations of motion around all three principle axes for triaxial minor planets and two independent methods of numerical solution based on Euler rotations and quaternion algebra. The domains of chaotic rotation are numerically investigated over the entire range of eccentricity with a combination of trial integrations of Euler's equations of motion and the GALI(k) method. We quantify the dependence of the order-chaos boundaries on shape by changing a prolateness parameter, and find that the main 1:1 spin-orbit resonance disappears for specific moderately prolate shapes already at eccentricities as low as 0.3. The island of short-term stability around the main 1:1 resonance shrinks with increasing eccentricity at a fixed low degree of prolateness and completely vanishes at approximately 0.8. This island is also encroached by chaos on longer time scales indicating longer Lyapunov exponents. Trajectories in the close vicinity of the 3:2 spin-orbit resonance become chaotic at smaller eccentricities, but separated enclaves of orderly rotation emerge at eccentricities as high as 0.8. Initial perturbations of rotational velocity in latitude away from the exact equilibrium result in a spectrum of free libration, nutation, and polar wander, which is not well matched by the linearized analysis omitting the inertial terms.

The Astrophysical Journal, Oct 20, 1997

AAS/Division of Dynamical Astronomy Meeting, Aug 3, 2020

The Astrophysical Journal, 1997

The Astrophysical Journal, 2000

Astronomy Letters, Mar 1, 1994

Description: Data was taken between January and February, 2003. Flux units are in mJy per 31 arcs... more Description: Data was taken between January and February, 2003. Flux units are in mJy per 31 arcsecond beam. Telescope Information Caltech Submillimeter Observatory Status: Final Sampling: Sensitivity: 1 sigma rms = 15 mJy per beam Waveband: 1120 microns Resolution: 31 arcsecond beam in 10 arcsecond pixels (diffuse large-scale structure is lost) Areal Coverage: 7.5 square degrees Map Center (Galactic): NA NA Map Center (J2000): RA = 03:36:00 Dec = 31:17:00

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006

The Planetary Science Journal, 2021

Few solar system asteroids and comets are found in high-eccentricity orbits (e > 0.9), but in ... more Few solar system asteroids and comets are found in high-eccentricity orbits (e > 0.9), but in the primordial planetesimal disks and in exoplanet systems around dying stars such objects are believed to be common. For 2006 HY51, the main belt asteroid with the highest known eccentricity 0.9684, we investigate the probable rotational states today using our computer-efficient chaotic process simulation method. Starting with random initial conditions, we find that this asteroid is inevitably captured into stable spin–orbit resonances typically within tens to a hundred megayears. The resonances are confirmed by direct integration of the equation of motion in the vicinity of endpoints. Most resonances are located at high spin values above 960 times the mean motion (such as 964:1 or 4169:4), corresponding to rotation periods of a few days. We discover three types of resonance in the high-eccentricity regime: (1) regular circulation with weakly librating aphelion velocities and integer-nu...

arXiv: Solar and Stellar Astrophysics, 2020

KIC 5773205 is the least luminous eclipsing M dwarf found in the Villanova catalog of eclipsing b... more KIC 5773205 is the least luminous eclipsing M dwarf found in the Villanova catalog of eclipsing binaries detected by the {\it Kepler} mission. We processed and analyzed the three available quarters of mission data for this star and discovered a persistent periodic variation of the light curve with a period, which is in exact 4:5 commensurability to the orbital period. Three routes of interpretation are considered: 1) non-radial pulsations excited by the tidal interaction at a specific eigenfrequency; 2) a high-order spin-orbit resonance caused by the tides; 3) an ellipsoidal deformation caused by an outer orbiting companion in a mean motion resonance. All three explanations meet considerable difficulties, but the available facts seem to favor the tidally driven pulsation scenario. The star may represent a new type of heartbeat binary with tidally excited pulsations that are close to the orbital motion in frequency.

The Astrophysical Journal

The Astrophysical Journal

The Astrophysical Journal Supplement Series

Variability induced motion (VIM) is an observable effect in simultaneous astrometric and photomet... more Variability induced motion (VIM) is an observable effect in simultaneous astrometric and photometric measurements caused by brightness variation in one of the components of a double source or blended image, which manifests itself as a strongly correlated shift of the optical photocenter. We have processed the entire collection of the Kepler long-cadence light curve data looking for correlated signals in astrometry and photometry on the time basis of a quarter year. Limiting the VIM correlation coefficient to 0.3, VIM events are detected for 129 525 Kepler stars at least in one quarter. Of 7305 Kepler objects of interest (KOI), 4440 are detected as VIM at least once. Known variable stars and resolved double stars have elevated rates of VIM detection. Confident VIM occurrences are found for stars with suggested superflare events, indicating possible signal contamination. We present a complete catalog of all quarterly VIM detections. This catalog should be checked for such astrophysically significant events as transits of exoplanets, new eclipsing stars, and superflares of solar-type stars.

The Astrophysical Journal

ABSTRACT We are developing a single pixel antenna coupled bolometric detector as a precursor to t... more ABSTRACT We are developing a single pixel antenna coupled bolometric detector as a precursor to the SAMBA (Superconducting Antenna-coupled Multi-frequency Bolometric Array) instrument. Our device consists of a dual slot microstrip antenna coupled to an Al/Ti/Au voltage-biased transition edge superconducting bolometer (TES). The coupling architecture involves propagating the signal along superconducting microstrip lines and terminating the lines at a normal metal resistor on a thermally isolated island. The device, which is inherently polarization sensitive, is optimized to for 100GHz band measurements, ideal for future implementation as an astronomical sub-millimeter instrument. We will present recent tests of these single pixel detectors.