Увійти

Готові списки джерел за темами / Star masses / Статті в журналах

Статті в журналах з теми "Star masses"

Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Star masses.

Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 28 січня 2023

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Star masses".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.

1

Nice, David. "Neutron star masses." Proceedings of the International Astronomical Union 8, S291 (August 2012): 146. http://dx.doi.org/10.1017/s1743921312023423.

Повний текст джерела

Анотація:

AbstractNeutron star masses can be inferred from observations of binary pulsar systems, particularly by the measurement of relativistic phenomena within these orbits. The observed distribution of masses can be used to infer or constrain the equation of state for nuclear matter and to study astrophysical processes such as supernovae and binary star evolution. In this talk, I will review our present understanding of the neutron star mass distribution with an emphasis on the observational data.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Maddox, John. "Star masses and bayesian probability." Nature 371, no. 6499 (October 1994): 649. http://dx.doi.org/10.1038/371649a0.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Kruckow, Matthias U. "Masses of double neutron star mergers." Astronomy & Astrophysics 639 (July 2020): A123. http://dx.doi.org/10.1051/0004-6361/202037519.

Повний текст джерела

Анотація:

Aims. I aim to explain the mass discrepancy between the observed double neutron-star binary population by radio pulsar observations and gravitational-wave observation. Methods. I performed binary population synthesis calculations and compared their results with the radio and the gravitational-wave observations simultaneously. Results. Simulations of binary evolution were used to link different observations of double neutron star binaries with each other. I investigated the progenitor of GW190425 in more detail. A distribution of masses and merger times of the possible progenitors is presented. Conclusions. A mass discrepancy between the radio pulsars in the Milky Way with another neutron star companion and the inferred masses from gravitational-wave observations of those kind of merging systems is naturally found in binary evolution.

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Rocha, Lívia S., Antônio Bernardo, Jorge E. Horvath, Rodolfo Valentim, and Marcio G. B. Avellar. "The distribution of neutron star masses." Astronomische Nachrichten 340, no. 9-10 (November 2019): 957–63. http://dx.doi.org/10.1002/asna.201913743.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Sbisà, Fulvio, Pedro O. Baqui, Tays Miranda, Sergio E. Jorás, and Oliver F. Piattella. "Neutron star masses in R2-gravity." Physics of the Dark Universe 27 (January 2020): 100411. http://dx.doi.org/10.1016/j.dark.2019.100411.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Waltham, David. "Star Masses and Star-Planet Distances for Earth-like Habitability." Astrobiology 17, no. 1 (January 2017): 61–77. http://dx.doi.org/10.1089/ast.2016.1518.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Neumayer, Nadine. "Nuclear Star Clusters." Proceedings of the International Astronomical Union 12, S316 (August 2015): 84–90. http://dx.doi.org/10.1017/s1743921316007018.

Повний текст джерела

Анотація:

AbstractThe centers of galaxies host two distinct, compact components: massive black holes and nuclear star clusters. Nuclear star clusters are the densest stellar systems in the universe, with masses of ~ 107M⊙and sizes of ~ 5pc. They are almost ubiquitous at the centres of nearby galaxies with masses similar to, or lower than the Milky Way. Their occurrence both in spirals and dwarf elliptical galaxies appears to be a strong function of total galaxy light or mass. Nucleation fractions are up to 100% for total galaxy magnitudes of MB= −19mag or total galaxy luminosities of about LB= 1010L⊙and falling nucleation fractions for both smaller and higher galaxy masses. Although nuclear star clusters are so common, their formation mechanisms are still under debate. The two main formation scenarios proposed are the infall and subsequent merging of star clusters and the in-situ formation of stars at the center of a galaxy. Here, I review the state-of-the-art of nuclear star cluster observations concerning their structure, stellar populations and kinematics. These observations are used to constrain the proposed formation scenarios for nuclear star clusters. Constraints from observations show, that likely both cluster infall and in-situ star formation are at work. The relative importance of these two mechanisms is still subject of investigation.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Hensler, Gerhard, Patrick Steyrleithner, and Simone Recchi. "Star formation at low rates - the impact of lacking massive stars on stellar feedback." Proceedings of the International Astronomical Union 11, S321 (March 2016): 99–101. http://dx.doi.org/10.1017/s1743921316011261.

Повний текст джерела

Анотація:

AbstractDue to their low masses dwarf galaxies experience low star-formation rates resulting in stellar cluster masses insufficient to fill the initial mass function (IMF) to the uppermost mass. Numerical simulations usually do not account for the completeness of the IMF, but treat a filed IMF by numbers, masses, and stellar feedback by fractions. To ensure that only entire stars are formed, we consider an IMF filled from the lower-mass regime and truncated where at least one entire massive star is formed.By 3D simulations we investigate the effects of two possible IMFs on the evolution of dwarf galaxies: filled vs. truncated IMF. For the truncated IMF the star-formation self-regulation is suppressed, while the energy release by typeII supernovae is larger, both compared to the filled IMF. Moreover, the abundance ratios of particular elements yielded from massive and intermediate-mass stars differ significantly between the two IMF distributions.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Fahrion, K., M. Lyubenova, G. van de Ven, M. Hilker, R. Leaman, J. Falcón-Barroso, A. Bittner, et al. "Diversity of nuclear star cluster formation mechanisms revealed by their star formation histories." Astronomy & Astrophysics 650 (June 2021): A137. http://dx.doi.org/10.1051/0004-6361/202140644.

