Podcasts about Hipparcos

Thanks for joining me again on Astronomy Daily. Andrew Dunkley here, your host. Hope you had a great weekend. Coming up on today's program to kick off the week, more on the Hipparcos star chart.We've talked about this before and it's fascinating. We've got more information on that.A SpaceX moon mission is a distinct possibility; where stars go to die and something really amazing at Epcot which was unfortunately not there when I last went but I might have to go back again. That's all coming up on this edition of Astronomy Daily.S01E72Today's Space, Astronomy, and Science News PodcastAstronomy Daily – The Podcast is available on Apple Podcasts, Spotify, Google Podcasts, YouTube and wherever you get podcasts from:Apple Podcasts: https://podcasts.apple.com/us/podcast/astronomy-daily-the-podcast/id1642258990 Spotify: https://open.spotify.com/show/2kPF1ABBW2rCrjDlU2CWLW Or stream from our websites at www.spacenuts.io or our HQ at www.bitesz.com Commercial Free Premium version available with a Space Nuts subscription via Supercast only. Details: https://spacenuts.supercast.com/ If you'd like to find out more about the stories featured in today's show, you can read today's edition of the Astronomy Daily Newsletter at any of our websites – www.spacenuts.io , www.bitesz.com or go directly to www.astronomydaily.io – subscribe and get the new edition delivered to your mailbox or RSS reader every day….it's free from us to you.Please subscribe to the podcast and if you have a moment, a quick review would be most helpful. Thank you…Please show our sponsor some love. Looking to buy a domain name and establish yourself online for not very much money? Then use the folks we trust all our domains too… NameCheap…and help support the show. To find out more visit www.spacenutspodcast.com/namecheap - thank you.#space #astronomy #science #podcast #astronomydaily #spacenuts #spacetime

Tycho Brahe var i sine observationer naturligvis begrænset af sine instrumenters relativt lave nøjagtighed i slutningen af 1500-tallet. Men han formåede alligevel at samle vældig imponerende data – ikke mindst pga. sin omhyggelighed og sin vedholdenhed. Vi er taget over på Hven for at besøge hans observatorie og få en fornemmelse af omgivelserne hvor han arbejdede – og så skal vi også dykke ned i hvordan Tycho Brahe arbejdede. Han betragtes nemlig som en af grundlæggerne af den observerende astronomi, og gjorde store landvindinger når det handler om at skabe kolossale mængder af stadigt mere præcise data om stjerner og andre himmellegemer. Udover besøget her på Hven, hvor museumsguide Rasmus Trappe viser rundt, så har vi også talt med professor emeritus Erik Høg fra Niels Bohr Instituttet, der nok godt kan kaldes astrometriens grand old man. LINKS Tycho Brahe-museet på Hven (https://www.visithven.dk/tycho-brahe-museet/) Erik Høg-artikel om Tychos instrumenter og observationer (https://www.astro.ku.dk/~erik/xx/kv222-EH-Tycho.pdf) Erik Høg-artikel om astrometriens udvikling (https://www.astro.ku.dk/~erik/Astrometry400.pdf) Hipparcos-satellitten (https://sci.esa.int/web/hipparcos/) Gaia – det hidtil mest præcise og omfattende astrometriske instrument (https://www.cosmos.esa.int/web/gaia)

