Astronomy and Planetary Science Thread

Photometric properties and stellar parameters of the rapidly rotating magnetic early-B star HD 345439

We first present the multicolor photometry results of the rapidly rotating magnetic star HD 345439 using the Nanshan One-meter Wide-field Telescope. From the photometric observations, we derive a rotational period of 0.7699\pm0.0014 day. The light curves of HD 345439 are dominated by the double asymmetric S-wave feature that arises from the magnetic clouds. Pulsating behaviors are not observed in Sector 41 of the Transiting Exoplanet Survey Satellite. No evidence is found of the occurrence of centrifugal breakout events neither in the residual flux nor in the systematic variations at the extremum of the light curve. Based on the hypothesis of the Rigidly Rotating Magnetosphere model, we restrict the magnetic obliquity angle {β} and the rotational inclination angle i so that they satisfy the approximate relation {β+i≈105∘}. The colour excess, extinction, and luminosity are determined to be E(B−V)=0.745±0.016mag, AV=2.31±0.05mag, and log(L/L⊙)=3.82±0.1dex, respectively. Furthermore, we derive the effective temperature as Teff=22±1kK and the surface gravity as logg=4.00±0.22. The massM=7.24+1.75−1.24M⊙, radiusR=4.44+2.68−1.93R⊙, and ageτage=23.62+4.24−21.97Myr are estimated from the Hertzsprung--Russell Diagram

 
Near of course being a relative term here.

A Sun-like star orbiting a black hole

Abstract
We report discovery of a bright, nearby (⁠G=13.8;d=480pc
⁠) Sun-like star orbiting a dark object. We identified the system as a black hole candidate via its astrometric orbital solution from the Gaia mission. Radial velocities validated and refined the Gaia solution, and spectroscopy ruled out significant light contributions from another star. Joint modeling of radial velocities and astrometry constrains the companion mass to M2 = 9.62 ± 0.18 M⊙. The spectroscopic orbit alone sets a minimum companion mass of M2 > 5 M⊙; if the companion were a 5 M⊙ star, it would be 500 times more luminous than the entire system. These constraints are insensitive to the mass of the luminous star, which appears as a slowly-rotating G dwarf (⁠Teff=5850K
⁠, log g = 4.5, M = 0.93 M⊙), with near-solar metallicity (⁠[Fe/H]=−0.2
⁠) and an unremarkable abundance pattern. We find no plausible astrophysical scenario that can explain the orbit and does not involve a black hole. The orbital period, Porb = 185.6 days, is longer than that of any known stellar-mass black hole binary. The system’s modest eccentricity (e = 0.45), high metallicity, and thin-disk Galactic orbit suggest that it was born in the Milky Way disk with at most a weak natal kick. How the system formed is uncertain. Common envelope evolution can only produce the system’s wide orbit under extreme and likely unphysical assumptions. Formation models involving triples or dynamical assembly in an open cluster may be more promising. This is the nearest known black hole by a factor of 3, and its discovery suggests the existence of a sizable population of dormant black holes in binaries. Future Gaia releases will likely facilitate the discovery of dozens more.

academic.oup.com

A Sun-like star orbiting a black hole

ABSTRACT. We report discovery of a bright, nearby ($G = 13.8;\, \, d = 480\, \rm pc$) Sun-like star orbiting a dark object. We identified the system as a black
academic.oup.com academic.oup.com
 
Flyaway said:
Near of course being a relative term here.

A Sun-like star orbiting a black hole

Abstract
We report discovery of a bright, nearby (⁠G=13.8;d=480pc
⁠) Sun-like star orbiting a dark object. We identified the system as a black hole candidate via its astrometric orbital solution from the Gaia mission. Radial velocities validated and refined the Gaia solution, and spectroscopy ruled out significant light contributions from another star. Joint modeling of radial velocities and astrometry constrains the companion mass to M2 = 9.62 ± 0.18 M⊙. The spectroscopic orbit alone sets a minimum companion mass of M2 > 5 M⊙; if the companion were a 5 M⊙ star, it would be 500 times more luminous than the entire system. These constraints are insensitive to the mass of the luminous star, which appears as a slowly-rotating G dwarf (⁠Teff=5850K
⁠, log g = 4.5, M = 0.93 M⊙), with near-solar metallicity (⁠[Fe/H]=−0.2
⁠) and an unremarkable abundance pattern. We find no plausible astrophysical scenario that can explain the orbit and does not involve a black hole. The orbital period, Porb = 185.6 days, is longer than that of any known stellar-mass black hole binary. The system’s modest eccentricity (e = 0.45), high metallicity, and thin-disk Galactic orbit suggest that it was born in the Milky Way disk with at most a weak natal kick. How the system formed is uncertain. Common envelope evolution can only produce the system’s wide orbit under extreme and likely unphysical assumptions. Formation models involving triples or dynamical assembly in an open cluster may be more promising. This is the nearest known black hole by a factor of 3, and its discovery suggests the existence of a sizable population of dormant black holes in binaries. Future Gaia releases will likely facilitate the discovery of dozens more.