Повний текст джерела

Анотація:

Nuclear star clusters (NSCs) are the densest stellar systems in the Universe and are found in the centres of all types of galaxies. They are thought to form via mergers of star clusters such as ancient globular clusters (GCs) that spiral to the centre as a result of dynamical friction or through in situ star formation directly at the galaxy centre. There is evidence that both paths occur, but the relative contribution of either channel and their correlation with galaxy properties are not yet constrained observationally. Our aim was to derive the dominant NSC formation channel for a sample of 25 nucleated galaxies, mostly in the Fornax galaxy cluster, with stellar masses between Mgal ∼ 108 and 1010.5 M⊙ and NSC masses between MNSC ∼ 105 and 108.5 M⊙. Using Multi-Unit Spectroscopic Explorer data from the Fornax 3D survey and the ESO archive, we derived star formation histories, mean ages, and metallicities of NSCs, and compared them to the host galaxies. In many low-mass galaxies, the NSCs are significantly more metal poor than their hosts, with properties similar to GCs. In contrast, in the massive galaxies we find diverse star formation histories and cases of ongoing or recent in situ star formation. Massive NSCs (> 107 M⊙) occupy a different region in the mass–metallicity diagram than lower-mass NSCs and GCs, indicating a different enrichment history. We find a clear transition of the dominant NSC formation channel with both galaxy and NSC mass. We hypothesise that while GC accretion forms the NSCs of the dwarf galaxies, central star formation is responsible for the efficient mass build up in the most massive NSCs in our sample. At intermediate masses both channels can contribute. The transition between these formation channels seems to occur at galaxy masses Mgal ∼ 109 M⊙ and NSC masses MNSC ∼ 107 M⊙.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Lee, Chang-Hwan. "Formation and Evolution of Neutron Star Binaries: Masses of Neutron Stars." EPJ Web of Conferences 20 (2012): 04002. http://dx.doi.org/10.1051/epjconf/20122004002.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Simon, M. "Dynamical masses of pms stars in the taurus star formation region." EAS Publications Series 64 (2013): 141–44. http://dx.doi.org/10.1051/eas/1364020.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Panagia, Nino, and Guido De Marchi. "Star Formation as Seen by Low Mass Stars." Acta Polytechnica CTU Proceedings 1, no. 1 (December 4, 2014): 113–17. http://dx.doi.org/10.14311/app.2014.01.0113.

Повний текст джерела

Анотація:

Using the Hubble Space Telescope (HST) we have characterised and compared the physical properties of a large sample of pre-main sequence (PMS) stars spanning a wide range of masses (0:5 - 4M<sub>ʘ</sub>), metallicities (0:1 - 1 Z<sub>ʘ</sub>) and ages (0:5 - 30 Myr). This is presently the largest and most homogeneous sample of PMS objects with known physical properties. The main results of this ongoing study are briefly summarised here.

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Harpaz, Amos. "Lower Limit for NPN's Masses." Symposium - International Astronomical Union 131 (1989): 454. http://dx.doi.org/10.1017/s007418090013894x.

Повний текст джерела

Анотація:

The lowest mass observed for a nucleus of a planetary nebula (NPN) is about 0.55 M⊙ (Weidemann and Koester, 1983, Schonberner, 1983). Hence, Lower mass WD's should have been produced without going through the phase of a visible PN ejection. Recently, Harpaz et al. (1987), have shown that very low mass WD's (up to 0.45 M⊙) can be formed by a single star evolution from red giant branch (RGB) stars, due to mass loss along the RGB. It turns out that WD's in mass range of 0.46–0.55 M⊙ formed by a single star evolution should be formed from the AGB, without an observable PN.

Стилі APA, Harvard, Vancouver, ISO та ін.

14

CHENG, ZHENG, CHENGMIN ZHANG, and ALI TAANI. "MONTE CARLO SIMULATION OF NEUTRON STAR MASSES." International Journal of Modern Physics: Conference Series 23 (January 2013): 157–60. http://dx.doi.org/10.1142/s2010194513011227.

Повний текст джерела

Анотація:

We perform a Monte Carlo simulation to investigate the distribution and evolution of 66 mass measured pulsars. We get the best fits to the distribution at 1.35 ± 0.27M⨀ (1σ confidence level). In addition, we notice bimodal distributions in 1.34 ± 0.15M⨀ and 1.48 ± 0.53M⨀, this can be led to the idea that radio pulsars in binary systems have recycled. Thus we divide the data according to the characteristic spin period into two groups, millisecond pulsars (MSPs), P Spin ≤ 20 ms and less recycled pulsars P Spin ≥ 20 ms , respectively. We show that the distributions of MSPs at 1.42 ± 0.36M⨀, and 1.32 ± 0.18M⨀ for less recycled pulsars. As such, the mass of MSPs are heavier than those in less recycled pulsars by ~ 0.1M⨀, since they accreting material from their companions. On the other hand, the formation of heavier pulsars from the accretion induced collapse of accreting white dwarfs, must be invoked.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Poole, T., K. O. Mason, G. Ramsay, J. E. Drew, and R. C. Smith. "The component star masses in RW Tri." Monthly Notices of the Royal Astronomical Society 340, no. 2 (April 2003): 499–508. http://dx.doi.org/10.1046/j.1365-8711.2003.06316.x.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Popov, Sergei, David Blaschke, Hovik Grigorian, and Mikhail Prokhorov. "Neutron star masses: dwarfs, giants and neighbors." Astrophysics and Space Science 308, no. 1-4 (March 20, 2007): 381–85. http://dx.doi.org/10.1007/s10509-007-9335-9.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Tian, Lanlan, and Shude Mao. "Determining neutron star masses using weak microlensing." Monthly Notices of the Royal Astronomical Society 427, no. 3 (November 20, 2012): 2292–97. http://dx.doi.org/10.1111/j.1365-2966.2012.22101.x.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Hochron, D. A., B. W. Lynn, and S. B. Selipsky. "An upper bound on Q-star masses." Classical and Quantum Gravity 10, no. 2 (February 1, 1993): 299–306. http://dx.doi.org/10.1088/0264-9381/10/2/011.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Amnuel, P. "Asymmetrical planetary nebulae and central star masses." Astrophysics and Space Science 225, no. 2 (1995): 275–87. http://dx.doi.org/10.1007/bf00613242.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Caspar, G., I. Rodríguez, P. O. Hess, and W. Greiner. "Vacuum fluctuation inside a star and their consequences for neutron stars, a simple model." International Journal of Modern Physics E 25, no. 04 (April 2016): 1650027. http://dx.doi.org/10.1142/s0218301316500270.

