Is the RSGC4 (Alicante 8) cluster a real star cluster?: Peculiar radial velocities of red supergiant stars
Mass-Radius relation for magnetized white dwarfs from SDSS
NASA’s Tiny BurstCube Mission Launches to Study Cosmic Blasts
4 min read
NASA’s Tiny BurstCube Mission Launches to Study Cosmic Blasts BurstCube, shown in this artist’s concept, will orbit Earth as it hunts for short gamma-ray bursts. NASA’s Goddard Space Flight Center Conceptual Image LabNASA’s BurstCube, a shoebox-sized satellite designed to study the universe’s most powerful explosions, is on its way to the International Space Station.
The spacecraft travels aboard SpaceX’s 30th Commercial Resupply Services mission, which lifted off at 4:55 p.m. EDT on Thursday, March 21, from Launch Complex 40 at Cape Canaveral Space Force Station in Florida. After arriving at the station, BurstCube will be unpacked and later released into orbit, where it will detect, locate, and study short gamma-ray bursts – brief flashes of high-energy light.
“BurstCube may be small, but in addition to investigating these extreme events, it’s testing new technology and providing important experience for early career astronomers and aerospace engineers,” said Jeremy Perkins, BurstCube’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The BurstCube satellite sits in its flight configuration in this photo taken in the Goddard CubeSat Lab in 2023. NASA/Sophia RobertsDownload high-resolution images and videos of BurstCube.
Short gamma-ray bursts usually occur after the collisions of neutron stars, the superdense remnants of massive stars that exploded in supernovae. The neutron stars can also emit gravitational waves, ripples in the fabric of space-time, as they spiral together.
Astronomers are interested in studying gamma-ray bursts using both light and gravitational waves because each can teach them about different aspects of the event. This approach is part of a new way of understanding the cosmos called multimessenger astronomy.
The collisions that create short gamma-ray bursts also produce heavy elements like gold and iodine, an essential ingredient for life as we know it.
Currently, the only joint observation of gravitational waves and light from the same event – called GW170817 – was in 2017. It was a watershed moment in multimessenger astronomy, and the scientific community has been hoping and preparing for additional concurrent discoveries since.
“BurstCube’s detectors are angled to allow us to detect and localize events over a wide area of the sky,” said Israel Martinez, research scientist and BurstCube team member at the University of Maryland, College Park and Goddard. “Our current gamma-ray missions can only see about 70% of the sky at any moment because Earth blocks their view. Increasing our coverage with satellites like BurstCube improves the odds we’ll catch more bursts coincident with gravitational wave detections.”
BurstCube’s main instrument detects gamma rays with energies ranging from 50,000 to 1 million electron volts. (For comparison, visible light ranges between 2 and 3 electron volts.)
When a gamma ray enters one of BurstCube’s four detectors, it encounters a cesium iodide layer called a scintillator, which converts it into visible light. The light then enters another layer, an array of 116 silicon photomultipliers, that converts it into a pulse of electrons, which is what BurstCube measures. For each gamma ray, the team sees one pulse in the instrument readout that provides the precise arrival time and energy. The angled detectors inform the team of the general direction of the event.
BurstCube belongs to a class of spacecraft called CubeSats. These small satellites come in a range of standard sizes based on a cube measuring 10 centimeters (3.9 inches) across. CubeSats provide cost-effective access to space to facilitate groundbreaking science, test new technologies, and help educate the next generation of scientists and engineers in mission development, construction, and testing.
Engineers attach BurstCube to the platform of a thermal vacuum chamber at Goddard ahead of testing. NASA/Sophia Roberts“We were able to order many of BurstCube’s parts, like solar panels and other off-the-shelf components, which are becoming standardized for CubeSats,” said Julie Cox, a BurstCube mechanical engineer at Goddard. “That allowed us to focus on the mission’s novel aspects, like the made-in-house components and the instrument, which will demonstrate how a new generation of miniaturized gamma-ray detectors work in space.”
BurstCube is led by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. It’s funded by the Science Mission Directorate’s Astrophysics Division at NASA Headquarters. The BurstCube collaboration includes: the University of Alabama in Huntsville; the University of Maryland, College Park; the University of the Virgin Islands; the Universities Space Research Association in Washington; the Naval Research Laboratory in Washington; and NASA’s Marshall Space Flight Center in Huntsville.