Astrometric Accelerations as Dynamical Beacons: Discovery and Characterization of HIP 21152 B, the First T-Dwarf Companion in the Hyades by Kyle Franson et al. on Monday 21 November Benchmark brown dwarf companions with well-determined ages and model-independent masses are powerful tools to test substellar evolutionary models and probe the formation of giant planets and brown dwarfs. Here, we report the independent discovery of HIP~21152~B, the first imaged brown dwarf companion in the Hyades, and conduct a comprehensive orbital and atmospheric characterization of the system. HIP~21152 was targeted in an ongoing high-contrast imaging campaign of stars exhibiting proper motion changes between Hipparcos and Gaia, and was also recently identified by Bonavita et al. (2022) and Kuzuhara et al. (2022). Our Keck/NIRC2 and SCExAO/CHARIS imaging of HIP~21152 revealed a comoving companion at a separation of $0.37^{primeprime}$ (16 au). We perform a joint orbit fit of all available relative astrometry and radial velocities together with the Hipparcos-Gaia proper motions, yielding a dynamical mass of $24^{+6}_{-4},mathrm{M_{Jup}}$, which is $1{-}2{sigma}$ lower than evolutionary model predictions. Hybrid grids that include the evolution of cloud properties best reproduce the dynamical mass. We also identify a comoving wide-separation ($1837^{primeprime}$ or $7.9 times 10^4 , mathrm{au}$) early-L dwarf with an inferred mass near the hydrogen-burning limit. Finally, we analyze the spectra and photometry of HIP~21152~B using the Saumon & Marley (2008) atmospheric models and a suite of retrievals. The best-fit grid-based models have $f_{mathrm{sed}}=2$, indicating the presence of clouds, $T_{mathrm{eff}}=1400 , mathrm{K}$, and $log{g}=4.5 , mathrm{dex}$. These results are consistent with the object's spectral type of $mathrm{T0pm1}$. As the first benchmark brown dwarf companion in the Hyades, HIP~21152~B joins the small but growing number of substellar companions with well-determined ages and dynamical masses. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.09840v1

Memorias: http://bit.ly/deo-memorias2 Temas: TESS descubre un nuevo planeta similar a Neptuno. Los muones y los ciclones. Los escritos de Hipparcos. ¿Qué tan dañinas son las supernovas cercanas para la vida en la Tierra?. Pulsos de polvo estelar observados por JWST. Realizan: Adriana Araujo (U. Sergio Arboleda), German Chaparro, Juan C. Muñoz, Esteban Silva, Lauren Flor, Pablo Cuartas, Jorge I. Zuluaga (Instituto de Física de la Universidad de Antioquia). Dirige: Jorge I. Zuluaga, Profesor Titular del Pregrado de Astronomía, U. de A. Produce y Edita: Jhossua Giraldo, Pregrado de Astronomía U. de A.

3-D selection of 167 sub-stellar companions to nearby stars by Fabo Feng et al. on Wednesday 14 September We analyze 5108 AFGKM stars with at least five high precision radial velocity points as well as Gaia and Hipparcos astrometric data utilizing a novel pipeline developed in previous work. We find 914 radial velocity signals with periods longer than 1000,d. Around these signals, 167 cold giants and 68 other types of companions are identified by combined analyses of radial velocity, astrometry, and imaging data. Without correcting for detection bias, we estimate the minimum occurrence rate of the wide-orbit brown dwarfs to be 1.3%, and find a significant brown dwarf valley around 40 $M_{rm Jup}$. We also find a power-law distribution in the host binary fraction beyond 3 au similar to that found for single stars, indicating no preference of multiplicity for brown dwarfs. Our work also reveals nine sub-stellar systems (GJ 234 B, GJ 494 B, HD 13724 b, HD 182488 b, HD 39060 b and c, HD 4113 C, HD 42581 d, HD 7449 B, and HD 984 b) that have previously been directly imaged, and many others that are observable at existing facilities. Depending on their ages we estimate that an additional 10-57 sub-stellar objects within our sample can be detected with current imaging facilities, extending the imaged cold (or old) giants by an order of magnitude. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2208.12720v3