Повний текст джерела

Анотація:

Applying semi-classical quantum mechanics, the vacuum fluctuations within a star are determined, assuming a constant mass density and applying a monopole approximation. It is found that the density for the vacuum fluctuations does not only depend linearly on the mass density, as assumed in a former publication, where neutron stars up to 6 solar masses were obtained. This is used to propose a simple model on the dependence of the dark energy to the mass density, as a function of the radial distance [Formula: see text]. It is shown that stars with up to 200 solar masses can, in principle, be obtained. Though, we use a phenomenological model, it shows that in the presence of vacuum fluctuations stars with large masses can be stabilized and probably stars up to any mass can exist, which usually are identified as black holes.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Gallagher, John S., Tova M. Yoast-Hull, and Ellen G. Zweibel. "Lessons from comparisons between the nuclear region of the Milky Way and those in nearby spirals." Proceedings of the International Astronomical Union 9, S303 (October 2013): 61–65. http://dx.doi.org/10.1017/s1743921314000155.

Повний текст джерела

Анотація:

AbstractThe Milky Way appears as a typical barred spiral, and comparisons can be made between its nuclear region and those of structurally similar nearby spirals. Maffei 2, M83, IC 342 and NGC 253 are nearby systems whose nuclear region properties contrast with those of the Milky Way. Stellar masses derived from NIR photometery, molecular gas masses and star formation rates allow us to assess the evolutionary states of this set of nuclear regions. These data suggest similarities between nuclear regions in terms of their stellar content while highlighting significant differences in current star formation rates. In particular current star formation rates appear to cover a larger range than expected based on the molecular gas masses. This behavior is consistent with nuclear region star formation experiencing episodic variations. Under this hypothesis the Milky Way's nuclear region currently may be in a low star formation rate phase.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Pereira, M. E. S., A. Palmese, T. N. Varga, T. McClintock, M. Soares-Santos, J. Burgad, J. Annis та ін. "μ⋆ masses: weak-lensing calibration of the Dark Energy Survey Year 1 redMaPPer clusters using stellar masses". Monthly Notices of the Royal Astronomical Society 498, № 4 (7 вересня 2020): 5450–67. http://dx.doi.org/10.1093/mnras/staa2687.

Повний текст джерела

Анотація:

ABSTRACT We present the weak-lensing mass calibration of the stellar-mass-based μ⋆ mass proxy for redMaPPer galaxy clusters in the Dark Energy Survey Year 1. For the first time, we are able to perform a calibration of μ⋆ at high redshifts, z > 0.33. In a blinded analysis, we use ∼6000 clusters split into 12 subsets spanning the ranges 0.1 ≤ z < 0.65 and μ⋆ up to ${\sim} 5.5 \times 10^{13} \, \mathrm{M}_{\odot }$, and infer the average masses of these subsets through modelling of their stacked weak-lensing signal. In our model, we account for the following sources of systematic uncertainty: shear measurement and photometric redshift errors, miscentring, cluster-member contamination of the source sample, deviations from the Navarro–Frenk–White halo profile, halo triaxiality, and projection effects. We use the inferred masses to estimate the joint mass–μ⋆–z scaling relation given by $\langle M_{200c} | \mu _{\star },z \rangle = M_0 (\mu _{\star }/5.16\times 10^{12} \, \mathrm{M_{\odot }})^{F_{\mu _{\star }}} ((1+z)/1.35)^{G_z}$. We find $M_0= (1.14 \pm 0.07) \times 10^{14} \, \mathrm{M_{\odot }}$ with $F_{\mu _{\star }}= 0.76 \pm 0.06$ and Gz = −1.14 ± 0.37. We discuss the use of μ⋆ as a complementary mass proxy to the well-studied richness λ for: (i) exploring the regimes of low z, λ < 20 and high λ, z ∼ 1; and (ii) testing systematics such as projection effects for applications in cluster cosmology.

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Haas, M. R., and P. Anders. "Population synthesis from clustered star formation." Proceedings of the International Astronomical Union 5, S262 (August 2009): 347–48. http://dx.doi.org/10.1017/s1743921310003170.