academic.oup.com

A Sun-like star orbiting a black hole

ABSTRACT. We report discovery of a bright, nearby ($G = 13.8;\, \, d = 480\, \rm pc$) Sun-like star orbiting a dark object. We identified the system as a black
academic.oup.com academic.oup.com
Click to expand...

Highly interesting discovery Flyaway, one possibility could be that at one time the sun like star could have been in a double star system where it was orbiting a much larger star that went supernova and the core collapsed at the end of the stars life that then formed the black hole.
 
Spectral analysis of ultra-cool white dwarfs polluted by planetary debris

ABSTRACT
We identify two ultra-cool (⁠Teff<4000
Teff<4000K) metal-polluted (DZ) white dwarfs WD J2147−4035 and WD J1922+0233 as the coolest and second coolest DZ stars known to date with Teff≈3050 Teff≈3050K and Teff≈3340 Teff ≈3340K, respectively. Strong atmospheric collision-induced absorption (CIA) causes the suppression of red optical and infrared flux in WD J1922+0233, resulting in an unusually blue colour given its low temperature. WD J2147−4035 has moderate infrared CIA yet has the reddest optical colours known for a DZ white dwarf. Microphysics improvements to the non-ideal effects and CIA opacities in our model atmosphere code yields reasonable solutions to observations of these ultra-cool stars. WD J2147−4035 has a cooling age of over 10 Gyr which is the largest known for a DZ white dwarf, whereas WD J1922+0233 is slightly younger with a cooling age of 9 Gyr. Galactic kinematics calculations from precise Gaia EDR3 astrometry reveal these ultra-cool DZ stars as likely members of the Galactic disc thus they could be pivotal objects in future studies constraining an upper age limit for the disc of the Milky Way. We present intermediate-resolution spectroscopy for both objects, which provides the first spectroscopic observations of WD J2147−4035. Detections of sodium and potassium are made in both white dwarfs, in addition to calcium in WD J1922+0233 and lithium in WD J2147−4035. We identify the magnetic nature of WD J2147−4035 from Zeeman splitting in the lithium line and also make a tentative detection of carbon, so we classify this star as DZQH. WD J1922+0233 likely accreted planetary crust debris, while the debris composition that polluted WD J2147−4035 remains unconstrained.

academic.oup.com

Spectral analysis of ultra-cool white dwarfs polluted by planetary debris

ABSTRACT. We identify two ultra-cool (${T_\mathrm{eff}}\lt 4000$ K) metal-polluted (DZ) white dwarfs WD J2147−4035 and WD J1922+0233 as the coolest and second c
academic.oup.com academic.oup.com
 
Shock cooling of a red-supergiant supernova at redshift 3 in lensed images

Abstract
The core-collapse supernova of a massive star rapidly brightens when a shock, produced following the collapse of its core, reaches the stellar surface. As the shock-heated star subsequently expands and cools, its early-time light curve should have a simple dependence on the size of the progenitor1 and therefore final evolutionary state. Measurements of the radius of the progenitor from early light curves exist for only a small sample of nearby supernovae2,3,4,5,6,7,8,9,10,11,12,13,14, and almost all lack constraining ultraviolet observations within a day of explosion. The several-day time delays and magnifying ability of galaxy-scale gravitational lenses, however, should provide a powerful tool for measuring the early light curves of distant supernovae, and thereby studying massive stellar populations at high redshift. Here we analyse individual rest-frame exposures in the ultraviolet to the optical taken with the Hubble Space Telescope, which simultaneously capture, in three separate gravitationally lensed images, the early phases of a supernova at redshift z ≈ 3 beginning within 5.8 ± 3.1 hours of explosion. The supernova, seen at a lookback time of approximately 11.5 billion years, is strongly lensed by an early-type galaxy in the Abell 370 cluster. We constrain the pre-explosion radius to be 533+154−119533-119+154 solar radii, consistent with a red supergiant. Highly confined and massive circumstellar material at the same radius can also reproduce the light curve, but because no similar low-redshift examples are known, this is unlikely.