3-D selection of 167 sub-stellar companions to nearby stars by Fabo Feng et al. on Wednesday 14 September We analyze 5108 AFGKM stars with at least five high precision radial velocity points as well as Gaia and Hipparcos astrometric data utilizing a novel pipeline developed in previous work. We find 914 radial velocity signals with periods longer than 1000,d. Around these signals, 167 cold giants and 68 other types of companions are identified by combined analyses of radial velocity, astrometry, and imaging data. Without correcting for detection bias, we estimate the minimum occurrence rate of the wide-orbit brown dwarfs to be 1.3%, and find a significant brown dwarf valley around 40 $M_{rm Jup}$. We also find a power-law distribution in the host binary fraction beyond 3 au similar to that found for single stars, indicating no preference of multiplicity for brown dwarfs. Our work also reveals nine sub-stellar systems (GJ 234 B, GJ 494 B, HD 13724 b, HD 182488 b, HD 39060 b and c, HD 4113 C, HD 42581 d, HD 7449 B, and HD 984 b) that have previously been directly imaged, and many others that are observable at existing facilities. Depending on their ages we estimate that an additional 10-57 sub-stellar objects within our sample can be detected with current imaging facilities, extending the imaged cold (or old) giants by an order of magnitude. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2208.12720v3

3-D selection of 167 sub-stellar companions to nearby stars by Fabo Feng et al. on Wednesday 14 September We analyze 5108 AFGKM stars with at least five high precision radial velocity points as well as Gaia and Hipparcos astrometric data utilizing a novel pipeline developed in previous work. We find 914 radial velocity signals with periods longer than 1000,d. Around these signals, 167 cold giants and 68 other types of companions are identified by combined analyses of radial velocity, astrometry, and imaging data. Without correcting for detection bias, we estimate the minimum occurrence rate of the wide-orbit brown dwarfs to be 1.3%, and find a significant brown dwarf valley around 40 $M_{rm Jup}$. We also find a power-law distribution in the host binary fraction beyond 3 au similar to that found for single stars, indicating no preference of multiplicity for brown dwarfs. Our work also reveals nine sub-stellar systems (GJ 234 B, GJ 494 B, HD 13724 b, HD 182488 b, HD 39060 b and c, HD 4113 C, HD 42581 d, HD 7449 B, and HD 984 b) that have previously been directly imaged, and many others that are observable at existing facilities. Depending on their ages we estimate that an additional 10-57 sub-stellar objects within our sample can be detected with current imaging facilities, extending the imaged cold (or old) giants by an order of magnitude. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2208.12720v3

3-D selection of 167 sub-stellar companions to nearby stars by Fabo Feng et al. on Wednesday 14 September We analyze 5108 AFGKM stars with at least five high precision radial velocity points as well as Gaia and Hipparcos astrometric data utilizing a novel pipeline developed in previous work. We find 914 radial velocity signals with periods longer than 1000,d. Around these signals, 167 cold giants and 68 other types of companions are identified by combined analyses of radial velocity, astrometry, and imaging data. Without correcting for detection bias, we estimate the minimum occurrence rate of the wide-orbit brown dwarfs to be 1.3%, and find a significant brown dwarf valley around 40 $M_{rm Jup}$. We also find a power-law distribution in the host binary fraction beyond 3 au similar to that found for single stars, indicating no preference of multiplicity for brown dwarfs. Our work also reveals nine sub-stellar systems (GJ 234 B, GJ 494 B, HD 13724 b, HD 182488 b, HD 39060 b and c, HD 4113 C, HD 42581 d, HD 7449 B, and HD 984 b) that have previously been directly imaged, and many others that are observable at existing facilities. Depending on their ages we estimate that an additional 10-57 sub-stellar objects within our sample can be detected with current imaging facilities, extending the imaged cold (or old) giants by an order of magnitude. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2208.12720v3

