Journal articles: 'Red clump'

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Girardi, Léo. "Red Clump Stars." Annual Review of Astronomy and Astrophysics 54, no. 1 (September 19, 2016): 95–133. http://dx.doi.org/10.1146/annurev-astro-081915-023354.

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Kamiński, T. "Massive dust clumps in the envelope of the red supergiant VY Canis Majoris." Astronomy & Astrophysics 627 (July 2019): A114. http://dx.doi.org/10.1051/0004-6361/201935408.

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The envelope of the red supergiant VY CMa has long been considered an extreme example of episodic mass loss that is possibly taking place in other cool and massive evolved stars. Recent (sub-)millimeter observations of the envelope revealed the presence of massive dusty clumps within 800 mas of the star and reinforce the picture of drastic mass-loss phenomena in VY CMa. We present new ALMA observations at an angular resolution of 0.1″ and at an unprecedented sensitivity that reveal further details about the dusty clumps. We resolve more discrete features and identify a submillimeter counterpart of a more distant Southwest (SW) Clump known from visual observations. The brightest clump, named C, is marginally resolved in the observations. Gas seen against the resolved continuum emission of clump C produces a molecular spectrum in absorption, in lines of mainly sulfur-bearing species. Except for SW Clump, no molecular emission is found to be associated with the dusty clumps and we propose that the dusty structures have an atypically low gas content. We attempt to reproduce the properties of the dusty clumps through 3D radiative transfer modeling. Although a clump configuration explaining the observations is found, it is not unique. A very high optical depth of all clumps to the stellar radiation makes the modeling very challenging, and requires an unrealistically high dust mass for one of the clumps. We suggest that the dusty features have substructures (e.g., porosity) that allow deeper penetration of stellar photons within the clumps than in a homogeneous configuration. A comparison of the estimated clump ages to variations in the stellar visual flux for over a century suggests that the mechanism responsible for their formation is not uniquely manifested by enhanced or strongly diminished visual light. The study demonstrates that the dusty mass-loss episodes of VY CMa are indeed unparalleled among all known non-explosive stars. The origin of these episodes remains an unsolved problem.

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Lucey, Madeline, Yuan-Sen Ting, Nesar S. Ramachandra, and Keith Hawkins. "From the inner to outer Milky Way: a photometric sample of 2.6 million red clump stars." Monthly Notices of the Royal Astronomical Society 495, no. 3 (January 2020): 3087–103. http://dx.doi.org/10.1093/mnras/staa1226.

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ABSTRACT Large pristine samples of red clump stars are highly sought after given that they are standard candles and give precise distances even at large distances. However, it is difficult to cleanly select red clumps stars because they can have the same Teff and log g as red giant branch stars. Recently, it was shown that the asteroseismic parameters, $\rm {\Delta }$P and $\rm {\Delta \nu }$, which are used to accurately select red clump stars, can be derived from spectra using the change in the surface carbon to nitrogen ratio ([C/N]) caused by mixing during the red giant branch. This change in [C/N] can also impact the spectral energy distribution. In this study, we predict the $\rm {\Delta }$P, $\rm {\Delta \nu }$, Teff, and log g using 2MASS, AllWISE, Gaia, and Pan-STARRS data in order to select a clean sample of red clump stars. We achieve a contamination rate of ∼20 per cent, equivalent to what is achieved when selecting from Teff and log g derived from low-resolution spectra. Finally, we present two red clump samples. One sample has a contamination rate of ∼20 per cent and ∼405 000 red clump stars. The other has a contamination of ∼33 per cent and ∼2.6 million red clump stars that includes ∼75 000 stars at distances >10 kpc. For |b| > 30 deg, we find ∼15 000 stars with contamination rate of ∼9 per cent. The scientific potential of this catalogue for studying the structure and formation history of the Galaxy is vast, given that it includes millions of precise distances to stars in the inner bulge and distant halo where astrometric distances are imprecise.

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López-Corredoira, M., Y. W. Lee, F. Garzón, and D. Lim. "Distribution of red clump stars does not support the X-shaped Galactic bulge." Astronomy & Astrophysics 627 (June 25, 2019): A3. http://dx.doi.org/10.1051/0004-6361/201935571.

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Context. Claims of an X-shaped Galactic bulge were based on the assumption of red clump stars as standard candles in some lines of sight crossing the off-plane bulge. However, some doubts have been cast on whether the two peaks in star counts along the line of sight really represent a double peak in the density distribution, or whether there is something wrong with the assumption of a unique constant absolute magnitude for all of these stars. Aims. With the advent of Gaia-DR2 parallaxes in combination with near-infrared VISTA-VVV data, we are able to check which of the hypotheses is correct. Methods. We calculated the median absolute magnitude MK corresponding to both peaks of putative red clumps in seven lines of sight with the lowest extinction in the interesting coordinates’ range. Results. The difference between the absolute magnitude of the bright and the faint peak is ΔMK ≈ 0.4. The selected stars in both peaks cannot be represented by the same red clump giants with constant MK ≈ −1.6. Conclusions. The hypothesis that the bulge contains an X-shape is based on the assumption that the faint and bright peaks of the density distribution towards the bulge are dominated by standard red clump stars. However, we show that both the faint and bright peaks cannot be dominated by standard red clump stars simultaneously.