www.nature.com

Shock cooling of a red-supergiant supernova at redshift 3 in lensed images - Nature

The early stages of a lensed supernova at redshift 3 are found in images taken by the Hubble Space Telescope, with observations beginning from around 5.8 hours after the explosion.
www.nature.com www.nature.com
 
Rapid formation of exoplanetesimals revealed by white dwarfs

Abstract
The timing of formation of the first planetesimals determines the mode of planetary accretion and their geophysical and compositional evolution. Astronomical observations of circumstellar disks and Solar System geochronology provide evidence for planetesimal formation during molecular cloud collapse, much earlier than previously estimated. Here we present distinct observational evidence from white dwarf planetary systems for planetesimal formation occurring during the first few hundred thousand years after cloud collapse in exoplanetary systems. A substantial fraction of white dwarfs have accreted planetary material rich in iron core or mantle material. For the exo-asteroids accreted by white dwarfs to form iron cores, substantial heating is required. By simulating planetesimal evolution and collisional evolution, we show that the most likely heat source is short-lived radioactive nuclides such as 26Al (which has a half-life of ~0.7 Myr). Core-rich materials in the atmospheres of white dwarfs, therefore, provide independent evidence for rapid planetesimal formation, concurrent with star formation.

www.nature.com

Rapid formation of exoplanetesimals revealed by white dwarfs - Nature Astronomy

Observational evidence from planetary systems around white dwarfs shows that planetesimal formation occurs during the first few hundred thousand years after cloud collapse. Iron accreted by these white dwarfs must have been formed by short-lived radioactive nuclides driving iron core formation...
www.nature.com www.nature.com
 
Supermassive Black Hole and Broad-line Region in NGC 5548: Results from Five-season Reverberation Mapping

Abstract
NGC 5548 is one of the active galactic nuclei (AGNs) selected for our long-term spectroscopic monitoring with the Lijiang 2.4 m telescope, aiming at investigating the origin and evolution of broad-line regions (BLRs), accurately measuring the mass of supermassive black holes (SMBHs), and understanding the structure and evolution of the AGN. We have performed five-season observations for NGC 5548 with the median sampling interval ranging from 1.25 to 3 days. The light curves of the 5100 Å continuum and broad emission lines are measured after subtracting contamination of the host galaxy starlight. The time lags of the broad He ii, He i, Hγ, and Hβ lines with respect to the 5100 Å continuum are obtained for each season and their mean time lags over the five seasons are 0.69, 4.66, 4.60, and 8.43 days, respectively. The Hγ and Hβ velocity-resolved lag profiles in the seasons of 2015, 2018, 2019, and 2021 are constructed, from which an "M-shaped" structure is found in 2015 but disappears after 2018. Our five-season reverberation mapping (RM) yields an average virial SMBH mass of M•/107 M⊙ = 14.22, with a small standard deviation of 1.89. By combining the previous 18 RM campaigns and our five-season campaign for NGC 5548, we find that there exists a time lag of 3.5 yr between the changes in the BLR size and optical luminosity. In addition, we construct the BLR radius−luminosity relation and the virial relation for NGC 5548.

ShieldSquare Captcha

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Origin of highly r-process-enhanced stars in a cosmological zoom-in simulation of a Milky Way-like galaxy

ABSTRACT
The r-process-enhanced (RPE) stars provide fossil records of the assembly history of the Milky Way (MW) and the nucleosynthesis of the heaviest elements. Observations by the R-Process Alliance (RPA) and others have confirmed that many RPE stars are associated with chemo-dynamically tagged groups, which likely came from accreted dwarf galaxies of the MW. However, we do not know how RPE stars are formed. Here, we present the result of a cosmological zoom-in simulation of an MW-like galaxy with r-process enrichment, performed with the highest resolution in both time and mass. Thanks to this advancement, unlike previous simulations, we find that most highly RPE (r-II; [Eu/Fe] > +0.7) stars are formed in low-mass dwarf galaxies that have been enriched in r-process elements for [Fe/H] <−2.5
⁠, while those with higher metallicity are formed in situ, in locally enhanced gas clumps that were not necessarily members of dwarf galaxies. This result suggests that low-mass accreted dwarf galaxies are the main formation site of r-II stars with [Fe/H] <−2.5
⁠. We also find that most low-metallicity r-II stars exhibit halo-like kinematics. Some r-II stars formed in the same halo show low dispersions in [Fe/H] and somewhat larger dispersions of [Eu/Fe], similar to the observations. The fraction of simulated r-II stars is commensurate with observations from the RPA, and the distribution of the predicted [Eu/Fe] for halo r-II stars matches that observed. These results demonstrate that RPE stars can be valuable probes of the accretion of dwarf galaxies in the early stages of their formation.