Combining Hipparcos and Gaia data for the study of binaries: the BINARYS tool by A. Leclerc et al. on Sunday 11 September Orbital motion in binary and planetary systems is the main source of precise stellar and planetary mass measurements, and joint analysis of data from multiple observational methods can both lift degeneracies and improve precision. We set out to measure the masses of individual stars in binary systems using all the information brought by the Hipparcos and Gaia absolute astrometric missions. We present BINARYS, a tool which uses the Hipparcos and Gaia absolute astrometric data and combines it with relative astrometry and/or radial velocity measurements to determine the orbit of a binary system. It rigorously combines the Hipparcos and Gaia data (here EDR3), and it can use the Hipparcos Transit Data as needed for binaries where Hipparcos detect significant flux from the secondary component. It also support the case where Gaia resolved the system, giving an astrometric solution for both components. We determine model-independent individual masses for the first time for three systems: the two mature binaries Gl~494 ($M_1=0.584 pm 0.003 M_{odot}$ and $M_2=87 pm 1 M_{textrm{Jup}}$) and HIP~88745 ($M_1=0.96 pm 0.02 M_{odot}$ and $M_2= 0.60^{+ 0.02 }_{- 0.01 } M_{odot}$), and the younger AB Dor member GJ~2060 ($M_1=0.60 ^{+ 0.06}_{- 0.05} M_{odot}$ and $M_2=0.45 ^{+ 0.06}_{- 0.05}M_{odot}$). The latter provides a rare test of evolutionary model predictions at young ages in the low stellar-mass range and sets a lower age limit of 100~Myr for the moving group. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.04210v1

Cepheïden zijn speciale gevallen onder de variabele sterren. Ze kunnen ons vertellen hoe ver een object van ons vandaan staat. De Hipparcos satelliet: https://en.wikipedia.org/wiki/Hipparcos (https://en.wikipedia.org/wiki/Hipparcos)

Conoce la historia de las dos misiones de la Agencia Espacial Europea que están cartografiando la Vía Láctea. Conoce además la anécdota de las leyes espaciales canadienses, la cultura espacial de la Piedra Negra, y el desafío de este episodio. Escríbeme a laika.podcast@gmail.com. / Sígueme en instagram @laika.podcast

In Folge 49 reden wir über den Übergang zu Unterriesen. Ok, zuerst reden wir ein bisschen über Schnupfen. Und Fred Hoyle. Und das James-Webb-Teleskop. Und nicht über die neue Hubble-Entdeckung. Aber dann geht es um Unterriesen. Das ist eine ganz spezielle Phase im Leben eines Sterns und man hat durch die Beobachtung dieser Objekte herausgefunden, dass die Milchstraße älter ist als gedacht. Außerdem beantworten wir immer Fragen, zum Beispiel darüber, was am schwersten zu entdecken ist. Und ob es Berge gibt, die so hoch sind, dass sie aus der Atmosphäre ihrer Planeten herausragen können. Mit Evi reden wir in “Neues von der Sternwarte” über das astronomische Praktium. Und demnächst treiben wir uns in Vorarlberg rum und man kann uns dabei zusehen.

Canopus ist der zweithellste Stern am Nachthimmel. Und neben jeder Menge Mythologie hat der Stern auch Astronomie zu bieten. Und arbeitet ab und zu als Steuermann für Raumsonden. Alles über Canopus gibt es in der neuen Folge der Sternengeschichten.

Ecco la puntata 05 della stagione 14 di AstronautiCAST. Tutti i link e gli approfondimenti sono disponibili nelle note dell'episodio.

Sapete cos’è l’ESA? È l’Agenzia Spaziale Europea. Chissà perché se ne parla poco: eppure le sue missioni sono state tante!La sonda Cos-B che ha analizzato le emissioni di raggi gamma dell'universo.. La Missione Giotto, per raggiungere e studiare la Cometa di Halley.. La Missione di astrometria spaziale Hipparcos e il successivo Atlante Stellare del Millennio, un atlante di tutto il cielo realizzato con i dati raccolti..E le collaborazioni con la NASA: come il Telescopio Spaziale Hubble o la Missione Cassini-Huygens, che ha raggiunto Saturno e la sua luna Titano..O la Missione Double Star, in collaborazione con la Cina.Oggi l’Agenzia Spaziale Europea è una delle agenzie spaziali più importanti del mondo: scopriamo insieme la sua storia e le sue missioni.

Die markanten Sterne der Plejaden haben die Menschen schon seit Jahrtausenden beschäftigt. Früher haben wir uns Geschichten über Götter, Dämonen und Helden über sie erzählt. Heute finden wir dort wissenschaftliche Kontroversen und vielleicht ganz neues Wissen. Mehr dazu gibt es heute im Sternengeschichten-Podcast

La masse de la jeune exoplanète découverte en 2008 autour de beta Pictoris vient d'être mesurée assez précisément grâce à l'observation minutieuses des mouvements de beta Pictoris par le télescope Gaia et son lointain prédécesseur Hipparcos.