Повний текст джерела

Анотація:

In recent years, a series of papers (Kroupa & Weidner 2003, Weidner & Kroupa 2004, Weidner & Kroupa 2005 and Weidner & Kroupa 2006, WK06 from now on) have proposed that the stellar content of an entire galaxy may not be well described by the same initial mass function (IMF) that describes the distribution of stellar masses in the star clusters, where these stars form. The reason is that star clusters also form with a cluster mass function (CMF), which is a power law with a power law index of ~−2. If the lowest mass clusters are of masses smaller than the physical upper mass limit for stars they will be deficient in high mass stars. Therefore, if the stellar content of all clusters is added together, making up the Integrated Galactic Initial Mass Function (IGIMF), the distribution of stellar masses may be steeper at the high mass end, depending on the exact shape of the CMF.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Davies, L. J. M., J. E. Thorne, S. Bellstedt, M. Bravo, A. S. G. Robotham, S. P. Driver, R. H. W. Cook та ін. "Deep Extragalactic VIsible Legacy Survey (DEVILS): evolution of the σSFR–M⋆ relation and implications for self-regulated star formation". Monthly Notices of the Royal Astronomical Society 509, № 3 (9 листопада 2021): 4392–410. http://dx.doi.org/10.1093/mnras/stab3145.

Повний текст джерела

Анотація:

ABSTRACT We present the evolution of the star formation dispersion–stellar mass relation (σSFR–M⋆) in the DEVILS D10 region using new measurements derived using the ProSpect spectral energy distribution fitting code. We find that σSFR–M⋆ shows the characteristic ‘U-shape’ at intermediate stellar masses from 0.1 < z < 0.7 for a number of metrics, including using the deconvolved intrinsic dispersion. A physical interpretation of this relation is the combination of stochastic star formation and stellar feedback causing large scatter at low stellar masses and AGN feedback causing asymmetric scatter at high stellar masses. As such, the shape of this distribution and its evolution encodes detailed information about the astrophysical processes affecting star formation, feedback and the lifecycle of galaxies. We find that the stellar mass that the minimum σSFR occurs evolves linearly with redshift, moving to higher stellar masses with increasing lookback time and traces the turnover in the star-forming sequence. This minimum σSFR point is also found to occur at a fixed specific star formation rate (sSFR) at all epochs (sSFR ∼ 10−9.6 Gyr−1). The physical interpretation of this is that there exists a maximum sSFR at which galaxies can internally self-regulate on the tight sequence of star formation. At higher sSFRs, stochastic stellar processes begin to cause galaxies to be pushed both above and below the star-forming sequence leading to increased SFR dispersion. As the Universe evolves, a higher fraction of galaxies will drop below this sSFR threshold, causing the dispersion of the low stellar mass end of the star-forming sequence to decrease with time.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Ryu, C. Y., C. H. Hyun, S. W. Hong, and B. K. Jennings. "Hadron masses in medium and neutron star properties." European Physical Journal A 24, no. 1 (February 18, 2005): 149–57. http://dx.doi.org/10.1140/epja/i2004-10133-6.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Thorsett, S. E., Z. Arzoumanian, M. M. McKinnon, and J. H. Taylor. "The masses of two binary neutron star systems." Astrophysical Journal 405 (March 1993): L29. http://dx.doi.org/10.1086/186758.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Podsiadlowski, Philipp, and Nigel M. Price. "Star formation and the origin of stellar masses." Nature 359, no. 6393 (September 1992): 305–7. http://dx.doi.org/10.1038/359305a0.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Yi-yan, Yang, Zhang Cheng-min, Wang De-hua, Pan Yuan-yue, and Zhou Zhu-wen. "A Statistical Study on Double Neutron Star Masses." Chinese Astronomy and Astrophysics 41, no. 4 (October 2017): 505–16. http://dx.doi.org/10.1016/j.chinastron.2017.11.003.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Podsiadlowski, Ph, and N. M. Price. "Star Formation and the Origin of Stellar Masses." International Astronomical Union Colloquium 137 (1993): 795–97. http://dx.doi.org/10.1017/s025292110001890x.

Повний текст джерела

Анотація:

AbstractWe present a new model to explain stellar mass distributions in different stellar environments. In our model, the protostar phase is terminated, when the protostellar core embedded in a molecular clump experiences a collision with another star or protostellar clump, which ejects the protostellar core from its parent clump. Such dynamical interactions are necessarily important, if stars preferentially form in dense clusters. We show that, in a simple model, the initial mass function approaches a simple, asymptotic form, which strongly resembles observed mass functions. The model has important consequences for star formation in different environments. We also discuss the implications of the model for our understanding of pre-main-sequence stellar evolution.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Pandey, A. K., D. C. Paliwal, and H. S. Mahra. "Star formation efficiency in clouds of various masses." Astrophysical Journal 362 (October 1990): 165. http://dx.doi.org/10.1086/169252.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Danilov, V. M., and A. F. Seleznev. "Dynamical estimates of gas—star complex total masses." Astronomical & Astrophysical Transactions 7, no. 2-3 (April 1995): 113–16. http://dx.doi.org/10.1080/10556799508205399.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Dessauges-Zavadsky, Miroslava, Antonio Cava, Valentina Tamburello, Daniel Schaerer, Lucio Mayer, Johan Richard, and Pablo G. Pérez González. "Massive star clusters in high-redshift star-forming galaxies seen at a 100 pc scale thanks to strong gravitational lensing." Proceedings of the International Astronomical Union 12, S316 (August 2015): 111–16. http://dx.doi.org/10.1017/s1743921315009035.