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Ruiz-Dern, L., C. Babusiaux, F. Arenou, and C. Turon. "Characterisation of the Gaia Red Clump." EAS Publications Series 67-68 (2014): 395–96. http://dx.doi.org/10.1051/eas/1567084.

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Buldgen, Gaël, B. Rendle, T. Sonoi, G. R. Davies, A. Miglio, S. J. A. J. Salmon, D. R. Reese, et al. "Mean density inversions for red giants and red clump stars." Monthly Notices of the Royal Astronomical Society 482, no. 2 (August 27, 2018): 2305–19. http://dx.doi.org/10.1093/mnras/sty2346.

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Karaali, S., S. Bilir, and E. Yaz Gökçe. "Absolute magnitude calibration for red clump stars." Astrophysics and Space Science 346, no. 1 (April 20, 2013): 89–104. http://dx.doi.org/10.1007/s10509-013-1449-7.

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Garnavich, P. M., and K. Stanek. "Red Clump Stars – Further Improved Distance Indicator." Highlights of Astronomy 12 (2002): 688. http://dx.doi.org/10.1017/s1539299600014672.

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AbstractThe ideal distance indicator would be a standard candle abundant enough to provide many examples within reach of parallax measurements and sufficiently bright to be seen out to Local Group galaxies. The red clump stars closely match this description. These are the metal rich equivalent of the better known horizontal branch stars, and their brightness dispersion is only 0.2 mag (one sigma) in the Solar neighborhood. Using Hipparcos to calibrate a large, local sample, the red clump method has been used to measure accurate distances to the Galactic center (Paczyński & Stanek 1998), M31 (Stanek & Garnavich 1998), LMC (Udalski et al. 1998; Stanek et al. 1998; Udalski 1999) and some clusters in our Galaxy (e.g. 47Tuc: Kaluzny et al. 1998). As with all the distance indicators, the main worry lies in the possible systematics of the method, in particular, the brightness dependence on the stellar metallicity and age. These dependences have come under close scrutiny and, indeed, the population effects on the red clump brightness appear small and calibratable. Perhaps the most controversial result from the red clump method is the estimation of a “short” distance to the Large Magellanic Cloud (Udalski et al. 1998; Stanek, Zaritsky & Harris 1998; Udalski 2000). This distance to the LMC is shorter by 12% than the “standard” value, and has very important implications for the Cepheid distance scale and the determination of the Hubble constant.

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Abedigamba, O. P., L. A. Balona, and T. R. Medupe. "Red Clump stars inKepleropen cluster NGC 6819." EPJ Web of Conferences 101 (2015): 06001. http://dx.doi.org/10.1051/epjconf/201510106001.

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Liu, Y. J., G. Zhao, J. R. Shi, G. Pietrzyński, and W. Gieren. "The abundances of nearby red clump giants*." Monthly Notices of the Royal Astronomical Society 382, no. 2 (November 7, 2007): 553–66. http://dx.doi.org/10.1111/j.1365-2966.2007.11852.x.

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Bilir, S., Ö. Önal, S. Karaali, A. Cabrera-Lavers, and H. Çakmak. "Luminosity–colour relations for red clump stars." Astrophysics and Space Science 344, no. 2 (January 5, 2013): 417–27. http://dx.doi.org/10.1007/s10509-012-1342-9.

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Salaris, Maurizio. "Evolutionary properties of stellar standard candles: Red clump, AGB clump and white dwarfs." Proceedings of the International Astronomical Union 8, S289 (August 2012): 145–52. http://dx.doi.org/10.1017/s1743921312021278.

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AbstractThe location of the white dwarf cooling sequence in the colour–magnitude diagram of simple stellar populations, the magnitude of the red clump and the magnitude of the asymptotic giant branch clump are three stellar distance indicators based on advanced evolutionary phases of low-mass stars. With the present observational capabilities, they can be applied to reach distances ranging from the Galactic disk and halo populations, to galaxies within the Local Group. Techniques devised to exploit these distance indicators are presented, together with a discussion of their calibration and the main sources of systematic errors. A first semi-empirical calibration of the asymptotic giant branch absolute magnitude in both the I and K bands is also derived.

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Ruiz-Dern, L., C. Babusiaux, F. Arenou, C. Turon, and R. Lallement. "Empirical photometric calibration of the Gaia red clump: Colours, effective temperature, and absolute magnitude." Astronomy & Astrophysics 609 (January 2018): A116. http://dx.doi.org/10.1051/0004-6361/201731572.