Die Frage, "wieviel Sternlein stehen", ist gar nicht so einfach zu beantworten. Schon früh beschäftigte sich die Menschheit damit, die sichtbaren Sterne zu katalogisieren und obwohl die moderne Raumfahrt es später durch Missionen wie Hipparcos schaffte, dieses Wissen spürbar auszudehnen, weiß man heute vor allem dass man eigentlich nichts weiß. Die Gaia-Mission hat sich nun zum Ziel gesetzt, einen neuen Sternenkatalog zu schaffen, der deutlich umfangreicher und vor allem viel genauer sein soll als alle bisherigen Verzeichnisse. Neben der genauen Position und Entfernung werden dabei auch die dem Licht entlockbaren Informationen über die Zusammensetzung der Sonnen mit aufgenommen. Auf 100 Milliarden Sterne wird unsere Galaxie grob geschätzt, gut ein Prozent davon möchte Gaia vermessen. Mit großer Präzision wurde für die Mission ein Kamerasystem geschaffen, das über einen Zeitraum von ca. 5 Jahren alle sichtbaren Sterne der Milchstraße bis zu 70 mal erfassen soll. Der daraus resultierende Sternenkatalog wird in der Zukunft die Basis für viele neue Missionen und neue wissenschaftliche Erkenntnisse über die Beschaffenheit unseres Universums sein.

Transcript: Distance is a fundamental stellar property. Without knowing distance it’s impossible to measure the luminosity or absolute brightness of a star, and so without measuring distance it’s impossible to know the true nature of a star seen in the sky whose flux is measured whether it’s a giant star, a main sequence star, or a dwarf. Parallax is difficult to measure from the ground. Typical image sizes from ground-based observatories are about an arcsecond or fraction of an arcsecond. Image positions can be measured to about a tenth of that, and so that only allows the possibility of measuring parallaxes of a few tenths of an arcsecond which limits us to distances of a few parsecs, the nearest dozen or so stars. From space the image sizes go down by a factor of ten or twenty to 0.1 arcseconds or 0.05 arcseconds. The position accuracies can be measured ten times better than that to a hundredth of an arcsecond or less which opens up a distance range of a hundred parsecs. There are twenty-five thousand stars within a hundred parsecs. In 1989 ESA launched the Hipparcos satellite which used a highly elliptical orbit and several years of observations to directly measure the parallax of a hundred thousand stars. Thus we have the distances of a large stellar population sample within a few hundred lightyears of the Sun.

Transcript -- A route map to the stars. The Hipparcos satellite measured the position of stars with better precision than ever before.

A route map to the stars. The Hipparcos satellite measured the position of stars with better precision than ever before.

Transcript -- A route map to the stars. The Hipparcos satellite measured the position of stars with better precision than ever before.

A route map to the stars. The Hipparcos satellite measured the position of stars with better precision than ever before.