By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
(301) 286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
- Astrophysics
- BurstCube
- CubeSats
- Gamma Rays
- Gamma-Ray Bursts
- Gravitational Waves
- International Space Station (ISS)
- Neutron Stars
- Sensing the Universe & Multimessenger Astronomy
- The Universe
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Wed 27 Mar 10:00: pop-cosmos: Comprehensive Forward Modelling of Photometric Galaxy Survey Data
Projects such as the imminent Vera C. Rubin Observatory are critical tools for understanding cosmological questions like the nature of dark energy. By observing huge numbers of galaxies, they enable us to map the large scale structure of the Universe. To do this, however, we need reliable ways of estimating galaxy redshifts from only photometry. I will present an overview of our pop-cosmos forward modelling framework for photometric galaxy survey data, a novel approach which connects photometric redshift inference to a physical picture of galaxy evolution. Within pop-cosmos, we model galaxies as draws from a population prior distribution over redshift, mass, dust properties, metallicity, and star formation history. These properties are mapped to photometry using an emulator for stellar population synthesis (speculator/photulator), followed by the application of a learned model for a survey’s noise properties. Application of selection cuts enables the generation of mock galaxy catalogues. This naturally enables us to use simulation-based inference to solve the inverse problem of calibrating the population-level prior on physical parameters from a deep photometric galaxy survey. The resulting model can then be used to derive accurate redshift distributions for upcoming photometric surveys, for instance for facilitating weak lensing and clustering science. We use a diffusion model as a flexible population-level prior, and optimise its parameters by minimising the Wasserstein distance between forward-simulated photometry and the real survey data. I will show applications of this framework to COSMOS data, and will demonstrate how we are able to extract the redshift distribution, and make inference about galaxy physics, from our learned population prior.
- Speaker: Stephen Thorp - Oskar Klein Centre, Stockholm University
- Wednesday 27 March 2024, 10:00-11:00
- Venue: Martin Ryle Seminar Room, KICC.
- Series: Astro Data Science Discussion Group; organiser: Sinan Deger.
Mon 22 Apr 13:00: Title to be confirmed
Abstract not available
- Speaker: Licia Verde (University of Barcelona)
- Monday 22 April 2024, 13:00-14:00
- Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
- Series: Cosmology Lunch; organiser: Fiona McCarthy.
Mon 25 Mar 13:00: The FLAMINGO project: revisiting the S8 tension and the role of baryonic physics
A number of recent studies have found evidence for a tension between observations of large-scale structure (LSS) and the predictions of the standard model of cosmology with the cosmological parameters fit to the cosmic microwave background (CMB). The origin of this ‘S8 tension’ remains unclear, but possibilities include new physics beyond the standard model, unaccounted for systematic errors in the observational measurements and/or uncertainties in the role that baryons play. In this talk, I will examine the latter possibility using the new FLAMINGO suite of large-volume cosmological hydrodynamical simulations. I will discuss how important ‘feedback’ processes that affect the baryons are implemented and calibrated in the simulations and how the simulations are projected onto observable space for comparisons with observational measurements of cosmic shear, CMB lensing, and the thermal Sunyaev-Zel’dovich (tSZ) effect. I will then focus on the dependence of the predictions on the efficiency and nature of baryonic feedback and whether or not it can plausibly resolve the S8 tension. Finally, I will discuss some independent tests that the simulations can be subjected to in order to build confidence (or undermine it!) in our cosmological conclusions.
- Speaker: Ian McCarthy (Liverpool John Moores University)
- Monday 25 March 2024, 13:00-14:00
- Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
- Series: Cosmology Lunch; organiser: Fiona McCarthy.
Combining Gaia and GRAVITY: Characterising Five New Directly Detected Substellar Companions
At least one in a dozen stars shows evidence of planetary ingestion
Nature, Published online: 20 March 2024; doi:10.1038/s41586-024-07091-y
By analysing the chemical abundance differences of pairs of co-moving stars born together, it is found that about 8% show chemical signatures that indicate ingestion of planetary material.Planet-eating stars hint at hidden chaos in the Milky Way
Nature, Published online: 20 March 2024; doi:10.1038/d41586-024-00847-6
A handful of middle-aged stars seem to have gobbled up a planet, challenging assumptions about the stability of such systems.Billions of stars have swallowed up a planet
Documentation Software Engineer (Fixed Term)
Fixed-term: The funds for this post are available until 31 March 2026 in the first instance.
This is an exciting opportunity for Software Developer to join the Institute of Astronomy (IoA), University of Cambridge, as part of the data processing group for the European Space Agency's Gaia project (https://www.cosmos.esa.int/web/gaia), within the IoA Data Projects (CamCEAD) group. Gaia is a space observatory of the European Space Agency (ESA), launched in 2013, operational until 2025 and a final data release 2030/31. The core goal of the Gaia project is to produce the largest, most precise three-dimensional map of our galaxy by surveying over one billion stars and analysing their position, motion, and spectra, to reveal the Milky Way present-day structure and uncover its formation and evolution.
The successful candidate will work with the Gaia software development team and their main commitment will be the preparation of the documentation for the Gaia Data Releases (GDRs), with GDR4 foreseen not before end of 2025 and the final GDR5 by 2030/31. They will also be responsible for the enhancement and maintenance of the Gaia in the UK (https://www.gaia.ac.uk) webpage.