Повний текст джерела

Анотація:

AbstractHigh-resolution imaging reveals clumpy morphologies among z = 1 – 3 galaxies. Most of these galaxies are dominated by disk rotation, which led to conclude that the observed clumps are generated from disk fragmentation due to gravitational instability. Despite the kpc-scale resolution attained by the most advanced facilities and numerical simulations, these clumps are barely resolved at z > 1. Thanks to the stretching and magnification power provided by gravitational lensing, we reach the sub-kpc resolving power to unveil their physics. From our literature compilation of data, we show that without lensing there is a bias toward clumps with high masses and sizes. The high-redshift clumps identified in lensed galaxies have stellar masses 2 orders of magnitude lower and a median size of 250 pc. They resemble local star clusters observed in the most intensively star-forming galaxies. The clump masses and sizes observed in lensed galaxies agree with new simulations, which show that the Toomre instability criterion overestimates the clump masses by a factor of 5 – 6.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Neumayer, Nadine, and C. Jakob Walcher. "Are Nuclear Star Clusters the Precursors of Massive Black Holes?" Advances in Astronomy 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/709038.

Повний текст джерела

Анотація:

We present new upper limits for black hole masses in extremely late type spiral galaxies. We confirm that this class of galaxies has black holes with masses less than 106M⊙, if any. We also derive new upper limits for nuclear star cluster masses in massive galaxies with previously determined black hole masses. We use the newly derived upper limits and a literature compilation to study the low mass end of the global-to-nucleus relations. We find the following. (1) TheMBH-σrelation cannot flatten at low masses, but may steepen. (2) TheMBH-Mbulgerelation may well flatten in contrast. (3) TheMBH-Sersicnrelation is able to account for the large scatter in black hole masses in low-mass disk galaxies. Outliers in theMBH-Sersicnrelation seem to be dwarf elliptical galaxies. When plottingMBHversusMNCwe find three different regimes: (a) nuclear cluster dominated nuclei, (b) a transition region, and (c) black hole-dominated nuclei. This is consistent with the picture, in which black holes form inside nuclear clusters with a very low-mass fraction. They subsequently grow much faster than the nuclear cluster, destroying it when the ratioMBH/MNCgrows above 100. Nuclear star clusters may thus be the precursors of massive black holes in galaxy nuclei.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Rao, Suvrat, Georges Meynet, Patrick Eggenberger, Lionel Haemmerlé, Giovanni Privitera, Cyril Georgy, Sylvia Ekström, and Christoph Mordasini. "Star-planet interactions." Astronomy & Astrophysics 618 (October 2018): A18. http://dx.doi.org/10.1051/0004-6361/201833107.

Повний текст джерела

Анотація:

Context. When planets are formed from the protoplanetary disk and after the disk has dissipated, the evolution of their orbits is governed by tidal interactions, friction, and gravitational drag, and also by changes in the mass of the star and planet. These interactions may change the initial distribution of the distances between the planets and their host star by expanding the original orbit, by contracting it (which may cause an engulfment of the planet by the star), or by destroying the planet. Aims. We study the evolution of the orbit of a planet orbiting its host star under the effects of equilibrium tides, dynamical tides, drag (frictional and gravitational), and stellar mass loss. Methods. We used the Geneva stellar evolution code to compute the evolution of stars with initial masses of 1 and 1.5 M⊙ with different rotation rates at solar metallicity. The star is evolved from the pre-main-sequence (PMS) up to the tip of the red giant branch. We used these models as input for computing the evolution of the planetary orbits. We explored the effects of changing the planet masses (of 1 Earth mass up to 20 Jupiter masses), the distance between the planet and the star (of 0.015 and more than 3 au), the mass, and the spin of the star. We present results when only the equilibrium tide was accounted for and when both equilibrium and dynamical tides were accounted for. The expression for the dynamical tide is a frequency-averaged dissipation of tidally excited inertial waves, obtained from a piecewise homogeneous two-layer stellar model. Gravity wave damping was neglected. Results. Dynamical tides in convective zones have a significant effect on planetary orbits only during the PMS phase and only for fast-rotating stars. They have no significant effects during the PMS phase for initially slow-rotating stars and during the red giant branch phase, regardless of the initial rotation. In the plots of initial orbital distance versus planetary mass, we show the regions that lead to engulfment or any significant changes in the orbit. As a result of orbital evolution, a region near the star can become devoid of planets after the PMS phase. We call this zone the planet desert, and its extent depends sensitively on stellar rotation. An examination of the planet distribution as a function of distance to the host star and mass can provide constraints on current computations.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Rathjen, Tim-Eric, Thorsten Naab, Philipp Girichidis, Stefanie Walch, Richard Wünsch, Frantis̆ek Dinnbier, Daniel Seifried, Ralf S. Klessen, and Simon C. O. Glover. "SILCC VI – Multiphase ISM structure, stellar clustering, and outflows with supernovae, stellar winds, ionizing radiation, and cosmic rays." Monthly Notices of the Royal Astronomical Society 504, no. 1 (March 27, 2021): 1039–61. http://dx.doi.org/10.1093/mnras/stab900.

