scholarly journals Extended star-forming regions within galaxies in a dense proto-cluster core at z = 2.53†

2019 ◽  
Vol 71 (4) ◽  
Author(s):  
Tomoko L Suzuki ◽  
Yosuke Minowa ◽  
Yusei Koyama ◽  
Tadayuki Kodama ◽  
Masao Hayashi ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Structural Evolution ◽  
Cluster Core ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
Star Formation Activity ◽  
Radial Profiles ◽  
Structural Growth ◽  
The One

Abstract At z ∼ 2, star formation activity is thought to be high even in high-density environments such as galaxy clusters and proto-clusters. One of the critical but outstanding issues is if the structural growth of star-forming galaxies can differ depending on their surrounding environments. In order to investigate how galaxies grow their structures and what physical processes are involved in the evolution of galaxies, one requires spatially resolved images of not only stellar components but also star-forming regions within galaxies. We conducted (Adaptive Optics) AO-assisted imaging observations for star-forming galaxies in a dense proto-cluster core at z = 2.53 with IRCS and AO188 mounted on the Subaru Telescope. A combination of AO and narrow-band filters allows us to obtain resolved maps of Hα-emitting regions with an angular resolution of ${0{^{\prime\prime}_{.}}1}$–${0{^{\prime\prime}_{.}}2}$, which corresponds to ∼1 kpc at z ∼ 2.5. Based on stacking analyses, we compare radial profiles of star-forming regions and stellar components and find that the star-forming region of a sub-sample with log (M*/$M_\odot$) ∼ 10–11 is more extended than the stellar component, indicating the inside-out growth of the structure. This trend is similar to the one for star-forming galaxies in general fields at z = 2–2.5 obtained with the same observational technique. Our results suggest that the structural evolution of star-forming galaxies at z = 2–2.5 is mainly driven by internal secular processes irrespective of surrounding environments.

scholarly journals The Spatially-Resolved Star Formation History of the M31 Disk from Resolved Stellar Populations

2014 ◽  
Vol 10 (S309) ◽  
pp. 57-60
Author(s):  
Alexia R. Lewis ◽  
Julianne J. Dalcanton ◽  
Andrew E. Dolphin ◽  
Daniel R. Weisz ◽  
Benjamin F. Williams ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Populations ◽  
Star Formation History ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
Star Formation Activity ◽  
Individual Star ◽  
Star Formation Histories ◽  
Optical Color

AbstractThe Panchromatic Hubble Andromeda Treasury (PHAT) is an HST multi-cycle treasury program that has mapped the resolved stellar populations of ∼1/3 of the disk of M31 from the UV through the near-IR. This data provides color and luminosity information for more than 150 million stars. Using stellar evolution models, we model the optical color-magnitude diagram to derive spatially-resolved recent star formation histories (SFHs) over large areas of M31 with 100 pc resolution. These include individual star-forming regions as well as quiescent portions of the disk. With these gridded SFHs, we create movies of star formation activity to study the evolution of individual star-forming events across the disk. We analyze the structure of star formation and examine the relation between star formation and gas throughout the disk and particularly in the 10-kpc star-forming ring. We find that the ring has been continuously forming stars for at least 500 Myr. As the only large disk galaxy that is close enough to obtain the photometry for this type of spatially-resolved SFH mapping, M31 plays an important role in our understanding of the evolution of an L* galaxy.

scholarly journals Using stellar population studies to determine the progenitors of GRBs and SNe

2009 ◽  
Vol 5 (S262) ◽  
pp. 436-437
Author(s):  
Christina C. Thöne ◽  
Lise Christensen ◽  
Johan P. U. Fynbo
Keyword(s):  
Emission Line ◽  
Stellar Population ◽  
Population Studies ◽  
Population Models ◽  
Host Galaxy ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions

AbstractWe present spatially resolved emission line studies of three nearby GRB and SN hosts with longslit and/or IFU observations. We compare the environment of the GRBs/SNe with those of other star-forming regions in the host galaxy and try to get informations on the progenitor from stellar population models and metallicities.