The successful candidate will hold a qualification (Master or equivalent) in a relevant discipline (e.g. computer science, mathematics, astronomy, physics or engineering). The Gaia consortium adopted LaTeX to write the documentation, hence its knowledge is essential. The documentation is also published as webpage, which makes the conversion from LaTeX to HTML one of the key responsibilities of the documentation team. In this context also the knowledge of XML and the understanding of web application, including accessibility, usability and security, are necessary. This skill will also be applicable for the Gaia in the UK webpage.
The Gaia documentation reflects the complexity of the project and many members of the consortium contribute to it, therefore the ability to handle complex documents is mandatory, as also the ability to proofread scientific or technical publications. Good team working and interpersonal skills will be required to communicate with the consortium development partners in other European institutes and ESA. Familiarity with astronomy and/or Gaia are desirable but not essential.
The role will grant opportunities to interact with the wider CamCEAD team, with the potential to contribute to other projects, including ground based astronomical surveys, medical imaging, and with the whole IoA community as well.
The ability to work as part of a team and have good communication skills is also required. The post-holder will be required to attend meetings both elsewhere in the UK and overseas.
Click the 'Apply' button below to register an account with our recruitment system (if you have not already) and apply online.
Closing Date: 23:59 GMT on Sunday, 21 April 2024
Applications will be reviewed after the closing date and short-listed candidates will be interviewed Friday, 3rd May 2024. Interviews will be held on-line.
Please indicate the contact details of three academic referees on the online application form and upload a full curriculum vitae (CV), list of publications, and a research/technical experience statement (with the research/technical experience statement totaling three pages max, in 11pt. font).
Note that references will only be requested for shortlisted candidates. The names and email contact details of three referees are a necessary part of the submission. If short-listed for interview, you should advise your nominated referees that their references will be requested with a deadline of Thursday, 2nd May 2024.
Please quote reference LG40991 on your application and in any correspondence about this vacancy.
The University actively supports equality, diversity and inclusion and encourages applications from all sections of society. The University of Cambridge thrives on the diversity of its staff and students. Applications from underrepresented groups are particularly welcome. We have an active Equality and Diversity Committee which continually works to further the aims of the Athena SWAN charter. The University has a number of family-friendly policies and initiatives, including a returning-carer scheme, childcare costs support, university workplace nurseries, university holiday play-schemes, and a shared parental-leave policy. As part of its commitment to providing a family-friendly environment for researchers, the IoA ensures that should parental leave be needed during the course of employment, there is provision for extension to contract to compensate for the parental leave taken.
The University has a responsibility to ensure that all employees are eligible to live and work in the UK.
The transient event in NGC 1566 from 2017 to 2019 I. An eccentric accretion disk and a turbulent, disk-dominated broad-line region unveiled by double-peaked Ca II and O I lines
High-precision astrometry with VVV -- II. A near-infrared extension of Gaia into the Galactic plane
NASA Radar Finds Ice Deposits at Moon’s North Pole
4 min read
NASA Radar Finds Ice Deposits at Moon’s North Pole Additional evidence of water activity on moonUsing data from a NASA radar that flew aboard India’s Chandrayaan-1 spacecraft, scientists have detected ice deposits near the moon’s north pole. NASA’s Mini-SAR instrument, a lightweight, synthetic aperture radar, found more than 40 small craters with water ice. The craters range in size from 1 to 9 miles (2 to15 km) in diameter. Although the total amount of ice depends on its thickness in each crater, it’s estimated there could be at least 1.3 trillion pounds (600 million metric tons) of water ice.
Mini-SAR map of the Circular Polarization Ratio (CPR) of the north pole of the Moon. Fresh, “normal” craters (red circles) show high values of CPR inside and outside their rims. This is consistent with the distribution of rocks and ejected blocks around fresh impact features, indicating that the high CPR here is surface scattering. The “anomalous” craters (green circles) have high CPR within, but not outside their rims. Their interiors are also in permanent sun shadow. These relations are consistent with the high CPR in this case being caused by water ice, which is only stable in the polar dark cold traps. We estimate over 600 million cubic meters (1 cubic meter = 1 metric ton) of water in these features.The Mini-SAR has imaged many of the permanently shadowed regions that exist at both poles of the Moons. These dark areas are extremely cold and it has been hypothesized that volatile material, including water ice, could be present in quantity here. The main science object of the Mini-SAR experiment is to map and characterize any deposits that exist.