Повний текст джерела

Анотація:

ABSTRACT We present simulations of the multiphase interstellar medium (ISM) at solar neighbourhood conditions including thermal and non-thermal ISM processes, star cluster formation, and feedback from massive stars: stellar winds, hydrogen ionizing radiation computed with the novel treeray radiative transfer method, supernovae (SN), and the injection of cosmic rays (CR). N-body dynamics is computed with a 4th-order Hermite integrator. We systematically investigate the impact of stellar feedback on the self-gravitating ISM with magnetic fields, CR advection and diffusion, and non-equilibrium chemical evolution. SN-only feedback results in strongly clustered star formation with very high star cluster masses, a bi-modal distribution of the ambient SN densities, and low volume-filling factors (VFF) of warm gas, typically inconsistent with local conditions. Early radiative feedback prevents an initial starburst, reduces star cluster masses and outflow rates. Furthermore, star formation rate surface densities of $\Sigma _{\dot{M}_\star } = 1.4-5.9 \times 10^{-3}$$\mathrm{M}_\odot \, \mathrm{yr}^{-1}\, \mathrm{kpc}^{-2}$, VFFwarm = 60–80 per cent as well as thermal, kinetic, magnetic, and cosmic ray energy densities of the model including all feedback mechanisms agree well with observational constraints. On the short, 100 Myr, time-scales investigated here, CRs only have a moderate impact on star formation and the multiphase gas structure and result in cooler outflows, if present. Our models indicate that at low gas surface densities SN-only feedback only captures some characteristics of the star-forming ISM and outflows/inflows relevant for regulating star formation. Instead, star formation is regulated on star cluster scales by radiation and winds from massive stars in clusters, whose peak masses agree with solar neighbourhood estimates.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Cox, Arthur N. "Horizontal Branch Evolution and RR Lyrae Star Pulsation." Highlights of Astronomy 10 (1995): 590–93. http://dx.doi.org/10.1017/s1539299600012193.

Повний текст джерела

Анотація:

For many years there has been a confrontation between stellar evolution and pulsation theories concerning the masses, luminosities, and compositions of the horizontal branch RR Lyrae variables. Masses obtained by Cox, Hodson & Clancy (CHC, 1983) were very low, but Kovacs (1985) and later Kovacs & Buchler (1988) suggested somewhat larger ones. Even later Simon & Cox (1991) verified CHC results, though still using the Los Alamos opacities. Petersen (1991, 1992) has also discussed this mass problem in some detail. The persistent discrepancy of 0.1 Mʘ or more between the evolution and pulsation masses was mostly ignored because neither theory could find any significant flaw in its analysis. Cox (1991), Kovacs, Buchler & Marom (1991), and Kovacs, Buchler, Marom, Iglesias & Rogers (1992) finally showed that larger double-mode pulsation masses, are consistent with evolution calculations to reproduce color-magnitude diagrams of globular clusters. Evolution tracks by many for years, especially the recent ones by Lee, Demarque & Zinn (1990), did require a much lower primordial helium abundance near the big bang value near Y = 0.23, and now this value, slightly enhanced by deep convection dredge-up in the earlier red giant stage, is also found to be appropriate for pulsation studies.

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Menezes, Débora Peres. "A Neutron Star Is Born." Universe 7, no. 8 (July 26, 2021): 267. http://dx.doi.org/10.3390/universe7080267.

Повний текст джерела

Анотація:

A neutron star was first detected as a pulsar in 1967. It is one of the most mysterious compact objects in the universe, with a radius of the order of 10 km and masses that can reach two solar masses. In fact, neutron stars are star remnants, a kind of stellar zombie (they die, but do not disappear). In the last decades, astronomical observations yielded various contraints for neutron star masses, and finally, in 2017, a gravitational wave was detected (GW170817). Its source was identified as the merger of two neutron stars coming from NGC 4993, a galaxy 140 million light years away from us. The very same event was detected in γ-ray, X-ray, UV, IR, radio frequency and even in the optical region of the electromagnetic spectrum, starting the new era of multi-messenger astronomy. To understand and describe neutron stars, an appropriate equation of state that satisfies bulk nuclear matter properties is necessary. GW170817 detection contributed with extra constraints to determine it. On the other hand, magnetars are the same sort of compact object, but bearing much stronger magnetic fields that can reach up to 1015 G on the surface as compared with the usual 1012 G present in ordinary pulsars. While the description of ordinary pulsars is not completely established, describing magnetars poses extra challenges. In this paper, I give an overview on the history of neutron stars and on the development of nuclear models and show how the description of the tiny world of the nuclear physics can help the understanding of the cosmos, especially of the neutron stars.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Puetter, R. C. "Star Clusters in Quasars: Bloated Stars as Broad Emission Line Clouds." Symposium - International Astronomical Union 134 (1989): 137–38. http://dx.doi.org/10.1017/s0074180900140653.

Повний текст джерела

Анотація:

Many scenarios of the evolution of star clusters in the centers of galaxies involve the formation of a central supermassive object. Since black hole formation is not 100% efficient in mass usage, stars are left over. This paper investigates the properties of such stars and proposes that their externally heated atmospheres become “bloated” due to radiative forces from trapped line radiation. Such stars would swell to many times their normal diameters and acquire densities, sizes, and mean column masses typical of QSO/AGN emission line clouds (ELCs).

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Janka, Hans-Thomas. "Neutron Star Formation and Birth Properties." Symposium - International Astronomical Union 218 (2004): 3–12. http://dx.doi.org/10.1017/s0074180900180465.

Повний текст джерела

Анотація:

Our current knowledge of neutron star formation, progenitors, and natal masses, spins, magnetic fields, and space velocities is briefly reviewed from a theorist's perspective. More observational information is badly needed to constrain theoretical possibilities.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Mallik, D. C. V. "Initial Masses." Symposium - International Astronomical Union 131 (1989): 493–504. http://dx.doi.org/10.1017/s0074180900139063.