 
Flyaway said:
Rapid formation of exoplanetesimals revealed by white dwarfs
Click to expand...
Space.com article on it:
www.space.com

Vaporized asteroids suggest planets and stars form at the same time

Scientists studying "polluted" white dwarf stars find new insights into how planets are made.
www.space.com www.space.com

Flyaway said:
Supermassive Black Hole and Broad-line Region in NGC 5548: Results from Five-season Reverberation Mapping
Click to expand...
www.space.com

Betelgeuse's mysterious 'Great Dimming' may have been triggered by a wandering black hole

"Gravity darkening" might explain the strange episode.
www.space.com www.space.com
 
Imprints of cosmological tensions in reconstructed gravity

Abstract
There has been substantial interest in modifications of the standard Λ cold dark matter (ΛCDM, where Λ is the cosmological constant) cosmological model prompted by tensions between certain datasets, most notably the Hubble tension. The late-time modifications of the ΛCDM model can be parameterized by three time-dependent functions describing the expansion history of the Universe and gravitational effects on light and matter in the large-scale structure. We perform a joint Bayesian reconstruction of these three functions from a combination of recent cosmological observations, utilizing a theory-informed prior built on the general Horndeski class of scalar–tensor theories. This reconstruction is interpreted in light of the well-known Hubble constant, clustering amplitude S8 and lensing amplitude AL tensions. We identify the phenomenological features that alternative theories would need to have to ease some of these tensions, and deduce important constraints on broad classes of modified gravity models. Among other things, our findings suggest that late-time dynamical dark energy and modifications of gravity are not likely to offer a solution to the Hubble tension, or simultaneously solve the AL and S8 tensions.

www.nature.com

Imprints of cosmological tensions in reconstructed gravity - Nature Astronomy

A simultaneous reconstruction of three functions describing the expansion of the Universe and gravitational effects on light and matter shows the extent to which modified gravity can address tensions between the standard cosmological model and a large body of observations.
www.nature.com www.nature.com
 
Just a bit of fun...
www.universal-sci.com

Finding Alien Megastructures Around Nearby Pulsars

For example, in the summer of 2015, a team of astronomers announced that they found what might be an indication of an alien megastructure around Tabby’s Star (KIC 8462852). However, they were quick to point out that any number of possibilities could explain the strange dimming pattern coming from th
www.universal-sci.com www.universal-sci.com
 
A meteorite that crashed on the Gloucestershire town of Winchcombe last year contained water that was a near-perfect match for that on Earth.
Click to expand...

The new analysis also confirms the meteorite's origin.
Camera footage of the fireball has allowed researchers to work out a very precise trajectory.
Calculating backwards, this indicates the meteorite came from the outer asteroid belt between Mars and Jupiter.
Click to expand...

www.bbc.com

Meteorite adds weight to water-from-space theory - BBC News

The space rock that hit a Gloucestershire town last year held water similar to our planet's oceans.
www.bbc.com www.bbc.com
 
One was a great Hannibal Lecter…and the other is an actor….wait…

So if Bennu had zero resistance—then DART’s target—if of similar construction— behaved as a non-Newton at speed? DUNE was right…the slow blade enters.
Just hit off target?
phys.org

Where should we impact an asteroid to effectively deflect its orbit?