Mini-SAR is a lightweight (less than 10 kg) imaging radar. It uses the polarization properties of reflected radio waves to characterize surface properties. Mini-SAR sends pulses of radar that are left-circular polarized. Typical planetary surfaces reverse the polarization during the reflection of radio waves, so that normal echoes from Mini-SAR are right circular polarized. The ratio of received power in the same sense transmitted (left circular) to the opposite sense (right circular) is called the circular polarization ratio (CPR). Most of the Moon has low CPR, meaning that the reversal of polarization is the norm, but some targets have high CPR. These include very rough, fresh surfaces (such as a young, fresh crater) and ice, which is transparent to radio energy and multiply scatters the pulses, leading to an enhancement in same sense reflections and hence, high CPR. CPR is not uniquely diagnostic of either roughness or ice; the science team must take into account the environment of the occurrences of high CPR signal to interpret its cause.
The fresh impact crater Main L (14 km diameter, 81.4° N, 22° E ), which shows high CPR inside and outside its rim. SC is the “same sense, circular” polarization; CPR is “circular polarization ratio.” The histograms at right show that the high CPR values within (red line) and outside the crater rim (green line) are nearly identical.Numerous craters near the poles of the Moon have interiors that are in permanent sun shadow. These areas are very cold and water ice is stable there essentially indefinitely. Fresh craters show high degrees of surface roughness (high CPR) both inside and outside the crater rim, caused by sharp rocks and block fields that are distributed over the entire crater area. However, Mini-SAR has found craters near the north pole that have high CPR inside, but not outside their rims. This relation suggests that the high CPR is not caused by roughness, but by some material that is restricted within the interiors of these craters. We interpret this relation as consistent with water ice present in these craters. The ice must be relatively pure and at least a couple of meters thick to give this signature.
An “anomalous” crater on the floor of Rozhdestvensky (9 km Diameter, 84.3° N, 157° W), near the north pole of the Moon. This feature shows high CPR within the crater rim, but low CPR outside, suggesting that roughness (which occurs throughout a fresh crater) is not the cause of the elevated CPR. This feature’s interior is in permanent sun shadow. SC stands for “same sense, circular”, OC stands for “opposite sense, circular” and CPR is the “circular polarization ratio.” The histogram of CPR values clearly shows that interior points (red line) have higher CPR values than those outside the crater rim (green line).The estimated amount of water ice potentially present is comparable to the quantity estimated solely from the previous mission of Lunar Prospector’s neutron data (several hundred million metric tons.) The variation in the estimates between Mini-SAR and the Lunar Prospector’s neutron spectrometer is due to the fact that it only measures to depths of about one-half meter, so it would underestimate the total quantity of water ice present. At least some of the polar ice is mixed with lunar soil and thus, invisible to our radar.
“The emerging picture from the multiple measurements and resulting data of the instruments on lunar missions indicates that water creation, migration, deposition and retention are occurring on the moon,” said Paul Spudis, principal investigator of the Mini-SAR experiment at the Lunar and Planetary Institute in Houston. “The new discoveries show the moon is an even more interesting and attractive scientific, exploration and operational destination than people had previously thought.”
“After analyzing the data, our science team determined a strong indication of water ice, a finding which will give future missions a new target to further explore and exploit,” said Jason Crusan, program executive for the Mini-RF Program for NASA’s Space Operations Mission Directorate in Washington.
The Mini-SAR’s findings are being published in the journal Geophysical Research Letters. The results are consistent with recent findings of other NASA instruments and add to the growing scientific understanding of the multiple forms of water found on the moon. The agency’s Moon Mineralogy Mapper discovered water molecules in the moon’s polar regions, while water vapor was detected by NASA’s Lunar Crater Observation and Sensing Satellite, or LCROSS.
Mini-SAR and Moon Mineralogy Mapper are two of 11 instruments on the Indian Space Research Organization’s Chandrayaan-1. The Applied Physics Laboratory in Laurel, Md., performed the final integration and testing on Mini-SAR. It was developed and built by the Naval Air Warfare Center in China Lake, Calif., and several other commercial and government contributors.
Get more information about Chandrayaan-1
March 2, 2010
Fri 03 May 11:30: Modelling supermassive black holes: accretion, spin evolution, jets and winds
Abstract not available
- Speaker: Martin Bourne (IoA)
- Friday 03 May 2024, 11:30-12:30
- Venue: Ryle seminar room + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Wed 15 May 14:00: Title to be confirmed
Abstract not available
- Speaker: Michael Cates, University of Cambridge
- Wednesday 15 May 2024, 14:00-15:00
- Venue: MR2.
- Series: Theoretical Physics Colloquium; organiser: Ronak M Soni.
Wed 08 May 14:00: Title to be confirmed
Abstract not available
- Speaker: Vyacheslav Rychkov, Institut des Hautes Études Scientifiques
- Wednesday 08 May 2024, 14:00-15:00
- Venue: MR2.
- Series: Theoretical Physics Colloquium; organiser: Ronak M Soni.