Повний текст джерела

Анотація:

Planetary nebulae represent a transitory stage in the life of the majority of stars as they proceed towards the end of their nuclear evolution and descend to the domain of white dwarfs. The immediate precursors of the central stars are probably red giants which populate a part of the HR diagram far removed from the region inhabited by the central stars of well recognised nebulae. The problem of determining the initial masses is complicated by the widespread occurrence of massloss on the red giant branch. The total amount of mass lost by a star must depend upon a number of stellar parameters including the initial mass, but the exact nature of this dependence remains to be discovered and a unique relation between the final masses and initial main sequence masses is not yet available. Thus even though the mass distribution of the nuclei of planetary nebulae (NPN) has been derived in the last few years, it has not been possible to deduce from this an unambiguous initial mass distribution of the progenitors. Further, an observed sample always suffers from selection effects and, in the particular case of NPN mass distribution, this has led to irretrievable loss of information.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Liu, Tie, Yuefang Wu, and Huawei Zhang. "Molecular gas and triggered star formation surrounding Wolf-Rayet stars." Proceedings of the International Astronomical Union 8, S292 (August 2012): 48. http://dx.doi.org/10.1017/s174392131300029x.

Повний текст джерела

Анотація:

AbstractThe environments surrounding nine Wolf-Rayet stars were studied in molecular emission. Expanding shells were detected surrounding these WR stars (see left panels of Figure 1). The average masses and radii of the molecular cores surrounding these WR stars anti-correlate with the WR stellar wind velocities (middle panels of Figure 1), indicating the WR stars has great impact on their environments. The number density of Young Stellar Objects (YSOs) is enhanced in the molecular shells at ∼5 arcmin from the central WR star (lower-right panel of Figure 1). Through detailed studies of the molecular shells and YSOs, we find strong evidences of triggered star formation in the fragmented molecular shells (Liu et al. 2010).

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Beck, D. H. "Neutron decay, dark matter and neutron stars." EPJ Web of Conferences 219 (2019): 05006. http://dx.doi.org/10.1051/epjconf/201921905006.

Повний текст джерела

Анотація:

Following up on a suggestion that decay to a dark matter fermion might explain the 4σ discrepancy in the neutron lifetime, we consider the implications of such a fermion on neutron star structure. We find that including it reduces the maximum neutron star mass to well below the observed masses. In order to recover stars with the observed masses, the (repulsive) self-interactions of the dark fermion would have to be stronger than those of the nucleon-nucleon interaction.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Lattimer, James M. "Neutron Star Mass and Radius Measurements." Universe 5, no. 7 (June 28, 2019): 159. http://dx.doi.org/10.3390/universe5070159.

Повний текст джерела

Анотація:

Constraints on neutron star masses and radii now come from a variety of sources: theoretical and experimental nuclear physics, astrophysical observations including pulsar timing, thermal and bursting X-ray sources, and gravitational waves, and the assumptions inherent to general relativity and causality of the equation of state. These measurements and assumptions also result in restrictions on the dense matter equation of state. The two most important structural parameters of neutron stars are their typical radii, which impacts intermediate densities in the range of one to two times the nuclear saturation density, and the maximum mass, which impacts the densities beyond about three times the saturation density. Especially intriguing has been the multi-messenger event GW170817, the first observed binary neutron star merger, which provided direct estimates of both stellar masses and radii as well as an upper bound to the maximum mass.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Sakurai, Yuya, Naoki Yoshida, and Michiko S. Fujii. "Growth of intermediate mass black holes in first star clusters." Proceedings of the International Astronomical Union 14, S351 (May 2019): 220–23. http://dx.doi.org/10.1017/s1743921319007245.

Повний текст джерела

Анотація:

AbstractWe study runaway stellar collisions in primordial star clusters and formation of intermediate mass black holes (IMBHs). Using cosmological simulations, we identify eight atomic-cooling halos in which the star clusters form. We follow stellar and dark matter (DM) dynamics for 3Myr using hybrid N-body simulations. We find that the runaway stellar collisions occur in all star clusters and IMBHs with masses ∼400–1900M⊙ form. Performing additional N-body simulations, we explore evolutions of the IMBHs in the star clusters for 15 Myr. The IMBH masses grow via stellar tidal disruption events (TDEs) to ∼700–2500 M⊙. The TDE rates are ∼0.3–1.3 Myr−1. DM motions affect the star cluster evolutions and reduce the TDE rates. The IMBHs may subsequently grow to SMBHs by gas supply through galaxy mergers or large-scale gas inflows, or they may remain within or around the clusters.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Huber, H., M. K. Weigel, and F. Weber. "Compatibility of Neutron Star Masses and Hyperon Coupling Constants." Zeitschrift für Naturforschung A 54, no. 1 (January 1, 1999): 77–82. http://dx.doi.org/10.1515/zna-1999-0110.

Повний текст джерела

Анотація:

Abstract It is shown that the modern equations of state for neutron star matter based on microscopic calculations of symmetric and asymmetric nuclear matter are compatible with the lower bound on the maximum neutron-star mass for a certain range of hyperon coupling constants, which are constrained by the binding energies of hyperons in symmetric nuclear matter. The hyperons are included by means of the relativistic Hartree-or Hartree-Fock approximation. The obtained couplings are also in satisfactory agreement with hypernuclei data in the relativistic Hartree scheme. Within the relativistic Hartree-Fock approximation, hypernuclei have not been investigated so far.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Malla, Sai Prathyusha, Dennis Stello, Daniel Huber, Benjamin T. Montet, Timothy R. Bedding, Mads Fredslund Andersen, Frank Grundahl, et al. "Asteroseismic masses of four evolved planet-hosting stars using SONG and TESS: resolving the retired A-star mass controversy." Monthly Notices of the Royal Astronomical Society 496, no. 4 (June 22, 2020): 5423–35. http://dx.doi.org/10.1093/mnras/staa1793.