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Context. Gaia Data Release 1 allows the recalibration of standard candles such as the red clump stars. To use those stars, they first need to be accurately characterised. In particular, colours are needed to derive interstellar extinction. As no filter is available for the first Gaia data release and to avoid the atmosphere model mismatch, an empirical calibration is unavoidable. Aims. The purpose of this work is to provide the first complete and robust photometric empirical calibration of the Gaia red clump stars of the solar neighbourhood through colour–colour, effective temperature–colour, and absolute magnitude–colour relations from the Gaia, Johnson, 2MASS, Hipparcos, Tycho-2, APASS-SLOAN, and WISE photometric systems, and the APOGEE DR13 spectroscopic temperatures. Methods. We used a 3D extinction map to select low reddening red giants. To calibrate the colour–colour and the effective temperature–colour relations, we developed a MCMC method that accounts for all variable uncertainties and selects the best model for each photometric relation. We estimated the red clump absolute magnitude through the mode of a kernel-based distribution function. Results. We provide 20 colour versus G−Ks relations and the first Teff versus G−Ks calibration. We obtained the red clump absolute magnitudes for 15 photometric bands with, in particular, MKs = (−1.606 ± 0.009) and MG = (0.495 ± 0.009) + (1.121 ± 0.128)(G−Ks−2.1). We present a dereddened Gaia-TGAS HR diagram and use the calibrations to compare its red clump and its red giant branch bump with Padova isochrones.

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Masseron, T., and K. Hawkins. "The spectroscopic indistinguishability of red giant branch and red clump stars." Astronomy & Astrophysics 597 (December 22, 2016): L3. http://dx.doi.org/10.1051/0004-6361/201629938.

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Mallick, Anohita, Bacham E. Reddy, and C. Muthumariappan. "Probing infrared excess connection with Li enhancement among red clump giants." Monthly Notices of the Royal Astronomical Society 511, no. 3 (January 29, 2022): 3741–50. http://dx.doi.org/10.1093/mnras/stac224.

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ABSTRACT We have performed a search among low-mass red giants for finding evidence for merger scenario for triggering He-flash and subsequent Li enhancement. We chose a sample of red giants from GALAH survey with well-measured Li abundances, and near- and mid-IR fluxes from 2MASS and WISE surveys, respectively. The sample contains 418 cool red clump giants and 359 upper red giant branch (RGB) giants. Most of the giants and majority of super Li-rich giants show no IR excess. Only five red clump giants and one RGB giant show IR excess. Notably, of the five red clump giants with IR excess, three are super Li-rich (A(Li) ≥ 3.2 dex) and two are Li-rich (A(Li) ≥ 1.0 dex). Results suggest that Li enhancement among red clump giants may be due to two channels: one resulting from in situ He-flash in single-star evolution and the other due to He-flash triggered by events like merger of He-white dwarfs with giants’ He-inert core on RGB. In the latter case, IR excess, as a result of mass-loss, is expected from merger events. We have modelled IR excess in all six giants using dusty code and derived dust parameters. The estimated kinematic ages and time-scales of dust envelopes of the super Li-rich phase suggest that Li enhancement took place very recently. Further, the analysis shows a significantly higher proportion (four out of five red clump giants) of rapid rotators (vsini ≥ 8 km s−1) among Li-rich giants with IR excess compared to Li-normal and Li-rich giants with no IR excess.

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Stanek, K. Z., M. Mateo, A. Udalski, M. Szymański, J. Kałuzny, M. Kubiak, and W. Krzemiński. "Modelling the Galactic Bar using Red Clump Stars." International Astronomical Union Colloquium 157 (1996): 545–48. http://dx.doi.org/10.1017/s0252921100050405.

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AbstractThe color-magnitude diagrams of ~ 1 × 106 stars obtained for 19 fields towards the Galactic bulge with the OGLE project reveal a well-defined population of bulge red clump stars. We found that the distributions of the extinction-adjusted apparent magnitudes of red clump stars in fields lying at ι = ±5° in galactic longitude differ by ∼ 0.4 mag. A plausible explanation of this observed difference in the luminosity distribution is that the Galactic bulge is a triaxial structure, or a bar, which is inclined to the line of sight by no more than 45°. The part of the bar at the positive galactic longitude is closer to us. Work is now under way to model the Galactic bar by fitting the observed luminosity functions in the red clump region for various fields. Preliminary results indicate that the angle of the inclination of the bar to the line of sight can be as small as ∼ 20°. Gravitational microlensing can provide us with additional constraints on the structure of the Galactic bar.

