Astronomy and Planetary Science Thread

Discovery of a resolved white dwarf-brown dwarf binary with a small projected separation: SDSS J222551.65+001637.7AB

We present the confirmation of SDSS J222551.65+001637.7AB as a closely separated, resolved, white dwarf-brown dwarf binary. We have obtained spectroscopy from GNIRS and seeing-limited Ks-band imaging from NIRI on Gemini North. The target is spatially resolved into its constituent components: a 10926± 246 K white dwarf, with log g=8.214±0.168 and a mass of 0.66+0.11−0.06 M⊙, and an L4 brown dwarf companion, which are separated by 0.9498±0.0022". We derive the fundamental properties of the companion from the Sonora-Bobcat evolutionary models, finding a mass of 25−53 MJup and a radius of 0.101−0.128 R⊙ for the brown dwarf, at a confidence level of 1σ. We use wdwarfdate to determine the age of the binary as 1.97+4.41−0.76 Gyr. A kinematic analysis shows that this binary is likely a member of the thick disc. The distance to the binary is 218+14−13 pc, and hence the projected separation of the binary is 207+13−12 AU. Whilst the white dwarf progenitor was on the main sequence the binary separation would have been 69±5 AU. SDSS J222551.65+001637.7AB is the third closest spatially resolved white dwarf-brown dwarf binary after GD 165AB and PHL 5038AB.


phys.org

SDSS J222551.65+001637.7AB is a white dwarf–brown dwarf binary system, observations find

Using the Gemini North telescope, astronomers have performed spectroscopic observations of a binary system known as SDSS J222551.65+001637.7AB. Results of the observational campaign indicate that the system consists of a white dwarf and a brown dwarf companion. The finding was reported December...
phys.org phys.org
 
MeerKAT discovery of 13 new pulsars in Omega Centauri

The most massive globular cluster in our Galaxy, Omega Centauri, is an interesting target for pulsar searches, because of its multiple stellar populations and the intriguing possibility that it was once the nucleus of a galaxy that was absorbed into the Milky Way. The recent discoveries of pulsars in this globular cluster and their association with known X-ray sources was a hint that, given the large number of known X-ray sources, there is a much larger undiscovered pulsar population. We used the superior sensitivity of the MeerKAT radio telescope to search for pulsars in Omega Centauri. In this paper, we present some of the first results of this survey, including the discovery of 13 new pulsars; the total number of known pulsars in this cluster currently stands at 18. At least half of them are in binary systems and preliminary orbital constraints suggest that most of the binaries have light companions. We also discuss the ratio between isolated and binaries pulsars and how they were formed in this cluster.


phys.org

Thirteen new pulsars discovered with MeerKAT

Using the MeerKAT radio telescope, astronomers from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany and elsewhere, have detected 13 new pulsars in the globular cluster Omega Centauri. The finding was detailed in a paper published in the Monthly Notices of the Royal...
phys.org phys.org
 
Comprehensive spectroscopic and photometric study of pulsating eclipsing binary star AI Hya

The pulsating eclipsing binaries are remarkable systems that provide an opportunity to probe the stellar interior and to determine the fundamental stellar parameters precisely. Especially the detached eclipsing binary systems with (a) pulsating component(s) are significant objects to understand the nature of the oscillations since the binary effects in these systems are negligible. Recent studies based on space data have shown that the pulsation mechanisms of some oscillating stars are not completely understood. Hence, comprehensive studies of a number of pulsating stars within detached eclipsing binaries are important. In this study, we present a detailed analysis of the pulsating detached eclipsing binary system AI Hya which was studied by two independent groups with different methods. We carried out a spectroscopic survey to estimate the orbital parameters via radial velocity measurements and the atmospheric parameters of each binary component using the composite and/or disentangled spectra. We found that the more luminous component of the system is a massive, cool and chemically normal star while the hotter binary component is a slightly metal-rich object. The fundamental parameters of AI Hya were determined by the analysis of binary variations and subsequently used in the evolutionary modelling. Consequently, we obtained the age of the system as 850 ± 20 Myr and found that both binary components are situated in the Delta Scuti instability strip. The frequency analysis revealed pulsation frequencies between the 5.5 - 13.0 d−1 and we tried to estimate which binary component is the pulsating one. However, it turned out that those frequencies could originate from both binary components.