Recently, NASA's Double Asteroid Redirection Test (DART) spacecraft crashed into a 170 m asteroid Dimorphos at 6.6 km/s, as the first on-orbit demonstration of deflecting an asteroid by kinetic impact. The DART spacecraft was set to impact the center of Dimorphos nearly head-on. Earth-based...
phys.org

Now you can scroll through the universe

Slashdot

m.slashdot.org m.slashdot.org

As for planet Earth:
phys.org

Worldwide dataset captures Earth in finest ever detail

A global open-source dataset of high-resolution images of Earth—the most extensive and detailed of its kind—has been developed by experts led by UCL with data from the European Space Agency (ESA).
phys.org
 
Last edited:
Helium-enhanced planets along the upper edge of the radius valley

Abstract
The Kepler survey revealed that the radius distribution of sub-Neptunes is bimodal: there is a scarcity of planets between 1.5 and 2.0 R⊕. However, the mechanism that creates the valley is unknown. The low mean densities of sub-Neptunes imply that they formed within a few million years and accreted primordial envelopes. Because these planets receive X-ray and UV fluxes comparable to the gravitational binding energy of their envelopes, their atmospheres are susceptible to mass loss. We model the thermal and compositional evolution of sub-Neptunes undergoing escape with diffusive separation between hydrogen and helium and show that preferential loss of hydrogen can change their atmospheric compositions. Planets with radii between 1.6 and 2.5 R⊕ can obtain atmospheric helium mass fractions in excess of 40% from billions of years of photoevaporation. Such enhancement can be detected through transmission spectroscopy, providing a novel observational test to determine whether atmospheric escape creates the radius valley.

www.nature.com

Helium-enhanced planets along the upper edge of the radius valley - Nature Astronomy

Exoplanets with radii between 1.4 and 2.5 R⊕ may have atmospheres strongly enhanced in helium after a few billion years, due to the preferential loss of hydrogen over helium via photoevaporation. If observed, this phenomenon could demonstrate the importance of photoevaporation in shaping the...
www.nature.com www.nature.com
 
Collimation of the Relativistic Jet in the Quasar 3C 273

Abstract
The collimation of relativistic jets launched from the vicinity of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGNs) is one of the key questions to understand the nature of AGN jets. However, little is known about the detailed jet structure for AGN like quasars since very high angular resolutions are required to resolve these objects. We present very long baseline interferometry (VLBI) observations of the archetypical quasar 3C 273 at 86 GHz, performed with the Global Millimeter VLBI Array, for the first time including the Atacama Large Millimeter/submillimeter Array. Our observations achieve a high angular resolution down to ∼60 μas, resolving the innermost part of the jet ever on scales of ∼105 Schwarzschild radii. Our observations, including close-in-time High Sensitivity Array observations of 3C 273 at 15, 22, and 43 GHz, suggest that the inner jet collimates parabolically, while the outer jet expands conically, similar to jets from other nearby low-luminosity AGNs. We discovered the jet collimation break around 107 Schwarzschild radii, providing the first compelling evidence for structural transition in a quasar jet. The location of the collimation break for 3C 273 is farther downstream from the sphere of gravitational influence (SGI) from the central SMBH. With the results for other AGN jets, our results show that the end of the collimation zone in AGN jets is governed not only by the SGI of the SMBH but also by the more diverse properties of the central nuclei.

ShieldSquare Captcha

iopscience.iop.org iopscience.iop.org
 
It’s not something I imagine that the general public are aware of balloon astronomy probably even amongst those interested in astronomy.

NASA’s Balloon Program Analysis Group recently presented a roadmap to NASA, to guide them on how to plan and fund future balloon astronomy programs. Balloons have been used for over a century to conduct physics experiments, astronomical observations and Earth observing work, but remain relatively unknown to the general public. Balloon astronomy share many advantages with space telescopes, but at a fraction of the cost.
Click to expand...

www.universetoday.com

Many Next-Generation Telescopes are Carried on Balloons. Here's What the Next Decade Holds in Balloon Astronomy

NASA recently published a roadmap for future balloon astronomy missions. Balloons offer many advantages of space telescopes, with less risk.
www.universetoday.com www.universetoday.com

Related report:

A Roadmap For Scientific Ballooning 2020-2030

From 2018 to 2020, the Scientific Balloon Roadmap Program Analysis Group (Balloon Roadmap PAG) served as an community-based, interdisciplinary forum for soliciting and coordinating community analysis and input in support of the NASA Scientific Balloon Program. The Balloon Roadmap PAG was tasked with articulating and prioritizing the key science drivers and needed capabilities of the Balloon Program for the next decade. Additionally, the Balloon Roadmap PAG was asked to evaluate the potential for achieving science goals and maturing technologies of the Science Mission Directorate, evaluate the Balloon Program goals towards community outreach, and asses commercial balloon launch opportunities. The culmination of this work has been a written report submitted to the NASA Astrophysics Division Director.