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Ruiz-Dern, L., C. Babusiaux, F. Arenou, C. Danielski, C. Turon, and P. Sartoretti. "Calibration and characterisation of the Gaia Red Clump." Proceedings of the International Astronomical Union 12, S330 (April 2017): 313–16. http://dx.doi.org/10.1017/s1743921317006147.

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AbstractWe present new empirical Colour-Colour and Effective Temperature-Colour Gaia Red Clump calibrations. The selected sample takes into account high photometric quality, good spectrometric metallicity, homogeneous effective temperatures and low interstellar extinctions. From those calibrations we developed a method to derive the absolute magnitude, temperature and extinction of the Gaia RC. We tested our colour and extinction estimates on stars with measured spectroscopic effective temperatures and Diffuse Interstellar Band (DIB) constraints. Within the Gaia Validation team these calibrations are also being used, together with asteroseismic constraints, to check the parallax zero-point with Red Clump stars.

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Liu, Chao, Hai-Jun Tian, and Jun-Chen Wan. "The age-kinematical features in the Milky Way outer disk." Proceedings of the International Astronomical Union 11, S321 (March 2016): 6–9. http://dx.doi.org/10.1017/s1743921316011029.

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AbstractWe derive the mean velocity components at various Galactocentric radii from 8 to 14 kpc using about 40,000 red clump stars observed in the LAMOST survey. We find that the vertical bulk motion for younger red clump stars are significantly larger than that for the older red clump stars. This is likely the kinematical feature of the Galactic warp around its line-of-node, which is located close to the Galactic anti-center region. It is evident that the warp are mainly contributed by the younger stars rather than the older stars. The age variation in the vertical kinematics favors a formation scenario where the Galactic warp is originated from infalling misaligned gas.

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Cannon, E., M. Montargès, A. de Koter, L. Decin, M. Min, E. Lagadec, P. Kervella, J. O. Sundqvist, and H. Sana. "The inner circumstellar dust of the red supergiant Antares as seen with VLT/SPHERE/ZIMPOL." Monthly Notices of the Royal Astronomical Society 502, no. 1 (January 9, 2021): 369–82. http://dx.doi.org/10.1093/mnras/stab018.

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ABSTRACT The processes by which red supergiants lose mass are not fully understood thus-far and their mass-loss rates lack theoretical constraints. The ambient surroundings of the nearby M0.5 Iab star Antares offer an ideal environment to obtain detailed empirical information on the outflow properties at its onset, and hence indirectly, on the mode(s) of mass-loss. We present and analyse optical VLT/SPHERE/ZIMPOL polarimetric imaging with angular resolution down to 23 milliarcsec, sufficient to spatially resolve both the stellar disc and its direct surroundings. We detect a conspicuous feature in polarized intensity that we identify as a clump containing dust, which we characterize through 3D radiative transfer modelling. The clump is positioned behind the plane of the sky, therefore has been released from the backside of the star, and its inner edge is only 0.3 stellar radii above the surface. The current dust mass in the clump is $1.3^{+0.2}_{-1.0} \times 10^{-8} \, \mathrm{M}_{\odot }$, though its proximity to the star implies that dust nucleation is probably still ongoing. The ejection of clumps of gas and dust makes a non-negligible contribution to the total mass lost from the star that could possibly be linked to localized surface activity such as convective motions or non-radial pulsations.

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Rybka, S. P. "Catalog of red clump candidates in Tycho-2." Kinematics and Physics of Celestial Bodies 23, no. 2 (April 2007): 70–72. http://dx.doi.org/10.3103/s0884591307020043.

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Rybka, S. P., and A. I. Yatsenko. "Candidate red clump giants in the PPMX catalogue." Kinematics and Physics of Celestial Bodies 27, no. 2 (April 2011): 79–85. http://dx.doi.org/10.3103/s0884591311020073.

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Zhao, Gang, Hong-mei Qiu, and Hua-wei Zhang. "Abundance of α-elements in red clump giants." Chinese Astronomy and Astrophysics 25, no. 1 (January 2001): 59–64. http://dx.doi.org/10.1016/s0275-1062(01)00044-3.

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Liu, Chao, Glenn van de Ven, Min Fang, Yue Wu, Kenneth Carrell, and Xiangxiang Xue. "The Galactic rotation curve from red clump stars." Proceedings of the International Astronomical Union 9, S298 (May 2013): 424. http://dx.doi.org/10.1017/s174392131300690x.

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AbstractWe use line-of-sight velocities of more than 4000 red clump stars observed from MMT/Hectospec to derive the Galactic rotation curve between 8 and 13 kpc in Galactocentric radius to better than 10 km s−1. A three-component (bulge+disk+halo) with an additional massive ring of 1.66×1010 M⊙ at about 11.6 kpc provides an excellent fit with the observation.