 
SDSS J134441.83+204408.3: A highly asynchronous, short-period magnetic cataclysmic variable with a 56 MG field strength

When the accreting white dwarf in a magnetic cataclysmic variable star (mCV) has a field strength in excess of 10 MG, it is expected to synchronize its rotational frequency to the binary orbit frequency, particularly at small binary separations, due to the steep radial dependence of the magnetic field. We report the discovery of an mCV (SDSS J134441.83+204408.3; hereafter, J1344) that defies this expectation by displaying asynchronous rotation (Pspin/Porb=0.893) in spite of a high surface field strength (B=56 MG) and a short orbital period (114 min). Previously misidentified as a synchronously rotating mCV, J1344 was observed by TESS during sector 50, and the resulting power spectrum shows distinct spin and orbital frequencies, along with various sidebands and harmonics. Although there are several other asynchronous mCVs at short orbital periods, the presence of cyclotron humps in J1344's SDSS spectrum makes it possible to directly measure the field strength in the cyclotron-emitting region; a previously study estimated 65 MG based on its identification of two cyclotron humps, but we revise this to 56±2 MG based on the detection of a third hump and on our modeling of the cyclotron spectrum. Short-period mCVs with field strengths above 10 MG are normally expected to be synchronous, so the highly asynchronous rotation in J1344 presents an interesting challenge for theoretical studies of spin-period evolution.


phys.org

Astronomers discover a peculiar cataclysmic variable star

Using NASA's Transiting Exoplanet Survey Satellite (TESS), astronomers have discovered a peculiar cataclysmic variable star. The newly found system, designated SDSS J134441.83+204408.3 (or J1344 for short) is a highly asynchronous, short-period magnetic cataclysmic variable, despite its high...
phys.org phys.org
 
Grey Havoc said:
www.bbc.com

Asteroid 2023 BU: Space rock passes closer than some satellites

About the size of a bus, the space rock whipped over the southern tip of South America.
www.bbc.com www.bbc.com
Click to expand...
That brings to mind a post seen a little bit ago in a space group over on MeWe,
referenced article is, https://www.standard.co.uk/tech/sci...h-closest-approaches-nasa-space-b1055709.html

And within it is: "An airplane-sized asteroid named 2020 BZ14 will also pass at around 2,100,000 miles away." Okay, so, does 'airplane-sized' mean Bede BD-5 sized or Airbus A380 sized?
 
Usually when I have seen that comparison in the past in this context, it was Jumbo jets they were thinking of.
 
Grey Havoc said:
www.space.com

How to see the green comet C/2022 E3 (ZTF) visible in the night sky now as it approaches Earth

Don't miss your chance to see this visitor from the outer reaches of our solar system as it prepares to make its closest approach to Earth.
www.space.com www.space.com

www.dublinlive.ie

Rare green comet not seen since Stone Age to be visible in Irish skies

The comet, also known as ZTF, will be visible from Earth for the first time in 50,000 years making it a once-in-a-lifetime event
www.dublinlive.ie www.dublinlive.ie
Click to expand...
Be somewhere without cloud cover.

This has been the issue for me.
 
southwestforests said:
Grey Havoc said:
www.bbc.com

Asteroid 2023 BU: Space rock passes closer than some satellites

About the size of a bus, the space rock whipped over the southern tip of South America.
www.bbc.com www.bbc.com
Click to expand...
That brings to mind a post seen a little bit ago in a space group over on MeWe,
referenced article is, https://www.standard.co.uk/tech/sci...h-closest-approaches-nasa-space-b1055709.html

And within it is: "An airplane-sized asteroid named 2020 BZ14 will also pass at around 2,100,000 miles away." Okay, so, does 'airplane-sized' mean Bede BD-5 sized or Airbus A380 sized?
Click to expand...
In Israel there is a different standard for measuring asteroids:

https://www.jpost.com/science/article-729244

2 asteroids the size of 100 pugs to pass Earth Tuesday - NASA​

Both asteroids 2019 BO2 and 2019 BZ4 are around 36 meters in diameter, meaning 100 pugs. But it won't hit us – pugs are more likely to.​

By AARON REICH
Published: JANUARY 22, 2023 16:56
Click to expand...
 