Deep Near-Infrared Surveys and Young Brown Dwarf Populations in Star-Forming Regions

2003 ◽  
Vol 211 ◽  
pp. 87-90
Author(s):  
M. Tamura ◽  
T. Naoi ◽  
Y. Oasa ◽  
Y. Nakajima ◽  
C. Nagashima ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Brown Dwarf ◽  
Ir Camera ◽  
Star Forming ◽  
Star Forming Regions ◽  
New Instrument ◽  
Infrared Surveys ◽  
Low Mass

We are currently conducting three kinds of IR surveys of star forming regions (SFRs) in order to seek for very low-mass young stellar populations. First is a deep JHKs-bands (simultaneous) survey with the SIRIUS camera on the IRSF 1.4m or the UH 2.2m telescopes. Second is a very deep JHKs survey with the CISCO IR camera on the Subaru 8.2m telescope. Third is a high resolution companion search around nearby YSOs with the CIAO adaptive optics coronagraph IR camera on the Subaru. In this contribution, we describe our SIRIUS camera and present preliminary results of the ongoing surveys with this new instrument.

scholarly journals Searching for intergalactic star forming regions in Stephan’s Quintet with SITELLE

2019 ◽  
Vol 629 ◽  
pp. A102 ◽  
Author(s):  
S. Duarte Puertas ◽  
J. Iglesias-Páramo ◽  
J. M. Vilchez ◽  
L. Drissen ◽  
C. Kehrig ◽  
...  
Keyword(s):  
Large Scale ◽  
Dwarf Galaxy ◽  
Three Dimensional ◽  
Large Field ◽  
North West ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
The North ◽  
Spectral Ranges

Stephan’s Quintet (SQ), the prototypical compact group of galaxies in the local Universe, has been observed with the imaging Fourier transform spectrometer SITELLE, attached to the Canada-France-Hawaii-Telescope, to perform a deep search for intergalactic star-forming emission. In this paper we present the extended ionised gaseous structures detected and analyse their kinematical properties. The large field of view (11′ × 11′) and the spectral ranges of SITELLE have allowed a thorough study of the entire galaxy system, its interaction history and the main properties of the ionised gas. The observations have revealed complex three-dimensional strands in SQ seen for the first time, as well as the spatially resolved velocity field for a new SQ dwarf galaxy (M 82-like) and the detailed spectral map of NGC 7320c, confirming its AGN nature. A total of 175 SQ Hα emission regions have been found, 22 of which present line profiles with at least two kinematical components. We studied 12 zones and 28 sub-zones in the SQ system in order to define plausible physical spatial connections between its different parts in the light of the kinematical information gathered. In this respect we have found five velocity systems in SQ: (i) v = [5600−5900] km s−1 associated with the new intruder and the southern debris region; (ii) v = [5900−6100] km s−1, associated with the north starburst A and south starburst A and the strands connected to these zones; (iii) v = [6100−6600] km s−1, associated with the strands from the large-scale shock region (LSSR); (iv) v = [6600−6800] km s−1, associated with the young tidal tail, the starburst A (SQA), NGC 7319, and the NGC 7319 north lobe; and (v) v = [6800−7000] km s−1, associated with the strands seen connecting LSSR with SQA. We fail to detect ionised gas emission in the old tail, neither in the vicinity of NGC 7318A nor in NGC 7317, and the connection between NGC 7319 north lobe and SQA cannot be confirmed. Conversely, a clear gaseous bridge has been confirmed both spatially and kinematically between the LSSR zone and the NGC 7319 AGN nucleus. Finally, a larger scale, outer rim winding the NGC 7318B/A system clockwise north-west to south-east has been highlighted in continuum and in Hα. This structure may be reminiscent of a sequence of a previously proposed scenario for SQ a sequence of individual interactions.

scholarly journals SDSS-IV MaNGA: effects of morphology in the global and local star formation main sequences

2019 ◽  
Vol 488 (3) ◽  
pp. 3929-3948 ◽  
Author(s):  
M Cano-Díaz ◽  
V Ávila-Reese ◽  
S F Sánchez ◽  
H M Hernández-Toledo ◽  
A Rodríguez-Puebla ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Main Sequence ◽  
Formation Rate ◽  
Stellar Mass ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Formation Activity ◽  
Global And Local ◽  
Universal Mechanism

ABSTRACT We study the global star formation rate (SFR) versus stellar mass (M*) correlation, and the spatially resolved SFR surface density (ΣSFR) versus stellar mass surface density (Σ*) correlation, in a sample of ∼2000 galaxies from the MaNGA MPL-5 survey. We classify galaxies and spatially resolved areas into star forming and retired according to their ionization processes. We confirm the existence of a star-forming main sequence (SFMS) for galaxies and spatially resolved areas, and show that they have the same nature, with the global as a consequence of the local one. The latter presents a bend below a limit Σ* value, ≈3 × 107 M$\odot$ kpc−2, which is not physical. Using only star-forming areas (SFAs) above this limit, a slope and a scatter of ≈1 and ≈0.27 dex are determined. The retired galaxies/areas strongly segregate from their respective SFMSs, by ∼−1.5 dex on average. We explore how the global/local SFMSs depend on galaxy morphology, finding that for star-forming galaxies and SFAs, there is a trend to lower values of star formation activity with earlier morphological types, which is more pronounced for the local SFMS. The morphology not only affects the global SFR due to the diminish of SFAs with earlier types, but also affects the local SF process. Our results suggest that the local SF at all radii is established by some universal mechanism partially modulated by morphology. Morphology seems to be connected to the slow aging and sharp decline of the SF process, and on its own it may depend on other properties as the environment.