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Stanek, K. Z., A. Udalski, M. Szymański, J. Kałużny, Z. M. Kubiak, M. Mateo, and W. Krzemiński. "Modeling the Galactic Bar Using Red Clump Giants." Astrophysical Journal 477, no. 1 (March 1997): 163–75. http://dx.doi.org/10.1086/303702.

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Alves, David R. "K‐Band Calibration of the Red Clump Luminosity." Astrophysical Journal 539, no. 2 (August 20, 2000): 732–41. http://dx.doi.org/10.1086/309278.

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Salomon, Jean-Baptiste, Olivier Bienaymé, Céline Reylé, Annie C. Robin, and Benoit Famaey. "Kinematics and dynamics of Gaia red clump stars." Astronomy & Astrophysics 643 (November 2020): A75. http://dx.doi.org/10.1051/0004-6361/202038535.

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In this study, we analyse the kinematics and dynamics of a homogeneous sample of red clump stars, selected from the second Gaia data release catalogue in the direction of the Galactic poles, at five different positions in the plane. The level of completeness of the sample at heights between 0.6 and 3.5 kpc was asserted through a comparison with the 2 Micron All Sky Survey catalogue. We show that both the density distribution and velocity dispersion are significantly more perturbed in the north than in the south in all analysed regions of our Galactic neighbourhoods. We provide a detailed assessment of these north-south asymmetries at large heights, which can provide useful constraints for models of the interaction of the Galactic disc with external perturbers. We proceeded to evaluate how such asymmetries could affect determinations of the dynamical matter density under equilibrium assumptions. We find that a Jeans analysis delivers relatively similar vertical forces and integrated dynamical surface densities at large heights above the plane in both hemispheres. At these heights, the densities of stars and gas are very low and the surface density is largely dominated by dark matter (DM), which allows us to estimate, separately in the north and in the south, the local dark matter density derived under equilibrium assumptions. In the presence of vertical perturbations, such values should be considered as an upper limit. This Jeans analysis yields values of the local dark matter density above 2 kpc, namely, ρDM ∼ 0.013 M⊙ pc−3 (∼0.509 GeV cm−3) in the perturbed northern hemisphere and ρDM ∼ 0.010 M⊙ pc−3 (∼0.374 GeV cm−3) in the much less perturbed south. As a comparison, we determine the local dark matter density by fitting a global phase-space distribution to the data. We end up with a value in the range of ρDM ∼ 0.011−0.014 M⊙ pc−3, which is in global agreement with the Jeans analysis. These results call for the further development of non-equilibrium methods with the aim of obtaining a more precise estimate for the dynamical matter density in the Galactic disc.

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Gontcharov, G. A. "Red giant clump in the Tycho-2 catalogue." Astronomy Letters 34, no. 11 (November 2008): 785–96. http://dx.doi.org/10.1134/s1063773708110078.

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Bobylev, V. V., A. S. Stepanishchev, A. T. Bajkova, and G. A. Gontcharov. "Kinematics of Tycho-2 red giant clump stars." Astronomy Letters 35, no. 12 (December 2009): 836–49. http://dx.doi.org/10.1134/s1063773709120044.

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Seidel, E., P. Demarque, and D. Weinberg. "The evolution of red clump stars - Theoretical sequences." Astrophysical Journal Supplement Series 63 (April 1987): 917. http://dx.doi.org/10.1086/191186.

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Davies, Guy R., Mikkel N. Lund, Andrea Miglio, Yvonne Elsworth, James S. Kuszlewicz, Thomas S. H. North, Ben Rendle, et al. "Using red clump stars to correct theGaiaDR1 parallaxes." Astronomy & Astrophysics 598 (January 26, 2017): L4. http://dx.doi.org/10.1051/0004-6361/201630066.

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Cabrera-Lavers, A., P. L. Hammersley, C. González-Fernández, M. López-Corredoira, F. Garzón, and T. J. Mahoney. "Tracing the long bar with red-clump giants." Astronomy & Astrophysics 465, no. 3 (January 29, 2007): 825–38. http://dx.doi.org/10.1051/0004-6361:20066185.

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Carrell, Kenneth, Ronald Wilhelm, and YuQin Chen. "RED CLUMP STARS IN THE SAGITTARIUS TIDAL STREAMS." Astronomical Journal 144, no. 1 (June 8, 2012): 18. http://dx.doi.org/10.1088/0004-6256/144/1/18.

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Girardi, Léo. "Theoretical Expectations for Clump Red Giants as Distance Indicators." Highlights of Astronomy 12 (2002): 689–93. http://dx.doi.org/10.1017/s1539299600014684.

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AbstractVariations of ~ 0.4 mag are expected in theI-band absolute magnitude of red clump giants,, as a function of both stellar age and metallicity. This is the case regardless of some potential theoretical uncertainties. The quite large differences in mean ages and metallicities of clump stars among galaxies result in systematic changes (of up to ~ 0.4 mag) in their. These numbers also indicate a distance to the LMC that is not necessarily “short”.