Not sure if already posted, but thought I'd post it again anyway even if because just look at it.
www.nasa.gov

How to Shape a Spiral Galaxy

New observations from SOFIA are shedding light on how spiral-shaped galaxies, like our own Milky Way, get their iconic shape.
www.nasa.gov www.nasa.gov

Fn-v81dWIAEZSi1
 
Interesting... J1407b, aka Mamajek's object, was supposed to be the exoplanet with the largest ring system ever found - something like 2/3 of an AU across, with gaps indicating the presence of moons with up to 0.8 earth mass.

However, it is well overdue for another transit of the star even if it is on the longest-period orbit predicted. I appears instead that it's a free brown dwarf or similar with a young planetary system that just happened to pass in front of J1407 when we were looking at it.

View: https://www.youtube.com/watch?v=DCUAaJfgEJY&t=631s
 
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If the Andromeda galaxy were brighter, it would look like this in our sky. Andromeda is about six times wider than the Moon... but it's 61.6 *trillion* times farther away.

Fok5rAIXsAEdhgg
 
jeffb said:
If the Andromeda galaxy were brighter, it would look like this in our sky. Andromeda is about six times wider than the Moon... but it's 61.6 *trillion* times farther away.

Fok5rAIXsAEdhgg
Click to expand...

And of course in about 2.5 Billion years (give or take) the Andromeda galaxy (M-31) will merge into our own Galaxy creating a giant Elliptical galaxy.
 
DESI z >~ 5 Quasar Survey. I. A First Sample of 400 New Quasars at z ~ 4.7-6.6

We report the first results of a high-redshift (z >~ 5) quasar survey using the Dark Energy Spectroscopic Instrument (DESI). As a DESI secondary target program, this survey is designed to carry out a systematic search and investigation of quasars at z >~ 5, up to redshift 6.8. The target selection is based on the DESI Legacy Imaging Surveys (the Legacy Surveys) DR9 photometry, combined with the Pan-STARRS1 data and J-band photometry from public surveys. A first quasar sample has been constructed from the DESI Survey Validation 3 (SV3) and first-year observations until May 2022. This sample includes more than 400 new quasars at redshift 4.7 <= z < 6.6, down to 21.5 magnitude in the z band, discovered from 35% of the entire target sample. Remarkably, there are 220 new quasars identified at z >= 5, more than one third of existing quasars previously published at this redshift. The observations so far result in an average success rate of 23% at z > 4.7. The current spectral dataset has already allowed analysis of interesting individual objects (e.g., quasars with damped Lyα absorbers and broad absorption line features), and statistical analysis will follow the survey's completion. A set of science projects will be carried out leveraging this program, including quasar luminosity function, quasar clustering, intergalactic medium, quasar spectral properties, intervening absorbers, and properties of early supermassive black holes. Additionally, a sample of 38 new quasars at z ~ 3.8-5.7 discovered from a pilot survey in the DESI SV1 is also published in this paper.


phys.org

Hundreds of new high-redshift quasars discovered

An international team of astronomers reports the detection of more than 400 new high-redshift quasars using the Dark Energy Spectroscopic Instrument (DESI). The discovery, published February 3 on the arXiv preprint server, greatly improves the number of known distant quasars and demonstrates the...
phys.org phys.org
 
Discovery of the Tadpole Molecular Cloud near the Galactic Nucleus

Abstract
In this paper, we report the discovery of an isolated, peculiar compact cloud with a steep velocity gradient at 2.′6 northwest of Sgr A*. This “Tadpole” molecular cloud is unique owing to its characteristic head-tail structure in the position–velocity space. By tracing the CO J = 3–2 intensity peak in each velocity channel, we noticed that the kinematics of the Tadpole can be well reproduced by a Keplerian motion around a point-like object with a mass of 1 × 105 M⊙. Changes in line intensity ratios along the orbit are consistent with the Keplerian orbit model. The spatial compactness of the Tadpole and absence of bright counterparts in other wavelengths indicate that the object could be an intermediate-mass black hole.