 
Studies on an interstellar probe - though before you get too excited, it's to explore the interstellar medium (which is interesting anyway - it's what you have to go through to get to). Some good links, especially an ESA roadmap to 2050.


The ESA roadmap:


Related white paper, 'STELLA—Potential European contributions to a NASA-led interstellar probe':

www.frontiersin.org

STELLA—Potential European contributions to a NASA-led interstellar probe

The discovery of a myriad of exoplanets in the past decades has revolutionized the understanding of our place in the Universe. How different are exoplants and do some of them harbor life, just like Earth? To do so, their parent stars must drive a stellar wind and carve what we call astrospheres...
www.frontiersin.org www.frontiersin.org

Previous Centauri Dreams post on the topic, with links:



 
SN 2022ann: A type Icn supernova from a dwarf galaxy that reveals helium in its circumstellar environment

We present optical and near-infrared (NIR) observations of the Type Icn supernova (SN Icn) 2022ann, the fifth member of its newly identified class of SNe. Its early optical spectra are dominated by narrow carbon and oxygen P-Cygni features with absorption velocities of 800 km/s; slower than other SNe Icn and indicative of interaction with a dense, H/He-poor circumstellar medium (CSM) that is outflowing slower than a typical Wolf-Rayet wind velocity of >1000 km/s. We identify helium in NIR spectra obtained two weeks after maximum and in optical spectra at three weeks, demonstrating that the CSM is not fully devoid of helium. We never detect broad spectral features from SN ejecta, including in spectra extending to the nebular phase, a unique characteristic among SNe~Icn. Compared to other SNe Icn, SN 2022ann has a low luminosity, with a peak o-band absolute magnitude of -17.7, and evolves slowly. We model the bolometric light curve and find it is well-described by 1.7 M_Sun of SN ejecta interacting with 0.2 M_sun of CSM. We place an upper limit of 0.04 M_Sun of Ni56 synthesized in the explosion. The host galaxy is a dwarf galaxy with a stellar mass of 10^7.34 M_Sun (implied metallicity of log(Z/Z_Sun) ≈ 0.10) and integrated star-formation rate of log(SFR) = -2.20 M_sun/yr; both lower than 97\% of the galaxies observed to produce core-collapse supernovae, although consistent with star-forming galaxies on the galaxy Main Sequence. The low CSM velocity, nickel and ejecta masses, and likely low-metallicity environment disfavour a single Wolf-Rayet progenitor star. Instead, a binary companion star is likely required to adequately strip the progenitor before explosion and produce a low-velocity outflow. The low CSM velocity may be indicative of the outer Lagrangian points in the stellar binary progenitor, rather than from the escape velocity of a single Wolf-Rayet-like massive star.


phys.org

Study investigates a rare Type Icn supernova

An international team of astronomers has conducted optical and near-infrared observations of a rare Type Icn supernova known as SN 2022ann. The results of the study, published November 9 on the preprint server arXiv, shed more light on the nature of this supernova and its unique properties.
phys.org phys.org
 
An investigation of open clusters Berkeley 68 and Stock 20 using CCD UBV and Gaia DR3 data

We performed detailed photometric and astrometric analyses of the open star clusters Berkeley 68 and Stock 20. This was based on ground-based CCD UBV photometric data complemented by space-based Gaia Data Release 3 photometry and astrometry. 198 stars were identified as likely cluster members for Berkeley 68 and 51 for Stock 20. Two-color diagrams were used to derive the reddening and photometric metallicity for each cluster. The reddening for Berkeley 68 is E(B−V)=0.520±0.032 and 0.400±0.048 mag for Stock 20. Photometric metallicity [Fe/H] is −0.13±0.08 dex for Berkeley 68, and −0.01±0.06 dex for Stock 20. Keeping as constant reddening and metallicity, we determined the distance moduli and ages of the clusters through fitting isochrones to the UBV and Gaia based color-magnitude diagrams. Photometric distances are d=3003±165 pc for Berkeley 69 and 2911±216 pc for Stock 20. The cluster ages are 2.4±0.2 Gyr and 50±10 Myr for Berkeley 68 and Stock 20, respectively. Present-day mass function slopes were found to be Γ=1.38±0.71 and Γ=1.53±0.39 for Berkeley 68 and Stock 20, respectively. These values are compatible with the value of Salpeter (1955). The relaxation times were estimated as 32.55 Myr and 23.17 Myr for Berkeley 68 and Stock 20, respectively. These times are less than the estimated cluster ages, indicating that both clusters are dynamically relaxed. Orbit integration was carried out only for Berkeley 68 since radial velocity data was not available for Stock 20. Analysis indicated that Berkeley 68 was born outside the solar circle and belongs to the thin-disc component of the Milky Way.