scholarly journals Investigations of dust heating in M81, M83 and NGC 2403 with Herschel and Spitzer

2011 ◽  
Vol 7 (S284) ◽  
pp. 97-100
Author(s):  
George J. Bendo ◽  
Keyword(s):  
Star Formation ◽  
Flux Density ◽  
Near Infrared ◽  
Dust Emission ◽  
Far Infrared ◽  
Spectral Energy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Star Formation Activity ◽  
Density Ratios

AbstractWe use Herschel Space Observatory and Spitzer Space Telescope 70-500 μm data along with ground-based optical and near-infrared data to understand how dust heating in the nearby face-on spiral galaxies M81, M83, and NGC 2403 is affected by the starlight from all stars and by the radiation from star-forming regions. We find that 70/160 μm flux density ratios tend to be more strongly influenced by star-forming regions. However, the 250/350 and 350/500 μm micron flux density ratios are more strongly affected by the light from the total stellar populations, suggesting that the dust emission at > 250 μm originates predominantly from a component that is colder than the dust seen at <160 μm and that is relatively unaffected by star formation activity. We conclude by discussing the implications of this for modelling the spectral energy distributions of both nearby and more distant galaxies and for using far-infrared dust emission to trace star formation.

scholarly journals Star formation on galactic scales

2006 ◽  
Vol 2 (S237) ◽  
pp. 311-316
Author(s):  
Robert C. Kennicutt
Keyword(s):  
Star Formation ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
Multi Wavelength ◽  
Nearby Galaxies

AbstractNew multi-wavelength data on nearby galaxies are providing a much more accurate and complete observational picture of star formation on galactic scales. Here I briefly report on recent results from the Spitzer Infrared Nearby Galaxies Survey (SINGS). These provide new constraints on the frequency and lifetime of deeply obscured star-forming regions in galaxies, the measurement of dust-corrected star formation rates in galaxies, and the form of the spatially-resolved Schmidt law.

scholarly journals Multiplicity and clustering in Taurus star forming region

2018 ◽  
Vol 620 ◽  
pp. A27 ◽  
Author(s):  
Isabelle Joncour ◽  
Gaspard Duchêne ◽  
Estelle Moraux ◽  
Frédérique Motte
Keyword(s):  
Star Formation ◽  
Nearest Neighbor ◽  
Spatial Clustering ◽  
Mean Value ◽  
K Nearest Neighbor ◽  
Star Forming ◽  
Star Forming Regions ◽  
Wide Pairs ◽  
A Chain ◽  
The One

Context. Multiplicity and clustering of young pre-main sequence stars appear as critical clues to understand and constrain the star formation process. Taurus is the archetypical example of the most quiescent star forming regions that may still retain primeval signatures of star formation. Aims. This work identifies local overdense stellar structures as a critical scale between wide pairs and loose groups in Taurus. Methods. Using the density-based spatial clustering of applications with noise (dbscan) algorithm, and setting its free parameters based on the one-point correlation function and the k-nearest neighbor statistics, we have extracted reliably overdense structures from the sky-projected spatial distribution of stars. Results. Nearly half of the entire stellar population in Taurus is found to be concentrated in 20 very dense, tiny and prolate regions called NESTs (for Nested Elementary STructures). They are regularly spaced (≈2 pc) and mainly oriented along the principal gas filaments axes. Each NEST contains between four and 23 stars. Inside NESTs, the surface density of stars may be as high as 2500 pc−2 and the mean value is 340 pc−2. Nearly half (11) of these NESTs contain about 75% of the class 0 and I objects. The balance between Class I, II, and, III fraction within the NESTs suggests that they may be ordered as an evolutionary temporal scheme, some of them getting infertile with time, while other still giving birth to young stars. We have inferred that only 20% of stars in Taurus do not belong to any kind of stellar groups (either multiple system, ultra wide pairs or NESTs). The mass-size relation for stellar NESTs is very close to the Bonnor–Ebert expectation. The range in mass is about the same as that of dense molecular cores. The distribution in size is bimodal peaking at 12.5 and 50 kAU and the distribution of the number of YSOs in NESTs as a function of size exhibits two regimes. Conclusions. We propose that the NESTs in their two size regimes represent the spatial imprints of stellar distribution at birth as they may have emerged within few millions years from their natal cloud either from a single core or from a chain of cores. We have identified them as the preferred sites of star formation in Taurus. These NESTs are the regions of highest stellar density and intermediate spatial scale structures between ultra-wide pairs and loose groups.