Young stars close to the sun (within 100 pc) yield an interesting sample in many respects: They are relatively bright and because of their close distance we can resolve the surroundings of these stars by using adaptive optics on 8 to 10 m class telescopes (e.g. VLT or Keck). In the K-band the achievable angular resolution is about 50 mas which corresponds to 5 AU at a star closer than 100 pc; 5 AU is about the distance between the Sun and Jupiter. This possibility can be used to study surrounding material such as disks made up of gas and dust as well as stellar and substellar companions. A sample consisting of young stars in the solar vicinity and in an evolutionary stage between the classical T Tauri phase with a disk and the zero-age main sequence can be provided by the catalog of flare stars and related objects compiled by Gershberg et al. (1999) because young stars are often variable and exhibit large eruptions (flares). In a first step we need to verify that these stars are indeed young and did not come to lie above the main sequence in a Hertzsprung-Russell diagram because they are old or unresolved binaries or multiples. Therefore, we have taken spectra of 223 stars lying above the main sequence (of the 463 stars of the sample). The distances to these stars were measured (in most cases by Hipparcos) and they are located at a few to 100 pc. The goal was to detect lithium absorption at 6708 A which all young stars have in common. In addition to the detection of lithium, we want to identify other age indicators such as filling in or emission of the Halpha -, the magnesium Ib- and the calcium lines. The G- and K-type stars of the northern hemisphere were also observed with high resolution, and high signal-to-noise ratio spectroscopy to study these objects with methods of spectral synthesis analysis to determine the surface gravity, the chemical composition, and the temperature. The age determination of these 223 stars lead to a value between 10 Myr and the zero-age main sequence, they are indeed nearby and 17 stars are clearly pre-main sequence. In the course of this work, we discovered the closest pre-main sequence star (HIP 108405 A, 10+-10 Myrs at a distance of 16.1pc). The star is younger than GJ 182 (27 pc, 20+-10 Myrs) which held the record up to now. A planet with a mass of 5 MJup in orbit of a (for this sample) typical M-star, would have an apparent magnitude in the K-band of 14.5 to 17.5 mag at a distance of 16 pc. This would lead to a magnitude difference DeltaK of 8 to 11 mag between the star and the companion, which could be detected with 8 to 10 m class telescopes at a separation of 1" or a projected separation of 16 AU. All newly discovered young flare stars were imaged using NAOS/CONICA to search for distant companions. Depending on the space motion of the stars, they have to be reobserved in one or more years to distinguish comoving companions from stagnant background stars. In this work we have measured radial velocity variations of young stars for the first time using the échelle spectrograph of the Thüringer Landessternwarte. In these measurements one can see the problems of such an investigation, such as variability caused by activity and stellar spots. But one can also see that it is in principle possible to detect planets around active young stars. To verify the results and to measure longer rotation periods, we have to observe these stars for another season.

A refined theory of line formation for neutral and singly-ionized iron in the atmospheres of cool stars in presented. It accounts for departures from local thermodynamic equilibrium –so-called non-LTE effects –an d serves the derivation of spectroscopic stellar gravities “g” via the ionization equilibrium constraint. The respective influence of various model assumptions (atomic data sets including photo-ionization cross-sections and transition probabilities; the efficiency of collisions with neutral particles and so forth) is investigated by means of extensive profile analyses of iron lines in the optical spectrum of the Sun. Due to the large scatter among laboratory transition probabilities the main free parameter of the model –th e strength of collisions with neutral hydrogen SH which govern excitation and ionization –can not be determined by inspecting the Sun alone. Depending on the choice of SH non-LTE effects in neutral iron range from 0.01 dex to 0.10 dex in the logarithmic abundance, while singly-ionized iron follows LTE. To calibrate SH a set of local standard stars is employed whose surface gravities can be inferred from astrometry (the Hipparcos satellite mission) on a given temperature scale. With the exception of the metal-rich standard star Procyon for which a mild temperature correction is needed to fulfil the ionization balance, excellent consistency is obtained for the metal-poor calibration stars in various evolutionary stages if the Balmer profile temperatures are combined with an SH of 3. Departures from LTE are moderate and amount to 0.1 dex in log g at most. The correct choice of the van-der-Waals damping constants is generally more important for these stars than non-LTE. The long-standing discrepancy with respect to an independent spectroscopic gravity scale discussed in the literature can be fully resolved. Recent modifications to the formation theory of Balmer lines are implemented, but do not yield consistent results: the temperature of the Sun is not recovered, the observed Balmer line profiles of metal-poor stars are not reproduced. The devised model is applied to two extreme objects, the most metal-poor star known (100 000 times less metals than the Sun) and a so-called r-process star, both recently identified in wide-angle sky survey. Here non-LTE effects are much more pronounced (0.3 dex in log g ). This result emphasizes the importance of considering departures from LTE for iron, especially when it comes to studying giant stars in the Galactic halo.