phys.org

Astronomers inspect two galactic open clusters

Using the Tubitak National Observatory (TUG) and ESA's Gaia satellite, Turkish astronomers have inspected Berkeley 68 and Stock 20—two galactic open clusters. Results of the study, presented November 17 on the arXiv pre-print server, deliver important insights into the nature and properties of...
phys.org phys.org
 
GD 99: Re-investigation of an old ZZ Ceti companion

Context. Thanks to photometric space missions, we have access to more and more information on the properties of white dwarf stars, especially pulsating ones. In the case of pulsators, we have the opportunity to get an insight into their otherwise hidden interiors by the means of asteroseismology. In addition to space-based observations, we also take advantage of the opportunity to study the pulsations of white dwarf stars from the ground, either as observations that are complementary to space-based measurements or individual observing runs on selected targets across long timescales.
Aims. We aim to investigate long-term, single-site observations of the bright, yet scarcely studied ZZ Ceti star, GD 99. Our main goals are to determine as many eigenmodes for asteroseismology as possible and then to carry out a seismic analysis of this target.
Methods. We performed a Fourier analysis of the light curves obtained in different epochs. After finding the normal modes of the pulsation, we ran the 2018 version of the White Dwarf Evolution Code to build model grids for the period fits. We compared the seismic distance of the best-fit model with the geometric value provided by Gaia measurements.
Results. We find that GD 99 is rich in pulsation modes in the 200-1100 s period range, as we detected seven new periods. Together with the literature data, we were able to use 11 modes for the asteroseismic fits. We accepted an asteroseismic model solution with Teff = 13 500 K and M* = 0.80 Msun as a best fit, however, this suggests a hotter and more massive star than we might have expected based on the spectroscopic values. We also estimated the rotational rate of the star to be 13.17 h, based on TESS observations.


phys.org

Variable star GD 99 investigated by researchers

Using the 1-m Ritchey–Chrétien–Coudé telescope of the Konkoly Observatory in Budapest, Hungary and NASA's Transiting Exoplanet Survey Satellite (TESS), Hungarian astronomers have observed a variable star known as GD 99. Results of the study, published November 21 on the arXiv pre-print server...
phys.org phys.org
 
A team of researchers has discovered at least two new minerals that have never before been seen on Earth in a 15 ton meteorite found two years ago in Somalia—the ninth largest meteorite ever found.
Click to expand...

www.forbes.com

Scientists Discover Two ‘Alien’ Minerals In Meteorite

A team of researchers has discovered at least two new minerals that have never before been seen on Earth in a meteorite.
www.forbes.com www.forbes.com
 
www.bis-space.com

Beyond The Moon Symposium 2022 - The British Interplanetary Society

Wednesday 14 December 2022, 1030- 1700BST Speakers: TBC Sadly due to the current situation in Ukraine this conference has been postponed from 12th April 2022. The new date enables us to coincide with our Apollo 17 celebrations to celebrate the Lunar Module Ascent from the Moon’s surface on 14...
www.bis-space.com www.bis-space.com
 
Forgot to add this:
www.bis-space.com

BEYOND THE MOON SYMPOSIUM - CALL FOR PAPERS - The British Interplanetary Society

Wednesday 14 December 2022 BEYOND THE MOON SYMPOSIUM Celebrating the 50th Anniversary of Apollo 17 – CALL FOR PAPERS – Deadline: TBC As the Lunar Lander ‘Challenger’ left the surface of the Moon 50 years ago to the day, the symposium will celebrate the achievements of Apollo 17 and ask the...
www.bis-space.com www.bis-space.com
 
Grey Havoc said:
www.space.com

Breakthrough wormhole simulation may unite quantum physics and general relativity

The breakthrough could suggest a way to study 'quantum gravity,' the missing link between quantum physics and Einstein's general relativity in the lab.
www.space.com www.space.com
Click to expand...

Quantum Gravity is only one step towards the so called Theory of Everything which unites all of Physics together with M-Theory (what was previously known as String Theory). It is certainly an interesting development, and one that I have been following for years.
 

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