scholarly journals Medium-resolution spectrum of the exoplanet HIP 65426 b

2021 ◽  
Vol 648 ◽  
pp. A59
Author(s):  
S. Petrus ◽  
M. Bonnefoy ◽  
G. Chauvin ◽  
B. Charnay ◽  
G.-D. Marleau ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Adaptive Optics ◽  
Molecular Mapping ◽  
Gravitational Instability ◽  
Atmospheric Models ◽  
Star Forming ◽  
Star Forming Regions ◽  
Medium Resolution ◽  
Core Accretion ◽  
Integral Field

Medium-resolution integral-field spectrographs (IFS) coupled with adaptive-optics such as Keck/OSIRIS, VLT/MUSE, or SINFONI are appearing as a new avenue for enhancing the detection and characterization capabilities of young, gas giant exoplanets at large heliocentric distances (>5 au). We analyzed K-band VLT/SINFONI medium-resolution (Rλ ~5577) observations of the young giant exoplanet HIP 65426 b. Our dedicated IFS data analysis toolkit (TExTRIS) optimized the cube building, star registration, and allowed for the extraction of the planet spectrum. A Bayesian inference with the nested sampling algorithm coupled with the self-consistent forward atmospheric models BT-SETTL15 and Exo-REM using the ForMoSA tool yields Teff = 1560 ± 100 K, log(g) ≤ 4.40 dex, [M/H] = 0.05−0.22+0.24 dex, and an upper limit on the C/O (≤0.55). The object is also re-detected with the so-called “molecular mapping” technique. The technique yields consistent atmospheric parameters, but the loss of the planet pseudo-continuum in the process degrades or modifies the constraints on these parameters. The solar to sub-solar C/O ratio suggests an enrichment by solids at formation if the planet was formed beyond the water snowline (≥20 au) by core accretion (CA hereafter). However, a formation by gravitational instability (GI hereafter) cannot be ruled out. The metallicity is compatible with the bulk enrichment of massive Jovian planets from the Bern planet population models. Finally, we measure a radial velocity of 26 ± 15 km s−1 compatible with our revised measurement on the star. This is the fourth imaged exoplanet for which a radial velocity can be evaluated, illustrating the potential of such observations for assessing the coevolution of imaged systems belonging to star forming regions, such as HIP 65426.

scholarly journals SDSS-IV MaNGA: spatially resolved dust attenuation in spiral galaxies

2020 ◽  
Vol 495 (2) ◽  
pp. 2305-2320
Author(s):  
Michael J Greener ◽  
Alfonso Aragón-Salamanca ◽  
Michael R Merrifield ◽  
Thomas G Peterken ◽  
Amelia Fraser-McKelvie ◽  
...  
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Formation Rate ◽  
Stellar Populations ◽  
High Concentration ◽  
Full Spectrum ◽  
Star Forming ◽  
Spatially Resolved ◽  
Radial Profiles ◽  
Dust Attenuation

ABSTRACT Dust attenuation in star-forming spiral galaxies affects stars and gas in different ways due to local variations in dust geometry. We present spatially resolved measurements of dust attenuation for a sample of 232 such star-forming spiral galaxies, derived from spectra acquired by the SDSS-IV MaNGA survey. The dust attenuation affecting the stellar populations of these galaxies (obtained using full spectrum stellar population fitting methods) is compared with the dust attenuation in the gas (derived from the Balmer decrement). Both of these attenuation measures increase for local regions of galaxies with higher star formation rates; the dust attenuation affecting the stellar populations increases more so than the dust attenuation in the gas, causing the ratio of the dust attenuation affecting the stellar populations to the dust attenuation in the gas to decrease for local regions of galaxies with higher star formation rate densities. No systematic difference is discernible in any of these dust attenuation quantities between the spiral arm and interarm regions of the galaxies. While both the dust attenuation in the gas and the dust attenuation affecting the stellar populations decrease with galactocentric radius, the ratio of the two quantities does not vary with radius. This ratio does, however, decrease systematically as the stellar mass of the galaxy increases. Analysis of the radial profiles of the two dust attenuation measures suggests that there is a disproportionately high concentration of birth clouds (incorporating gas, young stars, and clumpy dust) nearer to the centres of star-forming spiral galaxies.

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