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Kusnarta, I. G. M., D. Rahmadhanti, N. W. D. Dulur, and W. Wangiyana. "Soil chemical characteristics and yield of red rice under aerobic irrigation system as affected by intercropping with peanut and application of organic wastes on permanent raised-beds." IOP Conference Series: Earth and Environmental Science 913, no. 1 (November 1, 2021): 012002. http://dx.doi.org/10.1088/1755-1315/913/1/012002.

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Abstract Intercropping with peanuts was reported to increase yield of cereal crops. The objective of this study was to examine the effect of peanut-intercropping and organic waste application on some soil chemical characteristics and red-rice yield under aerobic irrigation systems. The experiment was conducted from May to August 2020 in West Lombok (Indonesia), under Split Plot design, testing two factors, namely intercropping (T1=monocropped rice; T2=rice+peanut intercropping) in the main plots, and organic waste application (L0=without organic waste, L1=application of rice husk, L2=rice husk ash, L3=rice husk ash and cattle manure) in the subplots. Results showed that intercropping did not affect soil chemical properties but it significantly increased number of panicles and filled-grains, 100 grain weight, and grain yield of red rice per clump (31.27 g/clump under monocrop and 41.50 g/clump under intercropping with peanut). In contrast, organic waste application significantly influenced soil chemical characteristics and red-rice yield (the highest yield of 43.52 g/clump under L3). The significant interaction between factors on 100 grain weight indicated that the highest weight (2.89 g) was on intercropped red-rice under L3 treatment and the lowest one (2.18 g) was on monocropped red-rice under L2 treatment.

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Bersier, D. "The Distance to the Fornax Dwarf Galaxy Using Red Clump Stars and the Discrepancy between Red Clump and Tip of the Red Giant Branch Distances." Astrophysical Journal 543, no. 1 (November 1, 2000): L23—L26. http://dx.doi.org/10.1086/318170.

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Lim, D., A. J. Koch-Hansen, C. Chung, C. I. Johnson, A. Kunder, I. T. Simion, R. M. Rich, et al. "Blanco DECam Bulge Survey (BDBS)." Astronomy & Astrophysics 647 (March 2021): A34. http://dx.doi.org/10.1051/0004-6361/202039955.

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Red clump (RC) stars are one of the best stellar tracers of the structure of the Milky Way (MW) bulge. Here we report a new view of the double RC through luminosity and color distributions of RC stars in nine bulge fields (l = 0.0°, ±4.5°; b = −6.0°, −7.5°, −9.0°) from the Blanco DECam Bulge Survey (BDBS), which covers near-ultraviolet to near-infrared bandpasses. The bright and faint RCs show contrasting distributions in (u − g)0 and (u − i)0 colors but similar distributions in (J − Ks)0 with a variation depending on the Galactic longitude, where the bright RC is typically redder than the faint RC. In particular, the RC stars are clearly divided into the bluer and redder populations when using the (u − g)0 color ((u − g)0 < 2.5 for the bluer RC; (u − g)0 ≥ 2.5 for the redder RC). The bluer stars show a single clump on the faint RC regime, whereas the redder stars form double clumps on both the bright and faint RCs. The bright clump of the redder stars is dominant in the positive longitude fields, while the faint clump of those red stars is significant at negative longitudes. We also confirm that the bluer and redder stars have different peak metallicity through comparison with spectroscopy (Δ[Fe/H] ∼ 0.45 dex). Therefore, our results support a scenario whereby the MW bulge is composed of a spheroid of metal-poor stars and a boxy/peanut shape (X-shape) predominantly made up of metal-rich stars.

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Chan, Victor C., and Jo Bovy. "The Gaia DR2 parallax zero-point: hierarchical modelling of red clump stars." Monthly Notices of the Royal Astronomical Society 493, no. 3 (February 27, 2020): 4367–81. http://dx.doi.org/10.1093/mnras/staa571.

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ABSTRACT The systematic offset of Gaia parallaxes has been widely reported with Gaia’s second data release, and it is expected to persist in future Gaia data. In order to use Gaia parallaxes to infer distances to high precision, we develop a hierarchical probabilistic model to determine the Gaia parallax zero-point offset along with the calibration of an empirical model for luminosity of red clump stars by combining astrometric and photometric measurements. Using a cross-matched sample of red clump stars from the Apache Point Observatory Galactic Evolution Experiment and Gaia Data Release 2 (DR2), we report the parallax zero-point offset in DR2 to be $\varpi _0 = -48 \pm 1\,\mu \text{as}$. We infer the red clump absolute magnitude to be −1.622 ± 0.004 in Ks, 0.435 ± 0.004 in G, −1.019 ± 0.004 in J, and −1.516 ± 0.004 in H. The intrinsic scatter of the red clump is ∼0.09 mag in J, H, and Ks, or ∼ 0.12 mag in G. We tailor our models to accommodate more complex analyses such as investigating the variations of the parallax zero-point with each source’s observed magnitude, observed colour, and sky position. In particular, we find fluctuations of the zero-point across the sky to be of order or less than a few 10s of $\mu \text{as}$.