phys.org

'Tadpole' molecular cloud appears to be playing around black hole

A peculiar cloud of gas, nicknamed the Tadpole due to its shape, appears to be revolving around a space devoid of any bright objects. This suggests that the Tadpole is orbiting a dark object, most likely a black hole 100,000 times more massive than the sun. Future observations will help...
phys.org phys.org
 
NASA's planetary radar captures detailed view of oblong asteroid

On Feb. 3, an asteroid more than three times as long as it is wide safely flew past Earth at a distance of about 1.1 million miles (1.8 million kilometers, or a little under five times the distance between the Moon and Earth). While there was no risk of the asteroid—called 2011 AG5—impacting our planet, scientists at NASA's Jet Propulsion Laboratory in Southern California closely tracked the object, making invaluable observations to help determine its size, rotation, surface details, and, most notably, shape.
Click to expand...

phys.org

NASA's planetary radar captures detailed view of oblong asteroid

On Feb. 3, an asteroid more than three times as long as it is wide safely flew past Earth at a distance of about 1.1 million miles (1.8 million kilometers, or a little under five times the distance between the Moon and Earth). While there was no risk of the asteroid—called 2011 AG5—impacting our...
phys.org phys.org
 
A CCD Search for Variable Stars in the Open Cluster NGC 6611

We present the results of the UBVIC variability survey in the young open cluster NGC 6611 based on observations obtained during 34 nights spanning one year. In total, we found 95 variable stars. Most of these stars are classified as periodic and irregular pre-main sequence (PMS) stars. The analysis of the JHKS 2MASS photometry and four-colour IRAC photometry revealed 165 Class II young stellar sources, 20 of which are irregular variables and one is an eclipsing binary. These classifications, complemented by JHK UKIDSS photometry and riHα VPHAS photometry, were used to identify 24 candidates for classical T Tauri stars and 30 weak-lined T Tauri stars. In addition to the PMS variables, we discovered eight δ Scuti candidates. None of these were previously known. Furthermore, we detected 17 eclipsing binaries where two were previously known. Based on the proper motions provided by the Gaia EDR3 catalogue, we calculated the cluster membership probabilities for 91 variable stars. For 61 variables, a probability higher than 80% was determined, which makes them cluster members. Only 25 variables with a probability less than 20% were regarded to be non-members.


phys.org

Dozens of variable stars detected in the open cluster NGC 6611

Using three ground-based telescopes in Chile, astronomers have conducted a search for variable stars in the open cluster NGC 6611. In result, they detected 95 variables and the majority of them are most likely cluster members. The discovery was published February 1 in the Monthly Notices of the...
phys.org phys.org
 
The Thousand-Pulsar-Array program on MeerKAT -- IX. The time-averaged properties of the observed pulsar population

We present the largest single survey to date of average profiles of radio pulsars, observed and processed using the same telescope and data reduction software. Specifically, we present measurements for 1170 pulsars, observed by the Thousand Pulsar Array (TPA) programme at the 64-dish SARAO MeerKAT radio telescope, in a frequency band from 856 to 1712 MHz. We provide rotation measures (RM), dispersion measures, flux densities and polarization properties. The catalogue includes 254 new RMs that substantially increase the total number of known pulsar RMs. Our integration times typically span over 1000 individual rotations per source. We show that the radio (pseudo)luminosity has a strong, shallow dependence on the spin-down energy, proportional to E˙0.15±0.04, that contradicts some previous proposals of population synthesis studies. In addition, we find a significant correlation between the steepness of the observed flux density spectra and E˙, and correlations of the fractional linear polarization with E˙, the spectral index, and the pulse width, which we discuss in the context of what is known about pulsar radio emission and how pulsars evolve with time. On the whole, we do not see significant correlations with the estimated surface magnetic field strength, and the correlations with E˙ are much stronger than those with the characteristic age. This finding lends support to the suggestion that magnetic dipole braking may not be the dominant factor for the evolution of pulsar rotation over the lifetimes of pulsars. A public data release of the high-fidelity time-averaged pulse profiles in full polarization accompanies our catalogue.


phys.org

Astronomers measure the heartbeat of spinning stars

An international team of scientist have used the MeerKAT radio telescope to observe the pulsing heartbeat of the universe as neutron stars are born and form swirling lightning storms which last for millions of years.
phys.org phys.org
 