Повний текст джерела

Анотація:

ABSTRACT The study of planet occurrence as a function of stellar mass is important for a better understanding of planet formation. Estimating stellar mass, especially in the red giant regime, is difficult. In particular, stellar masses of a sample of evolved planet-hosting stars based on spectroscopy and grid-based modelling have been put to question over the past decade with claims they were overestimated. Although efforts have been made in the past to reconcile this dispute using asteroseismology, results were inconclusive. In an attempt to resolve this controversy, we study four more evolved planet-hosting stars in this paper using asteroseismology, and we revisit previous results to make an informed study of the whole ensemble in a self-consistent way. For the four new stars, we measure their masses by locating their characteristic oscillation frequency, νmax, from their radial velocity time series observed by SONG. For two stars, we are also able to measure the large frequency separation, Δν, helped by extended SONG single-site and dual-site observations and new Transiting Exoplanet Survey Satellite observations. We establish the robustness of the νmax-only-based results by determining the stellar mass from Δν, and from both Δν and νmax. We then compare the seismic masses of the full ensemble of 16 stars with the spectroscopic masses from three different literature sources. We find an offset between the seismic and spectroscopic mass scales that is mass dependent, suggesting that the previously claimed overestimation of spectroscopic masses only affects stars more massive than about 1.6 M⊙.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Kontizas, M., M. Chrysovergis, E. Kontizas, and D. Hadjidimitriou. "Tidal Radii and Masses of the Clusters in the LMC." Symposium - International Astronomical Union 116 (1986): 407–8. http://dx.doi.org/10.1017/s0074180900149307.

Повний текст джерела

Анотація:

Masses and tidal radii of star clusters in the LMC have been derived by means of star counts from U.K. Schmidt plates. Two groups of clusters according to their distance from the rotation centre of the LMC were measured. The tidal radii of the central clusters vary from 58 to 85 pc and those of the most distant clusters from 33 to 86 pc whereas masses were found to vary from 105 to 4×105M⊙ and from 104 to 2×105M⊙ respectively.

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Aoyama, Kohei, Tadayuki Kodama, Tomoko L. Suzuki, Ken-ichi Tadaki, Rhythm Shimakawa, Masao Hayashi, Yusei Koyama, and Jose Manuel Pérez-Martínez. "The Environmental Dependence of Gas Properties in Dense Cores of a Protocluster at z ∼ 2.5 Revealed with ALMA." Astrophysical Journal 924, no. 2 (January 1, 2022): 74. http://dx.doi.org/10.3847/1538-4357/ac34fa.

Повний текст джерела

Анотація:

Abstract In a protocluster USS1558-003 at z = 2.53, galaxies in the dense cores show systematically elevated star-forming activity compared to those in less dense regions. To understand its origin, we look into the gas properties of the galaxies in the dense cores by conducting deep 1.1 mm observations with the Atacama Large Millimeter/submillimeter Array. We detect interstellar dust continuum emission from 12 member galaxies and estimate their molecular gas masses. Comparing these gas masses with our previous measurements from the CO(3–2) line, we infer that the latter might be overestimated. We find that the gas to stellar mass ratios of the galaxies in the dense cores tend to be higher (at M * ∼ 1010 M ⊙ where we see the enhanced star-forming activity), suggesting that such large gas masses can sustain their high star-forming activity. However, if we compare the gas properties of these protocluster galaxies with the gas scaling relations constructed for field galaxies at a similar cosmic epoch, we find no significant environmental difference at the same stellar mass and star formation rate. Although both gas mass ratios and star-forming activity are enhanced in the majority of member galaxies, they appear to follow the same scaling relation as field galaxies. Our results are consistent with the scenario in which the cold gas is efficiently supplied to protocluster cores and to galaxies therein along surrounding filamentary structures, which leads to the high gas mass fractions and thus the elevated star formation activity, but without changing the star formation law.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Gilmore, G., and K. Arnaud. "Direct IR Determination of the Stellar Luminosity Function to 0.2 M⊙ in Elliptical Galaxies." Symposium - International Astronomical Union 127 (1987): 445–46. http://dx.doi.org/10.1017/s0074180900185663.

Повний текст джерела

Анотація:

SummaryWe present a determination of the stellar luminosity function in luminous elliptical galaxies which includes all stars more massive than 0.15 M⊙. This limit corresponds to masses beyond the maximum in the solar neighbourhood stellar mass function, and therefore includes effectively all the luminous mass. Galaxies with X-ray evidence for current massive star formation, also show no evidence for enhanced low mass star formation in their central regions. All elliptical galaxies studied to date have stellar luminosity functions for masses above 0.15 solar masses which do not differ significantly from that in the solar neighbourhood. Elliptical galaxies have stellar bolometric mass-to-light ratios of 2.5< M/L <5.0.

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Misiriotis, A., I. E. Papadakis, N. D. Kylafis, and J. Papamastorakis. "Dust masses and star formation in bright IRAS galaxies." Astronomy & Astrophysics 417, no. 1 (March 16, 2004): 39–50. http://dx.doi.org/10.1051/0004-6361:20035602.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Ми пропонуємо знижки на всі преміум-плани для авторів, чиї праці увійшли до тематичних добірок літератури. Зв'яжіться з нами, щоб отримати унікальний промокод!