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Mori, Kanji, Motohiko Kusakabe, A. Baha Balantekin, Toshitaka Kajino, and Michael A. Famiano. "Enhancement of Lithium in Red Clump Stars by Neutrino Magnetic Moments." EPJ Web of Conferences 260 (2022): 11016. http://dx.doi.org/10.1051/epjconf/202226011016.

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A recent spectroscopic survey has shown that the lithium abundances in low-mass red-clump stars are higher than theoretical prediction. Motivated by their finding, we implemented effects of additional energy losses induced by neutrino magnetic moments on stellar evolution models. It is found that the lithium abundances in red giants increase because the finite magnetic moments of neutrinos enhance the efficiency of deep mixing and 7Be is conveyed from the hydrogen burning shell to the convective envelope. The results motivate further studies on the effects of non-standard energy losses on the surface compositions of low-mass red giants and red-clump stars.

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Rybka, S. P., and A. I. Yatsenko. "Identification of red clump giants by 2MASS photometric data." Kinematics and Physics of Celestial Bodies 25, no. 4 (August 2009): 220–25. http://dx.doi.org/10.3103/s0884591309040084.

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Shan, S. S., H. Zhu, W. W. Tian, M. F. Zhang, H. Y. Zhang, D. Wu, and A. Y. Yang. "Distances of Galactic Supernova Remnants Using Red Clump Stars." Astrophysical Journal Supplement Series 238, no. 2 (October 23, 2018): 35. http://dx.doi.org/10.3847/1538-4365/aae07a.

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López-Corredoira, M., A. Cabrera-Lavers, P. L. Hammersley, F. Garzón, T. J. Mahoney, and C. González-Fernández. "Red clump giant stars as tracers of Galactic structure." Proceedings of the International Astronomical Union 5, H15 (November 2009): 811. http://dx.doi.org/10.1017/s1743921310011890.

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AbstractBy isolating the red clump giant population in the color-magnitude diagrams and inverting their star counts, we can obtain directly the density distribution of the old stellar population along the line of sight. We have applied this method to several near infrared surveys and obtained information on the disc, bulge and long bar. The disc is well fitted by an exponential distribution in both the galactocentric distance and height, flared and warped in the outer parts, and with a deficit of stars in the inner in-plane regions. The long bar occupies these in-plane regions within R < 3.9 kpc, with approximate dimensions of 7.8 kpc × 1.2 kpc × 0.2 kpc and a position angle of 40-45 deg. The bulge is a triaxial structure, possibly boxy, thicker and shorter than the long bar and with position angle of 10-30 deg.

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Bilir, S., T. Ak, S. Ak, T. Yontan, and Z. F. Bostancı. "A new absolute magnitude calibration for red clump stars." New Astronomy 23-24 (October 2013): 88–97. http://dx.doi.org/10.1016/j.newast.2013.03.006.

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Mao, S., and B. Paczynski. "Constraining the Galactic bar parameters with red clump giants." Monthly Notices of the Royal Astronomical Society 337, no. 3 (December 11, 2002): 895–900. http://dx.doi.org/10.1046/j.1365-8711.2002.05951.x.

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Correnti, M., M. Bellazzini, and F. R. Ferraro. "Red Clump stars in the Boötes III stellar system." Monthly Notices of the Royal Astronomical Society: Letters 397, no. 1 (July 21, 2009): L26—L30. http://dx.doi.org/10.1111/j.1745-3933.2009.00677.x.

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López-Corredoira, M., H. Abedi, F. Garzón, and F. Figueras. "Vertical velocities from proper motions of red clump giants." Astronomy & Astrophysics 572 (December 2014): A101. http://dx.doi.org/10.1051/0004-6361/201424573.

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Tautvaišienė, G., E. Puzeras, Y. Chorniy, G. Barisevičius, and I. Ilyin. "CNO abundance pattern in the red clump stars of the Milky Way." Proceedings of the International Astronomical Union 5, S262 (August 2009): 434–35. http://dx.doi.org/10.1017/s1743921310003583.

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AbstractHipparcos orbiting observatory has revealed a large number of helium-core- burning “clump” stars of the Galactic field. These low-mass stars exhibit signatures of extra-mixing processes that require modeling beyond the standard stellar theory. In this contribution we overview available results of 12C, 13C, N and O abundances obtained by high-resolution spectra for clump stars and discuss them in the light of current predictions of stellar evolution models.