Origin of multiwavelength emission from flaring high redshift blazar PKS 0537-286

The high redhsift blazars powered by supermassive black holes with masses exceeding 109M have the highest jet power and luminosity and are important probes to test the physics of relativistic jets at the early epochs of the Universe. We present a multi-frequency spectral and temporal study of high redshift blazar PKS 0537-286 by analyzing data from Fermi-LAT, NuSTAR Swift XRT and UVOT. Although the time averaged γ-ray spectrum of the source is relatively soft (indicating the high-energy emission peak is below the GeV range), several prominent flares were observed when the spectrum hardened and the luminosity increased above 1049ergs−1. The X-ray emission of the source varies in different observations and is characterised by a hard spectrum ≤1.38 with a luminosity of >1047ergs−1. The broadband spectral energy distribution in the quiescent and flaring periods was modeled within a one-zone leptonic scenario assuming different locations of the emission region and considering both internal (synchrotron radiation) and external (from the disk, broad-line region and dusty torus) photon fields for the inverse Compton scattering. The modeling shows that the most optimistic scenario, from the energy requirement point of view, is when the jet energy dissipation occurs within the broad-line region. The comparison of the model parameters obtained for the quiescent and flaring periods suggests that the flaring activities are most likely caused by the hardening of the emitting electron spectral index and shifting of the cut-off energy to higher values.


phys.org

Astronomers investigate multiwavelength emission from the blazar PKS 0537-286

Using three space telescopes, Armenian astronomers have observed a flaring high-redshift blazar known as PKS 0537-286. Results of the observational campaign, presented February 15 on the pre-print server arXiv, deliver important insights into the properties and origin of the multiwavelength...
phys.org phys.org
 
Confirmation of two magnetic cataclysmic variables as polars: 1RXS J174320.1-042953 and YY Sex

We present our analysis of new and archived observations of two candidate magnetic cataclysmic variables, namely 1RXS J174320.1-042953 and YY Sex. 1RXS J174320.1-042953 was observed in two distinctive high and low states where a phase shift was seen, which could be due to the changes in the shape, size, and (or) location of the accretion region. We find that its orbital X-ray modulations only persist in the soft (0.3-2.0 keV) energy band, which could be attributed to the photoelectric absorption in the accretion flow. The X-ray spectra exhibit a multi-temperature post-shock region where the hard X-rays are absorbed through a thick absorber with an equivalent hydrogen column of ∼7.5 × 1023 cm−2, which partially covers ∼56 per cent of the emission. No soft X-ray excess was found to be present; however, a soft X-ray emission with a blackbody temperature of ∼97 eV describes the spectra. Extensive TESS observations of YY Sex allow us to refine its orbital period to 1.5746 ± 0.0011 h. We did not find any signature of previously reported spin or beat periods in this system. Furthermore, our new polarimetric observations show clear circular polarization modulated on the orbital period only. Finally, both systems show strong Balmer and He II 4686 A∘ emission lines in the optical spectra, further indicative of their magnetic nature.


phys.org

Astronomers detect two new polars

Using multiple telescopes, astronomers have detected two new magnetic cataclysmic variable systems of the polar subclass and determined their fundamental properties. The finding, which could help us better understand the nature of polars in general, was published February 20 on the arXiv...
phys.org phys.org
 
Surprising newfound ocean bacteria could aid search for alien life

Such hot springs likely also exist on oceanic worlds like Jupiter's moon Europa and the Saturn satellite Enceladus, so these observations sharpen our understanding of the forms alien life might take on those moons, astronomers say.

The newfound bacteria, Sulfurimonas pluma, belongs to a family of organisms that to date had only been known from volcanic vents on Earth's seafloors, as it cannot tolerate high oxygen levels in water elsewhere. So scientists were surprised to find a new member, smaller than its relatives, burgeoning in oxygen-rich water plumes hundreds of meters away from them.
Click to expand...

www.space.com

Surprising newfound ocean bacteria could aid search for alien life

'This was never observed before in this type of environment.'
www.space.com www.space.com
 
I would really like to see some form of submersible to Europa to explore the ocean that is under all that ice to confirm whether or not there is some sort of alien life there, and this latest discovery involving bacteria could aid such a mission.
 

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