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Girardi, Léo, Stefano Rubele, and Leandro Kerber. "Star clusters with dual red clumps." Proceedings of the International Astronomical Union 5, S266 (August 2009): 320–25. http://dx.doi.org/10.1017/s1743921309991207.

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AbstractA few star clusters in the Magellanic Clouds exhibit composite structures in the red-clump region of their colour–magnitude diagrams. The most striking case is NGC 419 in the Small Magellanic Cloud (SMC), where the red clump is composed of a main blob as well as a distinct secondary feature. This structure is demonstrated to be real and corresponds to the simultaneous presence of stars which passed through electron degeneracy after central-hydrogen exhaustion and those that did not. This rare occurrence in a single cluster allows us to set stringent constraints on its age and on the efficiency of convective-core overshooting during main-sequence evolution. We present a more detailed analysis of NGC 419, together with a first look at other populous Large Magellanic Cloud clusters which are apparently in the same phase: NGC 1751, NGC 1783, NGC 1806, NGC 1846, NGC 1852 and NGC 1917. We also compare these Magellanic Cloud cases with their Galactic counterparts, NGC 752 and NGC 7789. We emphasise the extraordinary potential of these clusters as absolute calibration marks on the age scale of stellar populations.

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Lamson, Neil I. "Precommercial Thinning and Pruning of Appalachian Stump Sprouts—10-Year Results." Southern Journal of Applied Forestry 12, no. 1 (February 1, 1988): 23–27. http://dx.doi.org/10.1093/sjaf/12.1.23.

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Abstract In northern West Virginia, 7-year-old American basswood (Tilia americana L.) and 12-year-old red maple (Acer rubrum L.), black cherry (Prunus serotina Ehrh.), and northern red oak (Quercus rubra L.) stump sprout clumps received one of four treatments: unthinned control; thinned to the best one or two codominant sprouts per clump; branch pruned up to 75% of total height; or thinned plus pruned. Analysis of 10-year growth data showed that height growth was not affected by any of the treatments. For all species, pruning slightly increased the length of clear stem and decreased periodic diameter growth. Thinning increased survival of basswood, red oak, and red maple crop stems. Thinning increased the 10-year diameter growth by 0.1 to 0.8 in. Recommendations for thinning 10- to 20-year-old sprout clumps are presented. Pruning is not recommended. In order to maintain maximum diameter growth, thinning individual sprout clumps should be followed by stand crop tree release in about 10 years. South. J. Appl. For. 12(1):23-27.

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Lidar, Seprita, and Indra Purnama. "Growth of celery (Apium graveolens L.) in the red-yellow podzolic soils as inoculated by earthworms Pontoscolex corethrurus." Jurnal Ilmiah Pertanian 17, no. 2 (February 26, 2021): 67–73. http://dx.doi.org/10.31849/jip.v17i2.5742.

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In this study, the inoculation effect of earthworms Pontoscolex corethrurus on celery growth (Apium graveolens L.) has been carried out in red-yellow podzolic (RYP) soils. The research studied in a pot experiment using a completely randomized design (CRD) with 6 (six) treatments and 3 (three) replications. One-pot consists of 4 (four) plants. The treatments carried out were as follows: I0 (without inoculum of earthworm), I1 (inoculum of 5 earthworms pot-1), I2 (inoculum of 10 earthworms pot-1), I3 (inoculum of 15 earthworms pot-1), I4 (inoculum of 10 earthworms pot-1) and I5 (inoculum of 25 earthworms pot-1). Observation parameters were the number of tillers clumps-1, fresh biomass clumps-1 (g clump-1), and root volume (mL). The observations were statistically analyzed using variance (one-way ANOVA) and followed by the Duncan Multiple Range Test (DMRT) with a level of 5%. Treatment I5 gave the best results on celery crop in all parameters, i.e., 20.33 tillers per hill; fresh biomass per clump 113.93 g; and a root volume of 10 mL. The results showed that earthworms' inoculation into RYP soils significantly affected all parameters. There was also an increase in pH in each treatment that was inoculated with earthworms.

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Popowski, Piotr. "The Distance to the Large Magellanic Cloud." International Astronomical Union Colloquium 176 (2000): 203–7. http://dx.doi.org/10.1017/s0252921100057547.

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AbstractI demonstrate that the two unexpected results in the local Universe: anomalous intrinsic (V – I)0 colors of RR Lyrae stars and clump giants in the Galactic center, and very short distances to Magellanic Clouds inferred from clump giants, can be at least partially resolved with a modified coefficient of selective extinction AV/E(V – I). With this modification, I find a new clump-giant distance modulus to the Large Magellanic Cloud, μLMC = 18.27 ± 0.07, which is 0.09 larger than the Udalski (1998b) result. When distance estimates from the red clump, RR Lyrae stars and the eclipsing binary HV2274 are combined, one obtains μLMC = 18.31 ± 0.04 (internal).

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Journal articles on the topic 'Red clump'

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